Solas Explainatory

SOLAS Consolidated Edition 2009 with

Explanatory Notes (Res. MSC.281(85)) Applicable to Passenger and Cargo Ships of all Sizes & Dry Cargo Ships with Length => 80 m with keels laid on or after 1st January, 2009 KEY TO COLOUR CODES and FONTS USED IN THIS DOCUMENT SOLAS Consolidated Edition 2009; Resolution MSC.281(85); Regulation 2.9 (ref. SLF 52/17/6 - Norway); Regulation 4.3 (ref. SLF 52/3/3 - Germany) Regulation 4.1 (ref. SLF 52/17/6 - Norway) [Coordinator’s Note:] MSC Circulars Round 1/2 Discussion: Q1A Q1B Agreed Regulatory Text Changes Agreed EN Text Changes Rejected Regulatory Text Changes Rejected EN Text Changes Q1C Q1D Proposed Regulatory Text Changes Proposed EN Text Changes NFA

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Current SOLAS text Current Explanatory Notes (EN) Proposed changes to SOLAS text with ref. Proposed changes to EN (with ref.) Proposed changes to footnotes (with ref.) Guidance and suggested minor changes MSC Circulars referred to in the text Co-ordinator’s comments on Round 1/2 Round 2 questions Round 3 questions for discussion at SLF53 Changes to SOLAS agreed in SLF53/WP.6 Changes to EN text agreed in SLF 53/WP.6 Changes to SOLAS rejected at SLF 53 Changes to EN text rejected at SLF 53 Round 4 questions for 2011 CG Questions for discussion at SLF53 Changes to SOLAS proposed by 2011 CG Changes to EN text proposed by 2011 CG No Further Action – leave text unchanged

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UPDATES TO SOLAS 2009 AMENDMENTS To simplify the task of discussing and agreeing updates to the SOLAS regulations, this document includes the full text of the SOLAS Consolidated Edition 2009 in black Ariel 11 font and the explanatory notes from Resolution MSC.281(85) in red Ariel 11 italic font. Any MSC Circulars referred to in the regulations or explanatory notes are also included in black Times New Roman 11 font. Most of the text is in Word though some sections containing complex formulae and figures use Adobe .pdf and cannot be edited. Changes to be discussed by this CG, including suggestions for possible amendments to SOLAS 2009, are shown in blue and are taken largely from SLF 51/3/2 to 51/3/7 and 52/17/1 to 52/17/6 (see Table 1 below). Proposed amendments to the explanatory notes taken from the above papers are highlighted in green and proposed amendments to the footnotes are highlighted in turquoise (see in particular SLF 52/WP.5, Agenda Item 14). Each proposed change to the regulations, EN or footnotes is inserted into the text at the relevant point with a space for questions and comments. Some minor suggestions for changing the text are highlighted in yellow for consideration by the CG (see Regs 13.11.1, 15.4, 15.5.1 & 35-1.2.3, for example). Changes needed to the 2009 Consolidated text already agreed in MSC.269(85) are similarly highlighted.

Ref. SLF 51/3/2

Date

By

Subject

10/04/08

Sweden+US

SDS CG report for possible future For this improvements to SOLAS Ch II-1 CG to consider regulations; includes the following Reg 1 - Application; para 1.3.4 Reg 5-1 - Information to the master para. 3 para. 4 Reg 7 - Index A; para 2 para. 6 Reg 7-1 - Calculation of factor pi; para 1 para. 1.2 Reg 7-2 - Calculation of factor si; para 2 para. 4 para. 4.1.1 paras 5.2 and 5.3 Reg 8 - Clarify N formula; paras 3.2-3.5 Reg 9 - Double bottoms; para. 8 Reg 12 - s = 1 fwd of collision bhd proposed new para. Reg17 - WT integrity above bhd dk para. 3 Reg 22 - Clarify heading Reg 24 - Clarify heading Reg 35-1 - Mods may be needed

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Ref.

Date

By

Subject

Status

SLF 51/3/3

29/04/08 Germany

Status of the Explanatory Notes Not confirmed. (proposal to make some mandatory) Germany reserves position.

SLF 51/3/4

09/05/08 IACS

Reg 12.5.1 Requirements for pipes For this CG to piercing collision bulkheads consider

SLF 51/3/5 SLF 51/3/6

09/05/08 IACS

Reg 9.3 - Interpretation of DB height

(Ref. 51/17/3.21)

(Ref.51/17/Annex 3)

SLF 51/3/7 SLF 51/17 SLF 52/17/1 SLF 52/17/2 SLF 52/17/3 SLF 52/17/4

SLF 52/17/5

SLF 52/17/6

Not accepted (Ref. 51/WP.1para 6)

22/05/08 China

Reg 5-1/3 and /4 - Proposed mods to EN for trim range and critical KG/GM curves 23/05/08 Norway Reg 13.4; main or aux mchy separated by longitudinal bhd 28/08/08 Secretariat Report from SLF 51 to MSC85 covering Agenda Item 3; see paras 3.1 – 3.22 26/10/09 Germany Reg 7-2 - Uniform application of crossflooding provisions 26/10/09 Germany

Reg 19 - Damage control information

19/11/09 Finland

Reg 7-1 - Enhancement to EN

20/11/09 Norway

Proposes amendments to the following Reg 5-1 - Information to Master Reg 7 - Index A; mod 7.1 .2 & add 7.3 Reg 4 - footnote Regs 5-1.3, 5-1.4 and 7.2 EN Regs 7.1 and 7.2 EN These are comments on SLF 51/3/2:Reg 1 - Application; para 1.3.4 Reg 7 - Index A, 1 free surface; para 6 Reg 7-1 - Calc of factor pi; paras 1 &1.2 Reg 7-2 - Calc of factor si; para 4 Reg 8 - Keep text for N; para 3.2 to .5 Reg 35-1 - Clarify L & N; paras 3.2 .4 .9 Further proposed amendments to:Reg 2 - Definitions in paras 9 and 13 Reg 4 - General; para 1 Reg 5 - Intact Stability; para 1 Reg 5-1- Stability info to master; para 4 Reg 7-2 - Calculation of factor si; para 2 Reg 8 - Consistent use of L; factor si Reg 12 - New para for si = 1; collsn bhd Reg 17 - WT integrity; para 3 and EN Reg 20 - should not be limited to pax ships; para 1 – add “ship to be upright etc”; propose to add heel tolerance.

Accepted EN already amended

Accepted EN amended

For this CG to consider “ “

20/11/09 Norway

20/11/09 Norway

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“

“

“

Ref.

Date

By

Subject

Status

MSC 85/23/1

18/06/08 UK

Reg 4 - proposal to delete footnote .4 For this and update references to remaining CG to footnotes such as .6 & .7 as necessary consider

SLF 52/ WP.5/ 14.2 Res. MSC. 269(85)

29/1/10

Reg 4 – Germany requests footnotes .6 and .7 to be considered for deletion

Adopted 4/12/08

Rpt of June ‘10 CSSF WG v04

S-C MSC

Part A reg 2 ; new para 27 Part B-1 reg 5; change to heading ; new sentence in para 1

CLIA/CSSF* Reg 4 – MARPOL to be excluded from Part B-1 damage

“ Not in 2009 Consolidated Ed. Highlighted in yellow in this doc For this CG to Consider in R2

Reg. 7-2.5.3, delete “at each boundary” Reg. 2.11; additional text Reg. 5-1.3/4 EN2; text changes Reg. 7.2; mods to 52/17/4 proposals Reg. 7.5; change to centreline text Reg. 7.7; EN 1 extra text – valve size Reg. 7.7; EN2 clarification – pipe area Reg. 7-1; addition to 52/17/3 – diagram Reg. 7-1.1.2 EN 12 – as for 7.7 EN1 Reg. 7-2.2 EN 1-4; various mods. Reg. 7-2.5.2.2 EN 1,2&5; horiz Esc R Reg. 9.2; additional text + diagram Reg 17.1; remove “sliding”

“

“

“

Table 1 Papers containing proposed changes to SOLAS 2009 regulations, footnotes and Explanatory Notes * The working group of the CSSF has identified a number of smaller corrections and additions to SOLAS2009 II-1 and the corresponding explanatory notes. Only those proposals are presented in this paper which have supported by a clear majority of the working group members. In addition some topics have been identified, where no consensus could be reached, but which are worth to be further discussed in the ISCG and at the SDS working group during SLF53.

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SOLAS Regulations as amended on 1/1/2009 This document contains the amendments to the old SOLAS Chapter II-1 Parts A, B and B-1 which have been completely replaced by the following regulations now incorporated into the SOLAS Consolidated Edition 2009. Regulations shown in red have EN.

CONTENTS Part A - General Regulation 1 ...................................................................................................Application Regulation 2 ....................................................................................................Definitions Regulation 3 ........................................................Definitions Relating to parts C, D and E Part B - Subdivision and stability Regulation

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....................................................................................................General

Part B-1 - Stability Regulation 5 .............................................................................Intact stability information Regulation 5-1 .....................................Stability information to be supplied to the master Regulation 6 ..........................................................................Required subdivision index R Regulation 7 …......................................................................Attained subdivision index A Regulation 7-1 ............................................................................Calculation of the factor pi Regulation 7-2 ............................................................................Calculation of the factor si Regulation 7-3 …..............................................................................................Permeability Regulation 8 ...............................Special requirements concerning passenger ship stability Regulation 8-1 ..............................System capabilities and operational information after a flooding casualty on passenger ships Part B-2 - Subdivision, watertight and weathertight Integrity Regulation 9 ....Double bottoms in passenger ships and cargo ships other than tankers Regulation 10 ...........................................................Construction of watertight bulkheads Regulation 11 …...............................................Initial testing of watertight bulkheads etc Regulation 12 …...........................Peak and machinery space bulkheads, shaft tunnels, etc Regulation 13 …………..Openings in watertight bulkheads below the bulkhead deck in passenger ships Regulation 13-1..........Openings in watertight bulkheads and internal decks in cargo ships Regulation 14 ........Passenger ships carrying goods vehicles and accompanying personnel Regulation 15 .........Openings in the shell plating below the bulkhead deck of passengers ships and the freeboard deck of cargo ships Regulation 15-1 ............................................................External openings in cargo ships Regulation 16 ...............Construction and initial tests of watertight doors, sidescuttles etc Regulation 16-1 ....................Construction and initial tests of watertight decks, trunks etc Regulation 17 ....Internal watertight integrity of passenger ships above the bulkhead deck Regulation 17-1 …………Integrity of the hull and superstructure, damage prevention and control on ro-ro passenger ships

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Part B-3 - Subdivision load line assignment for passenger ships Regulation 18 ....Assigning, marking and recording of subdivision load lines for passenger ships Part B-4 - Stability management Regulation 19 .........................................................................Damage Control Information Regulation 20 ...................... ..................................................Loading of [passenger] Ships [See Q53 – proposal to delete “Passenger” rejected by WG at SLF 53. But now see Q53D] Regulation 21 ....................Periodical operation and inspection of watertight doors, etc., in passenger ships Regulation 22 ..............Prevention and control of water ingress, etc. [in passenger ships and cargo ships] – [Clarification proposed in SLF 51/3/2, rejected by SLF 53 WG. NFA]

Regulation 22-1 ......Flooding detection systems for passenger ships carrying 36 or more persons constructed on or after 1/7/2010 Regulation 23 ..............................................Special requirements for ro-ro passenger ships Regulation 24 ...............................[ Additional measures for the] [Additional requirements for] prevention and control of water ingress, etc., in cargo ships [only] – [Ref. SLF 51/3/2, also see Reg. 22; “Additional measures etc… agreed by SLF 53 WG but “only” rejected; new US proposal in blue for approval at SLF 54] [see Q58D]

Regulation 25 ………......Water level detectors on single hold cargo ships other than bulk carriers Part C – Machinery installations Regulation 35-1 .....................................................................Bilge Pumping Arrangements Associated MSC Resolutions included in the text below for easy reference Adoption of Amendments to the International Convention for the Safety of Life at Sea, 1974, as amended (Ref. Resolution MSC.216(82), adopted on 8th October, 2006) Recommendation on a Standard Method for Evaluating Cross-Flooding Arrangements (Ref. Resolution MSC.245(83), adopted on 12th October, 2007) Adoption of Amendments to the International Convention for the Safety of Life at Sea, 1974, as amended (Ref. Resolution MSC.269(85), adopted on 4th December, 2008) [Amendments not included in SOLAS Consolidated Edition 2009 but highlighted thus in this document]

Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations (Ref. Resolution MSC.281(85), adopted on 4th December, 2008)

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Associated MSC Circulars included in the text below for easy reference Guidance Notes on the Integrity of Flooding Boundaries above the Bulkhead Deck of Passenger Ships (Ref. MSC/Circ.541, dated 19th July, 1990) Unified Interpretation regarding Timber Deck Cargo in the Context of Damage Stability Requirements (Ref. MSC/Circ.998, dated 25th July, 2001) Unified Interpretations to SOLAS II-1 Part B-1 Regulation 5 regarding Stability Information for Passenger and Cargo Ships (Lightweight Check) (Ref. MSC/Circ.1158, dated 24th May, 2005) Unified Interpretations to SOLAS Chapter II-1 Regulation12 regarding Bow Doors and the Extension of the Collision Bulkhead. (Ref. MSC.1/Circ.1211, dated 25th May, 2006) Performance Standards for the Systems and Services to Remain Operational on Passenger Ships for Safe Return to Port and Orderly Evacuation and Abandonment after a Casualty (Ref. MSC.1/Circ.1214, dated 15th December, 2006) Guidelines for Damage Control Plans and Information to the Master. (Ref. MSC.1/Circ.1245, dated 29th October, 2007) Interpretation of Alterations and Modifications of a Major Character (Ref. MSC.1/Circ.1246, dated 29th October, 2007, which supersedes MSC/Circ.650). Guidelines for Flooding Detection Systems on Passenger Ships. (Ref. MSC.1/Circ.1291, adopted on 9th December, 2008) Guidelines for the Drainage of Fire-Fighting Water from Closed Vehicle and Ro-Ro Spaces and Special Category Spaces of Passenger and Cargo Ships. (Ref. MSC.1/Circ.1320, dated 11th June, 2009) Guidance for watertight doors on passenger ships which may be opened during navigation. (Ref. MSC.1/Circ.1380, dated 10th December, 2010)

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RESOLUTION MSC.281(85) (adopted on 4 December 2008) EXPLANATORY NOTES TO THE SOLAS CHAPER II-1 SUBDIVISION AND DAMAGE STABILITY REGULATIONS THE MARITIME SAFETY COMMITTEE, RECALLING Article 28(b) of the Convention on the International Maritime Organization concerning the function of the Committee, RECALLING ALSO that, by resolution MSC.216(82), it adopted the regulations on subdivision and damage stability as contained in SOLAS chapter II-1 which are based on the probabilistic concept, using the probability if survival after collision as a measure of ships’ safety in a damage condition, NOTING that, at the eighty-second session, it approved Interim Explanatory Notes to the SOLAS chapter II-1 subdivision and damage stability regulations (MSC.1/Circ.1226), to assist Administrations in the uniform interpretation and application of the aforementioned subdivision and damage stability regulations. BEING DESIROUS that definitive Explanatory Notes should be adopted when more experience in the application of the aforementioned subdivision and damage stability regulations and the Interim Explanatory Notes had been gained, RECOGNIZING that the appropriate application of the Explanatory Notes is essential for ensuring the uniform application of the SOLAS chapter II-1 subdivision and damage stabilioty regulations, HAVING CONSIDERED, at its eighty-fifth session, the recommendations made by the Sub-Committee on Stability and Load Lines and on Fishing Vessels Safety at its fifty-first session, 1. ADOPTS the Explanatory Notes to the SOLAS chapter II-1 subdivision and damage stability regulations set out in the Annex to the present resolution; 2. URGES Governments and all parties concerned to utilize the Explanatory Notes when applying the SOLAS chapter II-1 subdivision and damage stability regulations adopted by resolution MSC.216(82).

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EXPLANATORY NOTES TO THE SOLAS CHAPTER II-1 SUBDIVISION AND DAMAGE STABILITY REGULATIONS

Contents

Part A - INTRODUCTION Part B - GUIDANCE ON INDIVIDUAL SOLAS CHAPTER II-1 SUBDIVISION AND DAMAGE STABILITY REGULATIONS Regulation 1 Regulation 2 Regulation 4 Regulation 5 Regulation 5-1 Regulation 6 Regulation 7 Regulation 7-1 Regulation 7-2 Regulation 7-3 Regulation 8 Regulation 8-1 Regulation 9 Regulation 10 Regulation 12 Regulation 13 Regulation 13-1 Regulation 15 Regulation 15-1 Regulation 16 Regulation 17 Appendix

Application Definitions General Intact stability information Stability information to be supplied to the master Required subdivision index R Attained subdivision index A Calculation of the factor pi Calculation of the factor si Permeability Special requirements concerning passenger ship stability System capabilities and operational information after a flooding casualty on passenger ships Double bottoms in passenger ships and cargo ships other than tankers Construction of watertight bulkheads Peak and machinery space bulkheads, shaft tunnels, etc. Openings in watertight bulkheads below the bulkhead deck in passenger ships Openings in watertight bulkheads and internal decks in cargo ships Openings in the shell plating below the bulkhead deck of passenger ships and the free board deck of cargo ships External openings in cargo ships Construction and initial tests of watertight doors, sidescuttles, etc. Internal watertight integrity of passenger ships above the bulkhead deck Guidelines for the preparation of subdivision and damage stability calculations

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PART A INTRODUCTION 1 The harmonized SOLAS regulations on subdivision and damage stability, as contained in revised SOLAS chapter II-1 are based on a probabilistic concept which uses the probability of survival after collision as a measure of ships’ safety in a damaged condition. This probability is referred to as the “attained subdivision index A” in the regulations. This can be considered an objective measure of ship safety and, ideally, there would be no need to supplement this index by any deterministic requirements. 2 The philosophy behind the probabilistic concept is that two different ships with the same attained index are of equal safety and, therefore, there is no need for special treatment of specific parts of the ship, even if they are able to survive different damages. The only areas which are given special attention in these regulations are the forward and bottom regions which are dealt with by special subdivision rules provided for the cases of ramming and grounding. 3 Only a few deterministic elements, which were necessary to make the concept practicable, have been included. It was also necessary to include a deterministic “minor damage” on top of the probabilistic regulations for passenger ships to avoid ships being designed with what might be perceived as unacceptably vulnerable spots in some part of their length. 4 It is easily recognized that there are many factors that will affect the final consequences of hull damage to the ship. These factors are random and their influence is different for ships with different characteristics. For example, it would seem obvious that in ships of similar size carrying different amounts of cargo, damages of similar extents may lead to different results because of differences in the range of permeability and draught during service. The mass and velocity of the ramming ship is obviously another random variable. 5 Due to this, the effect of a three-dimensional damage to a ship with given watertight subdivision depends on the following circumstances: .1

which particular space or group of adjacent spaces is flooded;

.2

the draught, trim and intact metacentric height at the time of damage;

.3

the permeability of affected spaces at the time of damage;

.4

the sea state at the time of damage; and

.5

other factors, such as possible heeling moments due to unsymmetrical weights.

6 Some of these circumstances are interdependent and the relationship between them and their effects may vary in different cases. Additionally, the effect of hull strength on penetration will obviously have some effect on the results for a given ship. Since the location and size of the damage is random, it is not possible to state which part of the

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ship becomes flooded. However, the probability of flooding a given space can be determined if the probability of occurrence of certain damages is known from experience, that is, damage statistics. The probability of flooding a space is then equal to the probability of occurrence of all such damages which just open the considered space to the sea. 7 For these reasons and because of mathematical complexity as well as insufficient data, it would not be practicable to make an exact or direct assessment of their effect on the probability that a particular ship will survive a random damage if it occurs. However, accepting some approximations or qualitative judgments, a logical treatment may be achieved by using the probability approach as the basis of a comparative method for the assessment and regulation of ship safety. 8 It may be demonstrated by means of probability theory that the probability of ship survival should be calculated as a sum of probabilities of its survival after flooding each single compartment, each group of two, three, etc., adjacent compartments multiplied, respectively, by the probabilities of occurrence of such damages as lead to the flooding of the corresponding compartment or group of compartments. 9 If the probability of occurrence for each of the damage scenarios the ship could be subjected to is calculated and then combined with the probability of surviving each of these damages with the ship loaded in the most probable loading conditions, we can determine the attained index A as a measure for the ship’s ability to sustain a collision damage. 10 It follows that the probability that a ship will remain afloat without sinking or capsizing as a result of an arbitrary collision in a given longitudinal position can be broken down to: .1

the probability that the longitudinal centre of damage occurs in just the region of the ship under consideration;

.2

the probability that this damage has a longitudinal extent that only includes spaces between the transverse watertight bulkheads found in this region;

.3

the probability that the damage has a vertical extent that will flood only the spaces below a given horizontal boundary, such as a watertight deck;

.4

the probability that the damage has a transverse penetration not greater than the distance to a given longitudinal boundary; and

.5

the probability that the watertight integrity and the stability throughout the flooding sequence is sufficient to avoid capsizing or sinking.

11 The first three of these factors are solely dependent on the watertight arrangement of the ship, while the last two depend on the ship’s shape. The last factor also depends on the actual loading condition. By grouping these probabilities, calculation of the probability of survival, or attained index A, have been formulated to include the following probabilities: .1

the probability of flooding each single compartment and each possible group of two or more adjacent compartments; and

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.2

the probability that the stability after flooding a compartment or a group of two or more adjacent compartments will be sufficient to prevent capsizing or dangerous heeling due to loss of stability or to heeling moments in intermediate or final stages of flooding.

12 This concept allows a rule requirement to be applied by requiring a minimum value of A for a particular ship. This minimum value is referred to as the “required subdivision index R” in the present regulations and can be made dependent on ship size, number of passengers or other factors legislators might consider important. 13

Evidence of compliance with the rules then simply becomes:

A≥R As explained above, the attained subdivision index A is determined by a formula for the entire probability as the sum of the products for each compartment or group of compartments of the probability that a space is flooded, multiplied by the probability that the ship will not capsize or sink due to flooding of the considered space. In other words, the general formula for the attained index can be given in the form: A = Σpi.si Subscript “i” represents the damage zone (group of compartments) under consideration within the watertight subdivision of the ship. The subdivision is viewed in the longitudinal direction, starting with the aftmost zone/compartment. The value of “pi” represents the probability that only the zone “i” under consideration will be flooded, disregarding any horizontal subdivision, but taking transverse subdivision into account. Longitudinal subdivision within the zone will result in additional flooding scenarios, each with their own probability of occurrence. The value of “si” represents the probability of survival after flooding the zone “i” under consideration. 14 Although the ideas outlined above are very simple, their practical application in an exact manner would give rise to several difficulties if a mathematically perfect method was to be developed. As pointed out above, an extensive but still incomplete description of the damage will include its longitudinal and vertical location as well as its longitudinal, vertical and transverse extent. Apart from the difficulties in handling such a fivedimensional random variable, it is impossible to determine its probability distribution very accurately with the presently available damage statistics. Similar limitations are true for the variables and physical relationships involved in the calculation of the probability that a ship will not capsize or sink during intermediate stages or in the final stage of flooding. 15 A close approximation of the available statistics would result in extremely numerous and complicated computations. In order to make the concept practicable, extensive simplifications are necessary. Although it is not possible to calculate the exact probability of survival on such a simplified basis, it has still been possible to develop a useful comparative measure of the merits of the longitudinal, transverse and horizontal subdivision of the ship.

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RESOLUTION MSC.216(82) (adopted on 8 December 2006) ADOPTION OF AMENDMENTS TO THE INTERNATIONAL CONVENTION FOR THE SAFETY OF LIFE AT SEA, 1974, AS AMENDED

THE MARITIME SAFETY COMMITTEE, RECALLING Article 28(b) of the Convention on the International Maritime Organization concerning the functions of the Committee, RECALLING FURTHER article VIII(b) of the International Convention for the Safety of Life at Sea (SOLAS), 1974 (hereinafter referred to as “the Convention”), concerning the amendment procedure applicable to the Annex to the Convention, other than to the provisions of chapter I thereof, HAVING CONSIDERED, at its eighty-second session, amendments to the Convention, proposed and circulated in accordance with article VIII(b)(i) thereof, 1. ADOPTS, in accordance with article VIII(b)(iv) of the Convention, amendments to the Convention, the text of which is set out in Annexes 1, 2 and 3 to the present resolution; 2. that:

DETERMINES, in accordance with article VIII(b)(vi)(2)(bb) of the Convention, (a)

the said amendments, set out in Annex 1, shall be deemed to have been accepted on 1 January 2008;

(b)

the said amendments, set out in Annex 2, shall be deemed to have been accepted on 1 July 2008; and

(c)

the said amendments, set out in Annex 3, shall be deemed to have been accepted on 1 January 2010,

unless, prior to those dates, more than one third of the Contracting Governments to the Convention or Contracting Governments the combined merchant fleets of which constitute not less than 50% of the gross tonnage of the world’s merchant fleet, have notified their objections to the amendments;

3. INVITES SOLAS Contracting Governments to note that, in accordance with article VIII(b)(vii)(2) of the Convention: (a)

the amendments, set out in Annex 1, shall enter into force on 1 July 2008;

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(b)

the amendments, set out in Annex 2, shall enter into force on 1 January 2009; and

(c)

the amendments, set out in Annex 3, shall enter into force on 1 July 2010, upon their acceptance in accordance with paragraph 2 above;

4. REQUESTS the Secretary-General, in conformity with article VIII(b)(v) of the Convention, to transmit certified copies of the present resolution and the text of the amendments contained in Annexes 1, 2 and 3 to all Contracting Governments to the Convention; 5. FURTHER REQUESTS the Secretary-General to transmit copies of this resolution and its Annexes 1, 2 and 3 to Members of the Organization, which are not Contracting Governments to the Convention.

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ANNEX 2 AMENDMENTS TO THE INTERNATIONAL CONVENTION FOR THE SAFETY OF LIFE AT SEA, 1974, AS AMENDED

CHAPTER II-1 CONSTRUCTION -STRUCTURE, SUBDIVISION AND STABILITY, MACHINERY AND ELECTRICAL INSTALLATIONS The existing text of parts A, B and B-1 of the chapter is replaced by the following:

(Extracts from SOLAS Consolidated Edition 2009)

Part A General Regulation 1 Application 1.1 Unless expressly provided otherwise, this chapter shall apply to ships the keels of which are laid or which are at a similar stage of construction on or after 1 January 2009. 1.2

1.3

For the purpose of this chapter, the term a similar stage of construction means the stage at which: .1

construction identifiable with a specific ship begins; and

.2

assembly of that ship has commenced comprising at least 50 tonnes or one per cent of the estimated mass of all structural material, whichever is less.

For the purpose of this chapter: .1

the expression ships constructed means ships the keels of which are laid or which are at a similar stage of construction;

.2

the expression all ships means ships constructed before, on or after 1 January 2009;

.3

a cargo ship, whenever built, which is converted to a passenger ship shall be treated as a passenger ship constructed on the date on which such a conversion commences;

.4

the expression alterations and modifications of a major character means, in the context of cargo ship subdivision and stability, any modification to the construction which affects the level of subdivision of that ship. Where a cargo ship is subject to such modification, it shall be demonstrated that the A/R ratio calculated for the ship after such modifications is not less than the A/R ratio calculated for the ship before the modification.

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However, in those cases where the ship’s A/R ratio before modification is equal to or greater than unity, it is only necessary that the ship after modification has an A value which is not less than R, calculated for the modified ship. [Q1] Regulation 1.1.3.4 (ref. SLF 51/3/2 – US and Sweden) This provision, regarding cargo ship subdivision and damage stability in the context of alterations and modifications of a major character, is not currently in line with the principles recently agreed to at SLF 50 and approved at MSC 83 in new MSC.1/Circ.1246 (which superseded MSC/Circ.650). This provision should be revised to reflect the principles in MSC.1/Circ.1246 (see SLF 50/19, paragraph 3.17.2) [Coordinator’s Note: MSC.1/Circ.1246 is included below for easy reference]. Regulation 1.1.3.4 (ref. SLF 52/17/5 - Norway) Document SLF 51/3/2 contains a proposal that the paragraph should be revised to reflect the principles in MSC.1/Circ.1246. This Administration agrees that a revision is appropriate. The intended application of paragraph 1.3.4 appears to be unclear. Any ship constructed from 1 January 2009 onwards must comply fully with the revised chapter according to its type and length at all times, not just an A/R evaluation. All older ships are still subject to compliance with regulations 1.3.1 in the previous version of chapter II-1 (and MSC.1/Circ.1246 if adopted by the Administration). In this chapter the expression “major character” is only used for a very limited purpose in paragraph 3. Paragraph 2 on new regulation 1 lists applicable standards for ships constructed before 1 January 2009. Since the damage stability requirements in resolutions MSC.19(58) and MSC.47(66) are included in that list, it would seem inappropriate to apply the provisions of the new chapter in cases where an existing ship continues to comply fully with those provisions after a conversion. For the time being it seems that the only contingency needed in paragraph 1.3.4 with respect to stability is where a dry cargo ship of less than 80 m in length (L) is lengthened beyond that limit. It is proposed that the application of MSC.1/Circ.1246 is limited to ships constructed before 1 January 2009 and that a separate circular be developed to cover ships constructed from 1 January 2009 onwards. It is also proposed that a footnote with reference to MSC.1/Circ.1246 be added to paragraph 3 to cover existing ships. R1.3.4 Alterations and modifications of a major character R1.3 Q1.

Norway suggests that Regulation 1.3.4 is currently unclear in its application; the only situation it needs to cover is when a S2009 cargo ship is lengthened beyond 80 m(L). Norway proposes that a new MSC Circular is needed for ships constructed after 1/1/2009 and that MSC.1/Circ.1246 should only apply to existing ships built before 1/1/2009. A footnote should be added to Regulation 1.3 stating that for ships constructed before 1/1/2009 MSC.1/Circ.1246 should be applied. Do you agree with these proposals?

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Yes

China, Finland, Germany, Japan, MI, Norway, Italy, Spain, Denmark, UK, US, Sweden

No Comments / Alternative Proposals / Suggested wording for footnote?:US: We fully agree with the principles associated with Norway’s proposals. However, we think it would be better to delete regulation 1.1.3.4 completely. This is because for cargo ships built on or after 1 January 2009 there should not be an A/R standard applied (i.e. “Any ship constructed from 1 January 2009 onwards must comply fully with the revised chapter according to its type and length at all times, not just an A/R evaluation.”). This reflects the same principle applied in MSC.1/Circ.1246 (i.e. if constructed on or after 1 July 1998 the ship is never considered an ‘existing cargo ship’). If regulation 1.1.3.4 is deleted, the existing EN for regulation 1.3 (now only addressing passenger ships) could be expanded to indicate: • Application of MSC.1/Circ.1246 is limited to cargo ships constructed before 1 January 2009. • a cargo ship constructed on or after 1 January 2009 of less than 80 m in length that is later lengthened beyond that limit must fully comply with the damage stability regulations according to its type and length. Note: this should also eliminate the need for a footnote regarding MSC.1/Circ.1246. Round 1 Discussion: Although there is strong support for Norway’s proposal it would seem that the US’ suggestions may provide the best solution. Q1A. Recognising that Reg. 1.1.3.4 may be misleading do you support the US proposal to delete it altogether and change EN 1.3 as highlighted below?:Regulation 1.3 .1 If a passenger ship built before 1 January 2009 undergoes alterations or modifications of major character, it may still remain under the damage stability regulations applicable to ships built before 1 January 2009, except in the case of a cargo ship being converted to a passenger ship. .2 Application of MSC.1/Circ.1246 is limited to cargo ships constructed before 1 January 2009 .3 A cargo ship constructed on or after 1 January 2009 of less than 80 m in length that is later lengthened beyond that limit must fully comply with the damage stability regulations according to its type and length. Yes No

MI, Germany, China, Finland, US, Italy, Japan, RINA (see comment 1), France (with comment), Norway, CLIA, UK, Denmark RINA (see comment 2), Sweden

Comments / Alternative Proposals?:MI: Agree deletion of Reg. 1.1.3.4 and change EN 1.3 as proposed by the US. RINA: 1. We would support the deletion of 1.1.3.4 as the definitions to alteration and modifications of a major character for cargo and passenger ships are included in regulation 1.3. 2. With regard to the proposal to amend EN 1.3 we would comment as follows: • 1.3.1 The inclusion of this text conflicts with that in Regulation 1.3. The A/R ratio calculated for the ship after modifications is not less than the A/R ratio calculated for the ship before the modification, is in general, applicable to ships which have their

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damage stability assessed in accordance with a deterministic method. It would then follow that all such ships, when modified, should meet the requirements of MSC.1/Circ.1246. • 1.3.2 If the rationale in 1.3.1 is accepted then MSC.1/Circ.1246 will need to be revised to address alteration and modifications of a major character for passenger and cargo ships which have been assessed against deterministic damage stability calculations. France: US proposal is in line with present explanatory notes. Round 2 Discussion: Although there is a large majority in support of the US proposal to delete regulation 1.1.3.4 and expand EN 1.3, Sweden is opposed and RINA has doubts about the amendments to the EN. Regarding RINA’s comments - our understanding of MSC.1/Circ.1246 is that it was written to cover the situation where a cargo ship built before damage stability regulations were introduced into SOLAS90 Part B-1 on 1st February, 1992 underwent major alterations. Prior to that date cargo ships were not required to comply with any damage stability standards (except ILLC, Reg. 27) so we cannot agree with the RINA statement that such ships would necessarily have had their damage stability assessed against a deterministic standard. For this reason Circ.1246 is specifically addressing cargo ships only and requires new calculations of A/R to be carried out “before and after” major modification to ensure that whatever safety level the vessel had beforehand was either not reduced (if A was R). We therefore believe that the proposed amendments to the EN do make sense as written. Q1B (for SLF53 WG). Can we accept the US proposal to delete Part A Reg. 1.1.3.4 and amend EN 1.3 as shown under Q1A (above)? Yes Proposal accepted by SLF53 WG No Are there any further comments?:- No further discussion in 2011 CG. Q1. Recommend acceptance at SLF54

Ref. T1/2.04

MSC.1/Circ.1246 29 October 2007

INTERPRETATION OF ALTERATIONS AND MODIFICATIONS OF A MAJOR CHARACTER 1. The Maritime Safety Committee, at its sixty-third session (16-25 May 1994), noted that the Sub-Committee on Stability and Load Lines and on Fishing Vessels Safety (SLF), in considering a definition of the term “modification of a major character” in the context of Chapter II-1 of the 1974 SOLAS Convention, had decided that it should be sufficient to relate the modification, whatever its nature and extent, to its effect on the level of subdivision of the ship. The Committee, therefore, agreed to the following interpretation of alterations and modifications of a major character proposed by the SLF Sub-Committee:

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.

“Where an existing cargo ship is subject to any modification which affects the level of subdivision of that ship, it should be demonstrated that the A/R ratio calculated for the ship after such modifications is not less than the A/R ratio calculated for the ship before the modification. However, in those cases where the ship’s A/R ratio before modification is equal to or greater than unity, it is only necessary to demonstrate that the ship after such modification has an ’A’ value which is not less than ’R’, calculated for the modified ship.”

2. The Maritime Safety Committee, at its eighty-third session (3-12 October 2007), considered a definition of the term “existing cargo ship” in the context of the above interpretation and, following a proposal by the SLF Sub-Committee at its fiftieth session, agreed that, in the context of this circular, an existing cargo ship means: .1.

a cargo ship constructed before 1 February 1992, regardless of length; and

.2.

a cargo ship constructed before 1 July 1998, below or equal to 100 m in length.

3. Notwithstanding the above, a cargo ship should not be considered an existing cargo ship if it was: .1

constructed between 1 February 1992 and 30 June 1998, and lengthened from below to above 100 m; and

.2

constructed on or after 1 July 1998.

4. Member Governments are invited to take account of the above interpretation when applying the relevant provisions of Chapter II-1 of the 1974 SOLAS Convention. 5.

This circular supersedes MSC/Circ.650

2 Unless expressly provided otherwise, for ships constructed before 1 January 2009, the Administration shall ensure that the requirements which are applicable under chapter II-1 of the International Convention for the Safety of Life at Sea, 1974, as amended by resolutions MSC.1(XLV), MSC.6(48), MSC.11(55), MSC.12(56), MSC.13(57), MSC.19(58), MSC.26(60), MSC.27(61), Resolution 1 of the 1995 SOLAS Conference, MSC.47(66), MSC.57(67), MSC.65(68), MSC.69(69), MSC.99(73), MSC.134(76), MSC.151(78) and MSC.170(79) are complied with. 3 All ships which undergo repairs, alterations, modifications and outfitting related thereto shall continue to comply with at least the requirements previously applicable to these ships. Such ships, if constructed before the date on which any relevant amendments enter into force, shall, as a rule, comply with the requirements for ships constructed on or after that date to at least the same extent as they did before undergoing such repairs, alterations, modifications or outfitting. Repairs, alterations and modifications of a major character and outfitting related thereto shall meet the requirements for ships constructed on or after the date on which any relevant amendments enter into force, in so far as the Administration deems reasonable and practicable. Regulation 1.3 .1

If a passenger ship built before 1 January 2009 undergoes alterations or

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modifications of major character, it may still remain under the damage stability regulations applicable to ships built before 1 January 2009, except in the case of a cargo ship being converted to a passenger ship. .2 Application of MSC.1/Circ.1246 is limited to cargo ships constructed before 1 January 2009 .3 A cargo ship constructed on or after 1 January 2009 of less than 80 m in length that is later lengthened beyond that limit must fully comply with the damage stability regulations according to its type and length . [Co-ordinator’s Note: See Q1B for a proposal to modify this EN, which was accepted by the WG at SLF 53] 4 The Administration of a State may, if it considers that the sheltered nature and conditions of the voyage are such as to render the application of any specific requirements of this chapter unreasonable or unnecessary, exempt from those requirements individual ships or classes of ships entitled to fly the flag of that State which, in the course of their voyage, do not proceed more than 20 miles from the nearest land. 5 In the case of passenger ships which are employed in special trades for the carriage of large numbers of special trade passengers, such as the pilgrim trade, the Administration of the State whose flag such ships are entitled to fly, if satisfied that it is impracticable to enforce compliance with the requirements of this chapter, may exempt such ships from those requirements, provided that they comply fully with the provisions of: .1

the rules annexed to the Special Trade Passenger Ships Agreement, 1971; and

.2

the rules annexed to the Protocol on Space Requirements for Special Trade Passenger Ships, 1973. Regulation 2 Definitions

For the purpose of this chapter, unless expressly provided otherwise: 1 Subdivision length (Ls) of the ship is the greatest projected moulded length of that part of the ship at or below deck or decks limiting the vertical extent of flooding with the ship at the deepest subdivision draught. Regulation 2.1 Subdivision length (Ls) – Different examples of Ls showing the buoyant hull and the reserve buoyancy are provided in the figures below. The limiting deck for the reserve buoyancy may be partially watertight. The maximum possible vertical extent of damage above the baseline is ds + 12.5 metres.

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2

Mid-length is the mid-point of the subdivision length of the ship.

[Coordinator’s Note post SLF 53 – WG agreed that R2.2 can now be deleted so all subsequent Reg. numbers need adjusting and cross-references checked]. [Q2]

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[Coordinator’s Note for SLF 54 – see Q66D for a proposal to move the definition of “amidships” from R2.26 to R2.2, thereby removing the need to alter the numbering. There was an 11-1 majority in favour – to be finally agreed at SLF 54.] 2

Amidship is at the middle of the length (L). [Proposal to move Reg. 2.26 to Reg. 2.2 to replace deleted definition of “mid length”.] [Q66 – see under 2.26, below]

32

Aft terminal is the aft limit of the subdivision length.

43

Forward terminal is the forward limit of the subdivision length.

54 Length (L) is the length as defined in the International Convention on Load Lines in force. 65 Freeboard deck is the deck as defined in the International Convention on Load Lines in force. Regulation 2.6 2.5 Freeboard deck – See Explanatory Notes for regulation 13-1* for the treatment of a stepped freeboard deck with regard to watertightness and construction requirements. * References to regulations in these Guidelines are to regulations of SOLAS chapter II-1, unless expressly provided otherwise.

76 Forward perpendicular is the forward perpendicular as defined in the International Convention on Load Lines in force. 87 Breadth (B) is the greatest moulded breadth of the ship at or below the deepest subdivision draught. 98 Draught (d) is the vertical distance from the keel line at mid-length amidships [Q2] to the waterline in question. Regulation 2.9 (ref. SLF 52/17/6 - Norway) The definition of draught was transferred from the previous chapter. Since the calculations in old part B-1 were to be carried out at even keel the longitudinal position of “mid-length” had no practical implication, but this is no longer the case. The revised chapter requires that additional calculations must be carried out at ds and dp if the anticipated operational trim range exceeds +/-0.5% of Ls. According to its definition the aft terminal of the subdivision length Ls can be located a substantial distance aft of the aft perpendicular according to the load line length (L) and the aft terminal of the conventional length between perpendiculars (LBP) often preferred by yards and designers. The latter is normally referred to in the ship’s hydrostatic particulars. As a result the mid-length draught at Ls will often differ from the draught at the load line mark and from the longitudinal reference point assumed in the stability manual for trimmed waterlines. The nominal value of a trim measured over Ls will then also differ from the trims assumed in the stability booklet. This inconsistency should be rectified. Ls is primarily a calculation parameter used in Part B-1 and can easily be replaced in

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other contexts where consistency with intact stability calculations is important. Since practices on the definitions of LBP may vary it is proposed as a compromise that “draught” in the regulations is referred to length (L) in the future by amending paragraphs 9 and 13 as follows: Draught (d) is the vertical distance from the keel line at mid-length on length (L) to the waterline in question. R2.2 Definition of mid-length R2.9 Definition of draught Q2. Do you agree with the underlined addition to the definition of draught? Yes

Japan, MI, Norway, Spain, Denmark, US, Sweden

China, Finland, Germany, CLIA, Italy, UK No Comments / Alternative Proposals?:China: Regarding definition of draught: The draught (dl, dp and ds) used in the calculation of Index A should be the same for all trims. Mean draught cannot achieve this. However, correspondent draft (i.e. the draught corresponding to level trim) under a constant displacement doesn’t vary with the floating status. Therefore China proposes to revise paragraph 9 as follows: “9 draught (d) is the vertical distance from the keel line to the waterline at level trim.” This revision implies that 3 draughts (dl, dp and ds) defined in paragraph 10, 11 and 12 should be determined at level trim. And this also can resolve the problems mentioned by Norway. Finland: Prefer to add “on length (LBP)” to avoid differences between Ls and L (Load Line). All stability documents are done to refer length between perpendiculars including also input data in stability loading computer. Clear definition of LBP is needed to insert under reg. 2. Germany: We prefer that “LBP” (length between perpendiculars) shall be used as this is a preferable approach to address this important information to the crew and to ensure “operational compliance”. At the same time a clear definition of LBP is needed. CLIA: No need. Lg is OK! Italy: Length between perpendiculars “LBP” is preferable for operational purpose. Spain: We can accept the proposal, but, in that case we think that more modifications (as proposed in other parts of this document) are needed. We think that all of these changes should be evaluated jointly: -

-

Regulation 2.2 (Mid-length definition) should be deleted or changed. The trim definition and the limits should be adjusted also (according proposal contained in Q3): Clarification: In S2009 trim is the difference between the draught forward and the draught aft, where the draughts are measured at the forward and aft terminals respectively, disregarding any rake of keel. If the draught definition is changed, then the new draught is the vertical distance at mid-length on length (L), but it is not equal to the average of draught forward and the draught aft, measured at the forward and aft terminals. In other words, d ≠ Aft/Fore draught ± Trim / 2. That is why we agree with proposal of Norway (see Q3). To be consequent, trim limits should be changed accordingly. It should be referred to +/0.5% of L (instead of Ls).

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-

As per Norway proposal (SLF 52/17/6), for consistency Ls should then be replaced by the load line length L in other regulations.

US: However, isn’t the mid-length of L already defined as “amidships”? Suggest changing to: “Draught (d) is the vertical distance from the keel line at amidships to the waterline in question.” Also, not sure if the definition of “mid-length” is now needed; is it used anywhere other than in the definition of draught? Round 1 Discussion: The current definition of draught (d) is that it is the vertical distance from the keel line at mid-length (defined in Reg 2.2 as the mid-point of the subdivision length, Ls) to the waterline in question. Norway is concerned that there may be some confusion between the draughts and trims used in the damage stability calculations and those in the intact stability as used in the Stability Book. The aft terminal on Ls can differ considerably from the AP on L or LBP. Norway proposes to solve this by specifying that draught “d” be measured at the mid-length “on length (L)”. For consistency they propose a similar amendment in the definition of trim (Reg. 2.13 – see Q3). A problem with Norway’s proposal is that the term “mid-length” is already defined in 2.2 relative to Ls. The current trim definition refers to the aft and forward terminals, also relative to Ls. So “mid-length” referring to L, as proposed, could be confusing. The US suggests that there is already a definition for amidships at the middle of the length (L) (See Reg. 2.26) and proposes to use this in a new definition (above). Spain and the US question whether the Reg. 2.2 definition of mid-length is needed at all. China tries to avoid the problem by removing all references to amidships or mid-length but there may be a problem here with rake of keel vessels where the midships reference point for draught needs to be defined. Several correspondents express a preference for use of LBP. If LBP is the same as L (is there a difference?) and we use the US proposal then it seems we could reach agreement. The remaining question then would be whether to remove Reg 2.2 altogether and re-number the remaining regulations or just leave it there serving no purpose. Q2A. Recognising that Norway has identified a possible source of confusion over the definition of draught in Reg 2.9 and also that we need consistency throughout in the use of L and Ls, can we accept the US’ proposed revision of 2.9 as follows?:“Draught (d) is the vertical distance from the keel line at amidships to the waterline in question.” Yes MI, US, Japan, RINA, Norway (but with comment), CLIA, UK (with comment), Sweden Germany, Finland (with comment), Italy (with comment), France (with No comments), Denmark Comments / If “Yes” should we delete existing regulation 2.2 which is not used anywhere else and re-number the remaining regulations (cross-referencing checks will be needed) / Alternatives? MI: Agree (to delete Reg 2.2 etc ). Germany: No, we still prefer LBP and the corresponding trim and draft. China: Draught at amidships equals to mean draft which may be have multiple value as it varies with trim. In order not produce multiple draught, correspondent draught, or draught at LCF, of ds, dp and dl should be used in damage stability calculation. Therefore China would like to suggest a slight change to the wording proposed by US as follows: “Draught (d) is the correspondent draught which is the vertical distance from the keel line at

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amidships to the waterline in question.” Finland: All delivery documents (draught and trim) related to stability are based on LBP. Also software in loading computers is based on LBP. Crew are familiar with LBP (between perpendiculars). US: Yes [delete Reg. 2.2 and renumber the rest]. Italy: LBP is preferred. Stability manuals are referring to LBP, which is not the same as L (which is defined in the Load Line Convention). RINA: Agree that regulation 2.2 could be deleted. France: A common reference must be used for all stability documents. When ship is trimmed, draft will be different depending on mid-length definition, for a given waterline, but this will not influence calculation results. So France proposes to measure the draft at mid length between design perpendiculars which seems to be the current practice. A way may be to modify reg 2.2 and 2.9 as follows : 2 Reference point is the mid-point of design length between points where are calculated fore and aft drafts reported in stability documents. 9 Draught (d) is the vertical distance from the keel line at reference point to the waterline in question. Norway: Yes, but 2.2 should rather be harmonized with ICLL-66, i.e. “Amidships is the middle of the length (L)”. The mean draught will then be measured in the same longitudinal location as the load line mark. Our proposal was based on the anticipation that it may prove difficult to agree on a universal definition of LBP that will be enforceable due to different local traditions and practices on designer level. UK: The use of “mid-length” was needed for the old regulations where the assumed distribution density of damage location centre was not uniform, whereas the harmonised regulations assumed that the factor “a” to be uniformly distributed, therefore this definition is no longer needed. Should the above said distribution function be modified in the future to account for historical changes to come, there is no guarantee that “mid-length” to mark a bi-linear function might be employed. Round 2 Discussion: It seems that the UK has provided us with a very good reason to delete Reg. 2.2. China’s proposal to define “d” as draught at LCF (correspondent draught) would seem to be difficult to apply as LCF varies with draught – but perhaps we have not understood the proposal correctly? We also don’t quite understand Norway’s comment as the definition they quote - “Amidships is the middle of the length (L)” – is already included as Reg. 2.26. Several members still prefer to use “LBP” rather than “L”. It seems that we could probably all agree to the US proposal - “Draught (d) is the vertical distance from the keel line at amidships to the waterline in question.” – with amidships as defined in Reg. 2.26 and with Reg. 2.2 deleted if only we could agree that “LBP” and “L” are the same. The advantage of using “L” from the ICLL is that it is very clearly defined, with diagrams and explanations, even covering raked keel vessels (ref. Res. MSC.143(77) Reg. 3) . We have already referred the definition of forward perpendicular (Reg. 2.7) to the ICLL definition and our definition of amidships in Reg. 2.26 is the same as in the ICLL. The ICLL definition of “perpendiculars” (Ref. MSC.143 reg. 3.2) reads:“The forward and after perpendiculars shall be taken at the forward and after ends of the length (L). The forward perpendicular shall coincide with the foreside of the stem on the waterline on

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which the length is measured.” We don’t really understand why, as Italy and many others state, “Stability manuals are referring to LBP, which is not the same as L (which is defined in the Load Line Convention).” Maybe it is something to do with the A.P. definition – azipods, for example? Perhaps we should discuss this at SLF 53 and if we cannot agree that L is the same as LBP we may need to revise the definitions of Regs. 2.2 and 2.9 as proposed by France. Q2B (for SLF53 WG). Can we agree that L as defined in ICLL is the same as LBP as commonly used in industry? Consistency needed with Reg. 2.13 on trim (see Q3). Yes No Comments / If “yes” can we then agree to the US’ proposed revision of Reg. 2.9, the deletion of Reg. 2.2 and the consequent re-numbering of Regs. 2.3 to 2.26? / Alternatives? After discussion, the US’ proposals were agreed to by the SLF 53 WG. Q2. Recommend acceptance at SLF54 but the re-numbering may not be necessary (see Q66). 10 9 Deepest subdivision draught (ds) is the waterline which corresponds to the summer load line draught of the ship. 11 10 Light service draught (dl) is the service draught corresponding to the lightest anticipated loading and associated tankage, including, however, such ballast as may be necessary for stability and/or immersion. Passenger ships should include the full complement of passengers and crew on board. [Coordinator’s Note:- New question for SLF53 WG: For ro-pax ships do we include full passengers but no cars? It does not seem logical as most ro-ro passengers come with their cars.] [Coordinator’s Note post SLF 53 – we can’t recall what was decided in WG3 – therefore guess that no clarification is necessary].

Regulation 2.11 2.10 Light service draught (dl) – The light service draught (dl) represents the lower draught limit of the minimum required GM (or maximum allowable KG) curve. It corresponds, in general, to the ballast arrival condition with 10% consumables for cargo ships. For passenger ships, it corresponds, in general, to the arrival condition with 10% consumables, a full complement of passengers and crew and their effects, and ballast as necessary for stability and trim. The 10% arrival condition is not necessarily the specific condition that must be used for all ships, but represents, in general, a suitable lower limit for all loading conditions. This is understood to not include docking conditions or other non-voyage conditions. R2.11 EN Comments received from CLIA/CCSF between round 1 and 2: During ballast water exchange procedures it might happen that the resulting draught will be lower than the light service draught dl. It should be made clear that such temporary conditions are not to be used for the definition of the light service draught. Additional explanation: Any conditions, which result to a lower draught as the 10% arrival conditions due to ballast water exchange procedures, are not to be taken as dl

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Coordinator’s Comments: If we accept this addition to the EN, we would suggest slight improvements to the wording for clarity:Any conditions, which result [to] [in] a [lower] draught [as] [lower than] the 10% arrival conditions due to ballast water exchange procedures, are not to be taken as dl. CG Member’s Comments?:MI: No objection to this addition to the EN, concur with the co-ordinator’s re-draft. Germany: Acceptable. China: Ballast water exchange conditions as well as any other conditions which are not a recognized typical voyage condition are never used in the damage stability calculation. Finland: OK. US: We can accept this addition to the EN (as improved). RINA: Supports the text proposed by the Coordinator. France: Agreement on this addition to the EN with à wording as : “Any conditions, which result in a draught lower than the 10% arrival conditions due to ballast water exchange procedures, are not to be taken as dl.” Norway: Support the suggestion from the coordinator. CLIA: Agree. UK: Agreed, as coordinator’s comments. Round 2 Discussion: All who responded agreed to this improvement to the EN as amended by the co-ordinators. So Reg. 2.11 EN would now read as follows:Regulation 2.11 Light service draught (dl) – The light service draught (dl) represents the lower draught limit of the minimum required GM (or maximum allowable KG) curve. It corresponds, in general, to the ballast arrival condition with 10% consumables for cargo ships. For passenger ships, it corresponds, in general, to the arrival condition with 10% consumables, a full complement of passengers and crew and their effects, and ballast as necessary for stability and trim. The 10% arrival condition is not necessarily the specific condition that must be used for all ships, but represents, in general, a suitable lower limit for all loading conditions. This is understood to not include docking conditions or other non-voyage conditions. Any conditions which result in a draught lower than the 10% arrival condition due to ballast water exchange procedures are not to be taken as d l.

CONCLUDED - PROPOSAL ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53. (See SLF 53/14 para 12.1). Co-ordinator’s Note post SLF 53 – although initially approved in plenary, CLIA’s proposal was not accepted following discussion in the WG and was therefore deleted in SLF 53/WP.6. However, we recall that in the WG, final resolution of the wording of Reg. 2.11 EN was to be decided when we discussed changes to Regulation 5.1. Due to time constraints this did not happen, therefore it is proposed that we re-visit this paragraph in the CG. Co-ordinator’s Note for Round 4 Questionnaire – we will leave this question for the moment and consider it again when we look at the critical KG/GM questions (Q20 etc) in round 5. Co-ordinator’s Note for SLF 54 – see SLF 54/8/1 para. 14.1. This EN to be reviewed in the light of Norway’s proposed revisions (see Annex 2 of SLF 54/8/1).

12 11 Partial subdivision draught (dp) is the light service draught plus 60% of the difference between the light service draught and the deepest subdivision draught.

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13 12 Trim is the difference between the draught forward and the draught aft, where the draughts are measured at the forward and aft terminals perpendiculars respectively, as defined in the International Convention on Load Lines in force, [Q3] disregarding any rake of keel. Regulation 2.13 (ref. SLF 52/17/6 - Norway) Norway proposes to change 2.13 to:- [See also comments under regulation 2.9]. Trim is the difference between the draught forward and the draught aft, where the draughts are measured at the forward and aft terminals of length (L) respectively, disregarding any rake of keel.

R2.13 Definition of Trim Q3. Do you agree with the underlined addition to the definition? Yes

Japan, MI, Norway, Italy, Spain, Denmark, US, Sweden

No

China, Finland, Germany, CLIA, UK

Comments / Alternative Proposals?:China: Definition of Trim need not be changed as trim measured based on Ls, LBP or L is not significant as the waterline is the same, the Longitudinal trim angle is also the same; the hydrostatic parameters under the waterline, such as LBP and KMT won’t be influenced by the trim definition. If the trim should be revised, the most appropriate is based on LBP. Finland: Refer to Q2. Germany: See comments on Q2 CLIA: No need. Italy: See also Q2. Spain: See comments to Q2. An alternative text could be as follows (anyway we can accept also Norway proposal): “Trim is the difference between the draught forward and the draught aft, where the draughts are measured at the forward and aft perpendiculars respectively, as defined in the International Convention on Load Lines in force , disregarding any rake of keel”. Denmark: Please note that the definitions of aft and forward terminals in Reg. 2.3 and Reg. 2.4 are based on the subdivision length. US: Since “forward terminal” and “aft terminal” are defined terms, in this definition suggest changing to “forward and aft limits” as is used in the definition of forward/aft terminal. Round 1 Discussion: As mentioned in the discussion for Q2, Norway’s proposal could introduce a slight inconsistency by associating “terminals” with “L”, which in 2.3 and 2.4 are defined in relation to “Ls” (as stated by Denmark & US). The US proposal of replacing “terminals” with “limits” would be more consistent but could also be slightly ambiguous as the word “limit” may not be readily associated with “L” by the user (see 2.3 and 2.4). Spain’s proposal overcomes this problem and is very specific. China’s comments are appreciated but if trim is defined as a difference in draughts measured at two reference points then those points must be defined; it is agreed that trim angle is independent of any defined reference points but is, we believe, not commonly used in stability books. There does not appear to be a definition of “trim” in the 2008 IS Code. Q3A. Recognising that Norway has identified a possible source of confusion over the definition of trim and that there seems to be a majority in favour of defining trim over length L (or LBP) to be consistent with the stability book, do you prefer the US proposal to replace “terminals” by “limits” or the more specific proposal by Spain:“Trim is the difference between the draught forward and the draught aft, where the draughts are

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measured at the forward and aft perpendiculars respectively, as defined in the International Convention on Load Lines in force, disregarding any rake of keel”. ? US Italy (with comment), France (with comment), Norway (with comment) proposal? Spain’s proposal?

MI, Finland, US, Japan, RINA (with comment), CLIA, UK, Sweden, Denmark

Comments / alternative proposals? MI: Prefer the proposal by Spain. Germany: No – should refer to LBP (and not to L from LoadLine). China: The above proposed text of trim definition is based on the length as defined in Reg.3 of the LL Convention. Normally in the stability booklet the draughts at terminals as defined in Load Line Convention are usually not calculated. However the normally used draft is based on LBP. This LBP is usually found in the Lines Plan and is quite different from the length as defined in Reg.3 of the LL Convention. Italy: US proposal, but using LBP instead of L, as explained in Q2A RINA: Forward and aft terminals are defined in regulation 2 and are associated with the definition Ls. In certain ship arrangements it is possible that the forward/aft terminals limits can be positioned at the extremes of the ship structure see EN regulation 2.1 Figure. In such cases these positions will not be suitable for positioning draught marks. France: Definition of the reference length has a slight influence on actual trim limits. Reference to a well defined length as freeboard length may be preferable to reference to LBP which may be subject to designer choice. Norway: We agree that “terminals” in our proposal might be misleading and the US proposal is supported. Round 2 Discussion: There is a majority of 9 to 4 in favour of Spain’s proposal. We all now seem to agree that trim should be measured over length LBP (or L) and not Ls. But we must await the outcome of our discussions under Q2 to resolve the issue of the exact difference between L and LBP (Germany, Italy, China and France mention the difference here once again). If we could agree that L and LBP are the same then presumably we could use Spain’s proposal. The US proposal has some support but perhaps use of the term “limits” rather than “terminals” may be preventing more members from supporting it as it may still be associated with the use of “limits” in Reg. 2.3 & 2.4 referring to Ls. Q3B (for SLF53 WG). If we agree that L and LBP are equivalent (see Q2) can we then use Spain’s proposal for Reg. 2.13 - “Trim is the difference between the draught forward and the draught aft, where the draughts are measured at the forward and aft perpendiculars respectively, as defined in the International Convention on Load Lines in force, disregarding any rake of keel.” - ? Yes No Comments / Alternatives? Spain’s proposal was accepted in WG3 at SLF 53. Q3. Recommend acceptance at SLF54 14 13 Permeability (μ) of a space is the proportion of the immersed volume of that space which can be occupied by water. [Coordinator’s Note: There is a new IACS Unified Interpretation (UI) for this definition to be presented at MSC 87 in May 2010 - “In determining the permeability of a space, the volume of a space should be taken as the moulded volume, i.e. the immersed volume of a space should be the underwater moulded volume of that space multiplied by the permeability.” (Ref SLF 52/19, Annex 4).

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New Note: The UI was accepted at MSC 87 ref MSC87/26/12.12:- ]

New EN for R2.14? Definition of permeability. Q4. If accepted at MSC 87, should this UI be included as a new EN? Yes No

China, Finland, Germany, Japan, Norway, Italy, Spain, Denmark, UK, US, Sweden CLIA

Comments / Alternative Proposals?:MI: If accepted then this definition could be updated rather than adding a new EN. CLIA: Adds nothing and is confusing. Round 1 Discussion: Apart from CLIA and MI, a large majority agreed to include this (now approved) UI in the EN. We could ask CLIA and MI to accept the majority verdict but perhaps the MI suggestion has merit. For example we could simply add “moulded” to the definition in the regulation:Permeability (μ) of a space is the proportion of the immersed [moulded] volume of that space which can be occupied by water. Would this make it clear enough to the user that the volume to be used in the damage calculations is (the gross volume less an allowance for internal structure) * (μ) without needing a new EN? Q4A. If we accept the majority view, should we add the IACS UI to the EN without change or should we modify the definition of permeability in Reg 2.14 as proposed by MI (perhaps by adding “moulded” as shown, for example)? Add UI as Germany, China, Finland, Japan (with comment), RINA, France (with new EN? comment), UK, Sweden, Denmark Modify Reg 2.14?

MI, US, Italy, Norway, CLIA

Comments / Alternative suggestions for changing the wording of the definition? MI: Modify Reg. 2.14 as proposed. Japan: Japan does not have a strong position. France: Both alternatives seem equivalent. Round 2 Discussion: There is a majority of 9 to 5 in favour of adding the IACS UI to the EN. The co-ordinators have had some discussions with UK industry who say the UI is clearer. Q4B (for SLF53 WG). Can we accept the majority view to include the IACS UI for permeability in a new EN for Reg. 2.14? Yes No Comments? This proposal was not accepted by WG3 at SLF 53 so the regulation remains unchanged and no EN is deemed necessary. NFA at SLF 54. 15 14 Machinery spaces are spaces between the watertight boundaries of a space containing the main and auxiliary propulsion machinery, including boilers, generators and electric motors primarily intended for propulsion. In the case of unusual arrangements, the Administration may define the limits of the machinery spaces.

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16 15 Weathertight means that in any sea conditions water will not penetrate into the ship. 17 16 Watertight means having scantlings and arrangements capable of preventing the passage of water in any direction under the head of water likely to occur in intact and damaged conditions. In the damaged condition, the head of water is to be considered in the worst situation at equilibrium, including intermediate stages of flooding. 18 17 Design pressure means the hydrostatic pressure for which each structure or appliance assumed watertight in the intact and damage stability calculations is designed to withstand. 19 18 Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which [passenger and or crew – change in red agreed at SLF 53 but see coordinator’s comment under CLIA Q1 below] [passenger and crew][CLIA Q1D(1)] evacuation will not be impeded by water in any stage of flooding for damage cases [defined in regulation 8 and in part B-2 of this chapter] [CLIA Q1D(2)]. [For passenger ships, “evacuation” refers to both passengers and crew in all regulations.] [CLIA Q1D(1)]. The bulkhead deck may be a stepped deck. In a cargo ship the freeboard deck may be taken as the bulkhead deck. [In a cargo ship the freeboard deck may be taken as the bulkhead deck.][Q6D(1)]

R2.19 Definition of Bulkhead deck CLIA Q1 Queries received from CLIA/CCSF between Round 1 and Round 2: Regulation 2.19 How to apply this to Ro-Pax vessels, where the bulkhead deck is the car deck where no passengers are staying during a voyage? Coordinator’s Comments: CG Member’s Comments?:Germany: to be precise, the definition of the bulkhead deck should read: … lowermost deck from which passenger and/or crew evacuation… China: No comments. Finland: In Ro-Pax vessels watertight bulkheads are extended up to bulkhead deck, but no evacuation. Critical openings for evacuation routes from below bulkhead deck are located at least 2.4 m above bulkhead deck. ==> bulkhead deck is alternatively and/or lowermost deck. RINA: There appears to be no justification for assigning the uppermost deck in a passenger ship as the bulkhead deck. It is proposed that regulation 2.19 is amended as follows: 19. Bulkhead deck in a passenger ship means [any] [the uppermost] deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which passenger and crew evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and in part B-2 of this chapter. The bulkhead deck may be a stepped deck.

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In a cargo ship the freeboard deck may be taken as the bulkhead deck. France: In this case only crew members may have to be evacuated, but the same principle is to be applied. For clarification, the wording of reg 2.19 may be modified to “…passenger or crew evacuation…” Norway: The regulation refers to passengers and crew, so evacuation of crew will still be relevant. Round 2 Discussion: It seems that the best solution to the problem raised by CLIA would be to change the regulation as highlighted below in square brackets:19 Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which passenger [and/or] crew evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and in part B-2 of this chapter. The bulkhead deck may be a stepped deck. In a cargo ship the freeboard deck may be taken as the bulkhead deck. As co-ordinators we cannot see how RINA’s proposal improves the clarity. The definition must link the top of the watertight bulkheads to the highest deck to which the bulkheads are carried not just any deck – the WT bulkheads also carry to the lower decks but this is not the important point. But we will nonetheless ask the member’s opinion. CLIA Q1 (for SLF53 WG). Can we accept the change to Reg. 2.19 as highlighted in square brackets in the Round 2 discussion above or do we prefer RINA’s proposal? Prefer “and/or”? Prefer RINA’s proposal? Comments? Co-ordinator’s Note post SLF 53:- In WG3 at SLF 53, the RINA proposal was not accepted but it was agreed to change the text in square brackets to read “or” rather than “and/or”. Since the meeting we wondered whether it would be better to simply delete “passenger or crew” altogether leaving us with “… the lowermost deck from which evacuation will not be impeded …….”. CLIA Q1C (for Round 4 questionnaire). If we are permitted to alter a decision made at the SLF 53 WG, would you prefer Reg. 2.19 to read:(a) Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which passenger or crew evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and in part B-2 of this chapter……. or (b) Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which passenger or crew evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and in part B-2 of this chapter……

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Prefer (a)

US, Norway, France, Germany, Spain, EC (but not a strong preference. In any case it should be understood that evacuation concerns both passengers and crew), UK (assure uniform implementation by explicitly stating the obvious). Prefer (b) Vanuatu, Sweden, Japan, China, Denmark, Finland, Italy, CLIA, MI (agree the clarity of the text in option (b)) Comments? Vanuatu: (b) is more understandable, less likely to be subject to interpretation. Will (or perhaps there was some prior discussion) there be further discussion on the word “impeded”, is this with respect to depth; or is the presence of any water the criteria? US: Option (a) provides absolute clarity and is unambiguous; option (b) does not and will inevitably be questioned. (i.e. option b would eventually spawn an EN) RINA: No comments at this time. Germany: Option (a) may be more specific and thus may avoid possible future discussions about whether or not crew is also addressed. France: The 2 proposals are almost identical. Round 6 Discussion: Voting is close – 7 favour option (a) although France and the EC express no real preference and 9 favour (b) with 1 neutral. US, UK and Germany firmly believe that (a) provides greater clarity although Vanuatu and MI each prefer (b). On reflection, the co-ordinators now think that (a) may be preferable because there is a danger that crew evacuation in a passenger ship could otherwise be disregarded if it is not specifically mentioned. However, there are other places in the Regulations and EN where the term “evacuation” is used without specifying passenger or crew (for example Reg 7-2.5.2.2 and EN). Perhaps we should make it clear in every regulation / EN or alternatively define “evacuation” in Reg. 2.1918 as always referring to passengers and crew? Vanuatu asks whether “impeded” will be further discussed. We suggest that the EN for Reg. 7-2.5.2.2 makes it clear that partial immersion of the bulkhead deck may be accepted but no water at all is permitted on the evacuation routes (see diagram in EN 72.5.2.4). Is this sufficient explanation, Vanuatu? Perhaps some further clarification of “impeded” is needed in this regulation? This gives rise to another query from the co-ordinators. As it stands this definition specifies the bulkhead deck as being the “lowermost deck from which evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and part B-2 of this chapter.” The phrase in bold type specifies only the minor damage and bottom damage scenarios and not the majority of the side damage cases in Part B-1. Can anybody remember if this was a deliberate decision –– and if so why? To clarify “evacuation” throughout Ch.II-1 Part B we therefore propose the following compromise by altering Reg. 2.19 as follows:Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried watertight and the lowermost deck from which [passenger and crew] evacuation will not be impeded by water in any stage of flooding for damage cases defined in regulation 8 and in part B-2 of this chapter. [For passenger ships, “evacuation” refers to both crew and passengers in all regulations]. The bulkhead deck may be a stepped deck. In a cargo ship the freeboard deck may be taken as the bulkhead deck. CLIA Q1D. 1. Do you agree with the co-ordinators’ proposal to delete “passenger and crew” and add a clarifying sentence defining “evacuation”, similar to that highlighted in red in the discussion paper?

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2. Should the “lowermost deck” be determined only by consideration of damage cases defined in Reg. 8 and Part B-2? Q1 (Y/N)? Yes: Japan, CLIA, Finland, Norway, Germany (with comment), Poland, Italy, UK, France, Denmark No: RINA, US (No; we strongly prefer the “passenger and crew” option as that text is clear and simple. In addition, we do not believe it would be appropriate to insert a secondary definition of “evacuation” within the definition of bulkhead deck (nor do we think a definition of evacuation is necessary)), EC (No, the text is clear as it stands), China (Deleting “passenger and crew” is enough. There is no need to add a clarifying sentence.) Q2 (Y/N)?

Yes: Japan, Finland, Germany, US, Italy, France, Denmark (see comment), China No: CLIA, RINA, Norway, UK (We should consider ending the first sentence at “…and the ship’s shell are carried watertight” and deleting the rest of the sentence as we believe the current definition is confusing).

Comments? / Alternative wording? / Clarification of “impeded”? RINA: Q1. It is proposed that we keep passenger and crew (as this is applicable only to passenger ships) and that we include a new definition for evacuation which defines the evacuation process in two stages i.e. evacuation to muster stations and evacuation from the muster station to the lifesaving appliances. In both cases the definition of bulkhead remains the same. Q1. In the last sentence of 2.19 it is not understood why in a cargo ship the freeboard deck may be taken as the bulkhead deck. This is confusing, as far as we are aware the term bulkhead deck is not used anywhere on cargo ships. Q2. The lowermost deck should be determined by consideration of all damage cases in Part B-1 and B-2 Germany: The definition of the bulkhead deck is difficult to understand (… uppermost deck and … lower most deck …) and may lead to different interpretation, although the practical application does not show these difficulties at the moment. Poland: “And the lowermost deck from which any person will not be impeded by water in any stage of flooding for damage cases.” US: Regarding why the side damage cases from Part B-1 were excluded: We generally recall that it was to keep the definition simpler. If Part B-1 damages were included then a survivability level would have to be specified (i.e. s = [1]) because all damages are not required to be survivable. Regarding “impeded”: We agree that this means no water at all is permitted on the evacuation routes. No strong view on whether clarification is needed. France: Damage cases defined in reg 8 are the only damages for which it is mandatory not to immerse evacuation route. For other damage cases, survival factor will be null if evacuation route is immersed. So it will be necessary that evacuation routes will not be immersed for a sufficient number of damage cases to reach the required index, but there is no specific requirement for damage cases other than defined in reg 8. The word “impeded” may be not sufficiently clear. In reg 7-2 §5.2, it is specified that criterion is immersion of horizontal evacuation route and that this criterion is taken into account only with final waterline. Proposed wording may be : Bulkhead deck in a passenger ship means the uppermost deck at any point in the subdivision length (Ls) to which the main bulkheads and the ship’s shell are carried

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watertight and the lowermost deck from which [passenger and crew] horizontal evacuation routes will not be impeded by water in any stage of flooding immersed by final waterline for damage cases defined in regulation 8 in part B-2 of this chapter. [For passenger ships, “evacuation” refers to both crew and passengers in all regulations]. The bulkhead deck may be a stepped deck. In a cargo ship the freeboard deck may be taken as the bulkhead deck. However, explanatory note to regulation 7-2.5.2.2 should apply to this definition to specify what is an horizontal evacuation route and that only evacuation from undamaged spaces is to be considered. Denmark: Regarding Q2 the evacuation routes are already covered by the probabilistic calculations in Part B-1 as si should be taken as 0 if any part of the bulkhead deck in passenger ships considered a horizontal evacuation route or a vertical escape hatch, immerses (Reg. 72.5.2.2+5.3.1). For minor damages according to Reg. 8 and Part B-2 we must always be able to evacuate the ship hence the evacuation routes are not allowed to be immersed / impeded by water in those cases. CLIA Q1 Co-ordinator’s Note:- The variety of views mean that the wording of R2.19 must be resolved at SLF 54. See alternatives in square brackets above. DISCUSS AT SLF 54

Regulation 2.19 2.18 Bulkhead deck – See Explanatory Notes for regulation 13 for the treatment of a stepped bulkhead deck with regard to watertightness and construction requirements. 20 19 Deadweight is the difference in tonnes between the displacement of a ship in water of a specific gravity of 1.025 at the draught corresponding to the assigned summer freeboard and the lightweight of the ship. 21 20 Lightweight is the displacement of a ship in tonnes without cargo, fuel, lubricating oil, ballast water, fresh water and feedwater in tanks, consumable stores, and passengers and crew and their effects. 22 21 Oil tanker is the oil tanker defined in regulation 1 of Annex I of the Protocol of 1978 relating to the International Convention for the Prevention of Pollution from Ships, 1973. 23 22 Ro-ro passenger ship means a passenger ship with ro-ro spaces or special category spaces as defined in regulation II-2/3. 24 23 Bulk carrier means a bulk carrier as defined in regulation XII/1.1. 25 24 Keel line is a line parallel to the slope of the keel passing amidships through: .1

the top of the keel at centreline or line of intersection of the inside of shell plating with the keel if a bar keel extends below that line, on a ship with a metal shell; or

.2

in wood and composite ships, the distance is measured from the lower

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edge of the keel rabbet. When the form at the lower part of the midship section is of a hollow character, or where thick garboards are fitted, the distance is measured from the point where the line of the flat of the bottom continued inward intersects the centreline amidships. 26 25 Amidships is at the middle of the length (L).

R2.26 (Move definition of “amidships” to replace deleted R2.2 – “mid-length”) New proposal from co-ordinators for Round 6. Would it be sensible to move the definition of “amidships” from 26 25 to replace the deleted definition 2 for “mid length”? This preserves the existing numbering (apart from 27 26) thus minimizing any crossreferencing problems and ensuring that “amidships” is defined before it is first used in definition 9 8 (for “draught”). Q66D (for Round 6 Questionnaire). Do you agree with the above proposal? Yes?

Japan (see comment), CLIA, RINA, Finland, Norway, Germany, Poland, US, Italy, UK, EC, France, Denmark China

No?

Comments? Japan: It should be noted that displacement of initial condition with trim will be changed due to this amendment of the length. Because, the position measuring draught is changed from the middle of Ls to the middle of Lf. Therefore, this revision may affect Attained Index of some ships. Poland: It will ensure that “amidships” is defined before it is first used in def. 9 for draught. Q66 Members voted 11-1 in favour, China opposes, Japan has a comment. Can we accept majority at SLF 54? 27 26 2008 IS Code means the International Code on Intact Stability, 2008, consisting of an introduction, part A (the provisions of which shall be treated as mandatory) and part B (the provisions of which shall be treated as recommendatory), as adopted by Resolution MSC.267(85), provided that: .1

amendments to the introduction and part A of the Code are adopted, brought into force and take effect in accordance with article VIII of the present Convention concerning the amendment procedures applicable to the Annex other than Chapter I: and

.2

amendments to part B of the Code are adopted by the Maritime Safety Committee in accordance with its Rules of Procedure.

[Co-ordinators Note:- The sentences highlighted were not contained in the 2009 Consolidated Edition and come from resolution MSC.269(85)]. [27][28] [Dry cargo ship is a cargo ship of any size but excluding oil tankers and vessels covered by the IBC and IGC Codes.] [Q6D(2)] [28][29] [Small dry cargo ship is a dry cargo ship with 24 80 m. We think that the reference to B-1 and to B-2 should be maintained in the main text (the problem regarding the application of regulation 9.8 to cargo ships with L> 80 m other than tankers could be clarified in the footnote). It is acceptable to delete parts B-3 and B-4 form the main SOLAS text. In relation to this, we agree with Norway proposal. For vessels with L ≥ 80 m, subject to other subdivision and damage stability regulations contained in other instruments developed by the Organization, we think that it is acceptable and logical to impose the application of regulation 9.8 in case of partial or total absence of the double bottom required by regulation 9, but only if the applicable instrument does not contain its proper bottom damage requirements. In relation to this, we agree with Norway proposal. Denmark: If the square brackets [through B-4] are deleted the bottom requirements in Reg. 9 will be applicable to all cargo ships, i.e. also cargo ships with a length lesser than 80 m. The applicability of the damage stability requirements in Reg. 9.8 has not been investigated for ships having a length less than 80 m. US: With this regulation revision the Explanatory Note for regulation 4.1 could be deleted (it was created to explain this “problem” in the regulation). Japan: Supports the proposal that the words “through B-4” be deleted because the current wording could lead to a misunderstanding that paragraph 9.8 is NOT applied to ships less than 80m. On the other hand, Japan also thinks that the regulations listed in footnote could be applied as alternative regulations in paragraph 9.8. (See also Q44.) Round 1 Discussion: Eleven are in favour of Norway’s proposal but Spain is partly opposed and Denmark is concerned that if it is adopted confusion may arise when applying Regulation 9 (“Double Bottoms in passenger ships and cargo ships other than tankers”) which could be interpreted as applying to cargo ships of all sizes, rather than only to those over 80 metres in L. Japan on the other hand thinks that Reg. 9.8 should be applied to cargo ships less than 80 m (a size which Denmark argues was not investigated when this part of SOLAS 2009 was written). Spain agrees with Denmark on this issue. We could possibly amend the footnote, as suggested by Spain, or even change the title of Regulation 9 to “Double Bottoms in passenger ships [regardless of length] and cargo ships other than tankers [having L >= 80 metres]” to overcome this problem. Japan has also prepared extensive proposals regarding Reg. 9.8 and the associated EN, which we can consider under Q44, below. Japan proposes that Reg. 9.8 could be met by alternatively demonstrating compliance with the regulations listed in the footnote to Reg. 4.1. US suggests that if we adopt Norway’s proposal it should be possible to remove the table in the EN for the footnote to Reg. 4.1 which was inserted to clarify the applicability of specific regulations in parts B1, B2 and B4 to the ship types listed in the footnote.

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To summarize, we could 1) adopt Norway’s proposal; 2) clarify that Reg 9.8 only applies to cargo ships >= 80 m by adding [having L >= 80 metres etc] to the title to Reg. 9 (or changing the footnote); 3) Delete the Table in the EN to footnote 4.1 as proposed by the US. However, this proposal, if accepted, would not satisfy Japan’s view that Reg. 9.8 should apply to cargo ships with L < 80 m. Q6A. Can we accept Norway’s proposal to delete “through B-4” as long as we clarify somewhere that Reg. 9.8 does not apply to cargo ships with L < 80 m and so delete the Table in the EN to footnote 4.1, as suggested by the US? Yes

MI (agree this action), Finland, US (with comments), Italy, France (with comments), CLIA, UK, Sweden, Denmark No Germany (with comments), RINA (with comments), Norway (with comments) Comments (particularly on whether or not Reg. 9 should apply to cargo ships with L < 80 m) / Alternatives:MI: Reg.9 should not apply to cargo ships of L < 80 m. Germany: We are of the position that the requirement for fitting a watertight double bottom is applicable for all cargo vessels, including vessels with a length less than 80m. China: (1) Support to delete “through B-1” [Note: presume this should read B-4, China?] (2) Clarification is needed to be made that Reg.9 (including Reg.9.8) should apply to cargo ships with L < 80 m and the probabilistic damage stab. Requirement of reg.5-1, 6, 7, 7-1, 7-2 and 7-3 should apply to cargo ships with L≥80m. US: Regulation 9 should apply to cargo ships with L < 80 m; this basic application to all SOLAS cargo ships is not changed from previous regulation 12-1. Regarding the specific application of reg 9.8, this is new and the impact on cargo ships with L < 80 m is not clear (and should be further considered). Japan: Before SOLAS 2009, the regulation regarding double bottom for cargo ships applied ALL cargo ships other than tankers, including ships with L 24 or L>80 m?

To be discussed by the new SDS CG for SLF 54 (Ref: SLF 53/WP.6 paragraphs 25 and 26 and TOR 32.5)

Q6C (for round 4 questionnaire). Having made the decisions highlighted above at SLF53 the issue of the size of cargo ship to which Part B-2 applies was referred back to our 2011 CG. Therefore, could you please state whether you think that Part B-2, which includes the DB regulations, should apply to cargo ships of 24 m L and upward or only to 80 m L and upward?

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Also, the proposal for a footnote to Part B-2 to clarify the applicability of these regulations was rejected by the WG at SLF 53. However, it would seem that in view of the newly agreed footnote to Reg 4.1 which now only mentions Part B-1, some form of clarification of the applicability of Part B-2 is still needed somewhere – perhaps in the regulation title or by retaining the Table in the EN? Your comments are invited (see also Q10C). B-2 applies to cargo vessels with L>24?

B-2 only applies to cargo vessels with L>80?

Yes Norway, Japan, France, China, Germany (Generally yes, however the requirements for Reg. 9 may need to be adjusted to those small ships after further investigations), Finland, UK. No Vanuatu Neither US (see comments) RINA (If this was applied to cargo vessels then it would be applicable to ships which are less than 500 gross tons and could raise a conflict between the application of this Part and other Parts of SOLAS, which have an applicability criteria of 500 gross tons, or greater, for cargo ships. There is a requirement in Classification Rules which states that double bottoms need not be fitted in cargo ships less than 500 ton gross tonnage. Noting that a review of cargo ships is currently on the work program in hand at MSC, is it an option at this to forward this issue to DE for inclusion in their work program?). Yes Vanuatu, Italy RINA (While it is the case that Part B-2 could be applied to cargo ships greater that 80 m. However there are requirements in Part B-2, such as Regulation 12 Peak and machinery space bulkheads, shaft tunnels, which will surely be applicable to SOLAS cargo ships with a length less than 80 m. This may be the case for other paragraphs in Part B-2. It is considered that Part B-2 needs to be reviewed to provide appropriate regulation for cargo ships between 500 GT, and over, and ships with a length greater that 80 m. See comments in paragraph above). Spain (In relation with regulation 9.7 and 9.8 (damage stability requirements bottom damage) we prefer 80 m. The other regulations should be studied in a case-by case basis. Anyway, it is important to point out that a cargo vessel of 24 m length could have less than 500 GT (SOLAS common limit)). Continued….

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Where should we clarify which cargo vessels must comply with B-2?

Vanuatu: With respect to the double bottom issue we think this is less a question of applicability for vessel type(s) but more as a question of the impact on vessels designed to operate from shallower ports. We feel this would tend bloat draught without providing any quantifiable ‘improvement’ characteristics from the application of current rule. Otherwise Administrations will need the flexibility as for Regulation 9.5 for passenger ships; this however seems backwards (and a bit archaic). US: Suggested options: A. Insert a regulation 4.1bis as follows: 4.1bis Except where expressedly provided otherwise, .1 Part B-2 applies to passenger ships and cargo ships. .2 Part B-3 applies to passenger ships. .3 Part B-4 applies to passenger ships and cargo ships. B. The approach used in Parts C and D; a caption under the Part B-2 title: (Except where expressedly provided otherwise part B-2 applies to passenger ships and cargo ships); etc. The applicability should be clear in the regulations; an EN should not be necessary. We prefer option A. Note: this will all now need to be considered/combined in the context of MSC 89/22/8 and its proposed text. Japan: Japan does not have a strong position, but we suggest inserting new paragraph before current reg 9.1, ex; “1 This regulation applies to cargo ships of [24][80] m in length (L) and upwords other than tankers and to all passenger ships regardless of length. 2 A double bottom shall be fitted with ...” RINA: This should be clarified in Regulation 4. Denmark: (with comments). Germany: It’s already laid down in Reg. 4 as updated during SLF 53. We think it’s clear enough. But if the group finds it’s not, we would suggest putting it clearly in SOLAS, not in the EN. Italy: Regulation title. UK: To have a direct reference in the main regulation text would be preferable at this stage.

Further Comments?:Vanuatu: With respect we submit this not an issue that lends itself to global ‘one size fits all’ style absolutism since under SOLAS the options are limited to the binary set of Passenger vs Cargo vessel. Seeking to apply 9.8 extents of damage based on beam for beamy, shallow draught vessels under 80 meters will likely be remarkably disruptive of the design process. US: We do not believe there should be a cargo ship length threshold for Part B-2. Our understanding of the SLF 53 outcome was that Part B-2 was to be applied to all SOLAS cargo ships irrespective of length (see last sentence of SLF 53/WP.6 paragraph 25). The validity of applying regulation 9.8 to smaller ships was identified as a separate issue and highlighted for consideration as a SDS CG TOR. (see SLF 53/19, paragraphs 14.6 and 14.10.2) Note: we believe only regulations 13-1 and 15-1 have their origins in SOLAS 90 Part B-1 and any legacy connection to L>80. Under SOLAS 90, regulations 9, 10, 11, 12, 15, 16 and 16-1 applied to all cargo ships. Japan: The scope of reg.9.6 to 9.8 should be considered carefully because ships with L 24 m whilst keeping in mind that the double bottom requirement with regard to the damage extent and “s” level needs to

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be considered / further studied. We refer for example to tugs of 24 m and over and GT > 500. Round 6 Discussion: Many thanks for all your Round 4 comments – this is getting very complicated - let’s hope we can find a way through……! 1) Before going through your Round 4 responses, here is a summary of where the coordinators think we stand at the moment, bearing in mind the response from MSC 89 to the German / UK paper MSC 89/22/8:"22.33 The Committee considered document MSC 89/22/8 (Germany and the UK), proposing to develop amendments to SOLAS regulation II-1/4 in order to clarify the application of SOLAS subdivision standards to cargo ships which are complying with the subdivision standards of other IMO instruments, and agreed to include, in the 2012-2013 biennial agenda of the SLF Sub-Committee and the provisional agenda for SLF 54, a planned output on "Development of amendments to SOLAS regulation II-1/4 concerning subdivision standards for cargo ships", with a target completion date of 2013."

2) As mentioned in our covering e-mail to the Round 5 questionnaire on 6th July 2011, we propose to carry on updating Reg. 4.1 and all the remaining Part B regulations where necessary with the aim of completion at SLF 54 in January 2012 under the terms of the original ToR as specified in SLF 53/19 para. 14.10. There are good reasons for seeking an extension of this completion date to January 2013 (SLF 55), discussed elsewhere, but for the moment we will assume we must meet the original deadline. 3) We must now try to eliminate footnotes wherever possible by incorporating them into the text of the regulations and also reduce EN’s (e.g. the Table in the EN to Reg. 4.1) whilst we have this chance to change the regulations. We note the amendments proposed by Germany and the UK to Regulation 4 in the Annex to MSC 89/22/8 but we will regard these as proposals only as they ignore the changes already agreed at SLF 53 (shown below for easy reference). So we will somehow need to combine the text in the Annex to MSC 89/22/8 with the changes already agreed at SLF 53 (see proposals at end of this discussion). 1 The damage stability requirements in parts B-1 through B-4 shall apply to cargo ships of 80 m in length (L) and upwards and to all passenger ships regardless of length but shall exclude those cargo ships which are shown to comply with subdivision and 

damage stability regulations in other instruments* developed by the Organization. 1

In Part B-1,

.1 regulation 5 shall apply to passenger ships of all sizes and every cargo ship having a length (L) of 24 m and upwards (including tankers covered by MARPOL Annex 1, the IBC and IGC Code). .2 regulation 5-1 shall apply to passenger ships of all sizes and every cargo ship having a length (L) of 24 m and upwards including those vessels which are shown to comply with stability regulations in other instruments* developed by the Organization but shall not apply to tankers covered by MARPOL Annex 1, the IBC and IGC Code. .3 the remaining regulations in Part B-1 shall apply to passenger ships of all sizes and, with the exception of regulations 8 and 8-1, to cargo ships having a length (L) of 80 m and upwards but they shall not apply to any vessels which are shown to comply with subdivision and damage stability regulations in other instruments* developed by the Organization. Q6

_____________________ *

Cargo ships shown to comply with the following regulations may be excluded from the

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application of the damage stability regulations in part B-1: *

The following instruments and regulations contain stability requirements for cargo ships:-

4) The other main issues are that, having deleted the original text of Reg. 4.1 and replaced it with text to clarify the applicability of Part B-1, we nowhere, at the moment, specify the applicability of Parts B-2, B-3 and B-4 other than within the regulations themselves or in their titles. 5) For Part B-2, you may recall that there was a proposal made by the co-ordinators to try to define its applicability by means of a new footnote, with square brackets around [24] and [80], but this was rejected at SLF 53 as footnotes are now to be avoided where possible :[* The regulations in Part B-2 apply to passenger ships regardless of length and to cargo ships of [24][80] m in length (L) and upwards but shall not apply to those cargo ships which are shown to comply with subdivision and damage stability regulations in other instruments developed by the Organization (Ref. footnote to Regulation 4.1).]

5.1) We need to re-examine how and where to define the applicability of part B2. After further study we have found it is more complicated than the above footnote suggests. Some regulations in B-2 apply to “all” cargo ships, some to cargo ships of L= 80 m and upwards, some to passenger ships (including ro-pax) and some to ro-pax only. Of course, we must find a way of summarizing all this in regulatory text as we do not want another table in the EN. There is a proposal at the end of this document. 5.2) As a preliminary simplifying step we have found that, unlike part B-1, it appears that none of the regulations in part B-2 apply to cargo ships carrying liquids (e.g. tankers, IBC, IGC) so we could define the term “dry cargo ship” for use throughout part B-2. For example the title of Reg. 9 could become “Double bottoms in passenger ships and dry cargo ships” instead of “Double bottoms in passenger ships and cargo ships other than tankers.” 5.3) Often, the applicability is clear from the title or the wording of individual regulations but in Reg. 12, for example, it is not specified in the title. The sources of the regulations in S90 comprise a mixture of those for cargo and passenger ships and this is reflected in the text of the regulations in S2009 where there are many references to “bulkhead deck” but only one to “freeboard deck” (Reg. 12.8). Is there a danger that Reg. 12.1, for example, could be thought to apply exclusively to passenger ships because it only refers to a “bulkhead deck”? Perhaps this problem is covered by the definition of bulkhead deck in Reg. 2.19? Or should it be made clearer in the text of the regulations or the title as, for example, in regulation 15 where there are frequent references to “the bulkhead deck of passenger ships and the freeboard deck of cargo ships”? One way of addressing this issue is indicated in the proposal at the end of this document. 5.4) Another key point to consider for dry cargo ships in part B-2 is to what degree the smaller ones (L < 80 m) should be subject to damage stability analysis. Many of the regulations define subdivision, internal and external water-tightness etc in prescriptive terms and so are easily applied to all sizes of cargo ship without the need for damage calculations. Several, however, require information only obtainable from some degree of damage stability analysis which in turn involves computer modelling etc. Some typical examples are:-

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5.4.1) Regs. 9.6, 9.7, 9.8 and 9.9 - if it is decided not to fit a DB in certain areas or if the DB height under a long lower hold is less than prescribed, calculation of si is required for such areas to prove that si = 1. 5.4.2) Reg. 13-1.1 – if relaxation of the degree of water-tightness of openings above the freeboard deck is required it must be demonstrated that any progressive flooding can be easily controlled and that the safety of the ship is not impaired. This could only be determined by damage stability analysis. Regs. 13-1 are almost identical to S90 Reg 25-9 which only applied to cargo ships >= 80 m L. 5.4.3) Reg. 15-1.1 – external openings leading to compartments assumed intact in the damage analysis but which lie below the final damage waterline are required to be watertight. Regs. 15-1 are almost identical to S90 Reg 25-10 which only applied to cargo ships >= 80 m L. 5.4.4) Reg. 16.2 – watertight doors shall be tested by water pressure to a head of water they might sustain in a final or intermediate stage of flooding. In S90, reg. 18 required the head to be taken only to the freeboard deck. For S2009 a damage analysis would therefore be needed to determine the depth of immersion of the door. 5.4.5) Reg. 16-1.2 – any vent trunks passing through the bulkhead deck shall be capable of withstanding the water pressure that may be present within the trunk taking into account maximum allowable heel angle during intermediate stages of flooding, in accordance with reg. 7-2. In S90, this only applied to ro-pax ships. In S2009 (current version), calculations for intermediate stages of flooding are only required for passenger ships so does this regulation only apply to pax (including ro-pax) ships? 5.5) A problem arises when mixing deterministic and probabilistic damage stability calculations - for the latter the damage extents to be assumed are not fixed. In reg. 9.8 (5.4.1, above) deterministic extents of damage are specified and “si = 1” is simply being used as a deterministic “pass/fail” criterion. But for 5.4.2 to 5.4.5, if a full probabilistic damage analysis is carried out, a significant number of cases will fail (s=0) so which damage cases are to be used to determine, for example, the head of water in Reg. 16.2? Is it the damage case producing the lowest A or s value? Alternatively, if a deterministic calculation is to be undertaken, what extents of damage are to be used? One way of addressing these questions is indicated in the proposal at the end of this document. 6) There was a statement in SLF 53/WP.6 para. 25:“…..This proposed amendment to regulation II-1/4.1 also clarifies that relevant parts of SOLAS chapter II-1, parts B-1 through B-4, also apply to cargo ships of less than 80 m of length, including double bottom arrangements”. In fact, as shown in the new text agreed at SLF 53 (above), the agreed amendment to reg. 4.1 only specified the applicability of B-1. It is important that the applicability of B-2 to B-4 is clarified elsewhere. 7) Also of note are the statements in SLF 53/19 para. 14.6 (SLF Report to MSC):“The Sub-Committee also supported the applicability of double bottom requirements to all SOLAS ships without any length restrictions and the development of probabilistic bottom damage stability requirements, following a goal-based approach.” And the ToR under 14.10.2:“consider the validity of applying paragraph 8 pf SOLAS Reg. II-1/9 to smaller ships and, if necessary, suggest appropriate amendments.”

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The “development of probabilistic bottom damage stability requirements” refers, we believe, to the work of GOALDS and cannot be fully addressed until their findings are reported to us. 8) In the light of 6) and 7) we will discuss the validity of applying Reg. 9.8 to smaller cargo ships in conjunction with your responses to the Round 4 questionnaire (see item 13.1 below). 9)

Part B-3 is clearly applicable only to passenger ships (specified in the title).

10) Some of Part B-4 applies to passenger ships, some to cargo ships and some to roro passenger ships. Just as for part B-2, the applicability of each regulation within part B4 is usually defined either within the regulation itself or in its title as follows:10.1) Regulation 19 – Damage control information – we suggest that the application of regs. 19.1 – 19.5 should be as follows (assuming “dry” cargo ships excludes bulk liquid carriers – see 5.2 above):19.1 19.3 and 19.4 – all passenger ships and dry cargo ships of 24 m L and upwards and 500 GT and upwards. 19.2 – all passenger ships only (as specified in text). 19.5 – all passenger ships and dry cargo ships of 80 m L and upwards. It is suggested that the intent of Reg. 19.5 is that damage control information should be supplied to passenger ships of all sizes but only to cargo ships of length 80 m and upwards to which the damage stability requirements of Part B-1 apply. This would exclude all cargo ships complying with the subdivision and damage stability regulations in other instruments (which have their own requirements). 10.2) Regulation 20 – Loading of [Passenger] Ships – it had been unanimously agreed by the CG in 2010 to remove the word “Passenger” from the title (see Q53) but this was not accepted in plenary at SLF 53 (ref. SLF 53/WP.6 para. 21) and the decision was deferred for further consideration by the CG. It will hopefully be resolved in Round 6 (see new discussion for Q53D below). If we finally agree to remove the word “passenger” from the title then we will need to specify which cargo ships the regulation applies to. It is suggested that easiest way to do this is, in Part B-1 reg. 4.1, to specify the general applicability of Parts B-2 and B-4 to passenger ships of all sizes and dry cargo ships (defined as proposed in 5.2 above) “except where expressly provided otherwise” (US proposal). We could then define “small dry cargo ships” as those with L between 24 and 80m but with gross tonnage greater than or equal to 500 tons (based on Part A reg. 3(a)(ii)). This is discussed further under 11) below. If there is no express provision in any title or regulation, the “default applicability” in Part B-2 and B-4 is “passenger ships of all sizes and dry cargo ships” (implying all “SOLAS” sizes but excluding tankers etc). One way of addressing these questions is indicated in the proposal at the end of this document. For information, note that Reg. 20.1 is taken directly from SOLAS90 Part B Reg. 8.7.4; Regs. 20.2 & 20.3 are from SOLAS90 Part B Reg. 9.1 and 9.2. All of these SOLAS90 regulations applied exclusively to passenger ships and there appears to be no equivalent provision in Part B-1 of SOLAS90 (cargo ships). If we do decide to keep “passenger” in the title we could perhaps rely on the IS 2008 Code to cover these provisions for cargo ships.

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10.3) Regulation 21 – Periodical operation and inspection of watertight doors, etc., in passenger ships – clearly applies only to passenger ships. 10.4) Regulation 22 – Prevention and control of water ingress, etc – you may recall that a proposal to add [“in passenger and cargo ships”] to the title was not accepted in plenary at SLF 53 (see Q56). The regulations clearly apply to both types and are largely derived from both SOLAS90 Reg. 15 (applicable to passenger ships) and Reg. 25-9 (cargo ships). The new “default applicability” could therefore apply here without the need for amending the title (see proposal at the end of this document). 10.4.1) Freeboard Deck / Bulkhead Deck. Reg. 2.1918 implies that the terms “freeboard deck” and “bulkhead deck” are interchangeable. Our comment on this is that if this regulation applies to both types the words “bulkhead deck” should perhaps be replaced by “bulkhead deck in passenger ships or freeboard deck in cargo ships”. This may result in the wording becoming rather clumsy. Alternatively an EN could be added – “the term ‘bulkhead deck’ in this regulation should be taken to mean ‘freeboard deck’ in cargo ships”. Alternatively, the application of each individual regulation may be understood in context e.g. Reg. 22.1 cross-refers to regulation 13.10 (which only applies to passenger ships). Can we therefore assume Reg. 22.1 only applies to passenger ships? Maybe use of “bulkhead deck” is deliberately used to indicate applicability to passenger ships only but the term “freeboard deck” never appears in this regulation so it is more likely that all the sub-paragraphs apply to both types of vessel? This is all a little confusing – but we have tried the method of repeatedly used “bulkhead deck in passenger ships or freeboard deck in cargo ships” in the proposal at the end of this document. Your comments are invited in Q6D, below. 10.5) Regulations 23 – 25 The application of the remaining regulations in Part B-4 is easily seen in the titles or in the regulations themselves (e.g. Reg. 25.2). The title of reg. 24 may change slightly (see Q56, below) if the USA proposal is accepted:[Additional requirements measures for the] prevention and control of water ingress, etc., in cargo ships. 11) There is some uncertainty over the lower size limit for cargo ships. Chapter I Part A, Reg. 3 (a) (ii) states that the present regulations unless expressly provided otherwise do not apply to cargo ships of less than 500 gross tonnage. Also Part A Reg. 1(a) states that “Unless expressly provided otherwise, the present regulations apply only to ships engaged on international voyages.” The IS 2008 Code and SOLAS Part B-1 Reg. 5.1 only apply to cargo ships of length 24 m and upwards. It would seem that we should only apply the relevant parts of SOLAS to cargo ships of more than 500 gross tons AND 24 m L and upwards (or as expressly defined in each chapter)? That is, no cargo ship of less than 24 m in length but greater than 500 gross tons would need to comply with SOLAS Part B nor would a cargo ship of less than 500 tons but more than 24 m L. Do you agree? This distinction between dry cargo ships and “small” dry cargo could either be made in the definitions regulation (2) or at the beginning of revised reg. 4.1 (See Q6D, below). 12) We have made a series of proposals at the end of this document which we hope will cover all the issues above and hopefully satisfy most of your responses to round 4, which we now discuss in more detail.

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13)

Discussion of Round 4 responses to Q6C

13.1) B-2 Applies to cargo vessels with L>24? Seven members were fully in favour. Germany has reservations about Reg. 9 for small ships. Vanuatu was opposed to “one size fits all” , expressing particular concern about applying reg. 9.8 to wide, shallow draught vessels under 80 m L. The US felt that it had already been decided at SLF 53 to apply Part B-2 to all cargo ships irrespective of length. The co-ordinator’s comment 6) above argues that the changes to Reg. 4.1 agreed at SLF 53 only applied to Part B-1 and that the applicability of Parts B2 – B4 still needs to be clarified (i.e the coordinators believe that the statement in WP.6 is not strictly correct). We hope the comments under 7), above, clarify the situation with respect to Reg. 9.8 (i.e. we must await the outcome of GOALDS, where new bottom damage statistics have been uncovered and a new probabilistic bottom damage method is being developed). This also applies to Vanuatu’s comment above. We agree with the US note regarding the origin of regs. 13-1 and 15-1 which we therefore think should only be applied to cargo ships of 80 m and upwards - that is, those subject to probabilistic damage analysis in Part B-1. On the whole, we also agree with the US that SOLAS2009 regs. 9, 10, 11, 12, 15, 16 and 16-1 were applied to all cargo ships (i.e. those >= 500 gross tons and with L = 24 m and upwards) in SOLAS90 although comparison is not always one-to-one. Some of these regulations were introduced into SOLAS90 at the same time as the cargo ship probabilistic regulations were introduced in 1992 (for L >= 100m only) but they relate to more general issues of subdivision and watertightness rather than probabilistic damage stability so we would agree with the US on the applicability. Denmark points out that the SOLAS90 DB requirements for cargo ships first appeared in old Reg. 12-1 in 1992, (at the same time as the cargo ship probabilistic regulations) but accept that they applied to all cargo ships. Denmark’s concern, echoing that of France and Germany, arises when reg. 9.8 is applied to smaller cargo ships, for which they feel it may be too onerous. This raises the question, which is the subject of the ToR:“consider the validity of applying paragraph 8 pf SOLAS Reg. II-1/9 to smaller ships and, if necessary, suggest appropriate amendments.” Given that Reg. 9.8 may eventually be replaced by a new probabilistic regulation, this may be some time off yet, depending on the timetable of the GOALDS project. For now there seem to be at least two possibilities for “relaxing” the regulation:a) Reduce s from 1 to some lesser number, such as [0.9] or [0.5] or b) Re-introduce some “flexibility”, as suggested by Vanuatu. For b) the basic requirements for double bottoms in cargo ships in Regs. 9.1 to 9.4 are taken from SOLAS90 Reg. 12-1. The co-ordinators once thought that the concerns expressed by some delegates over fitting a double bottom in cargo ships under 80 m L could be addressed by using the “escape clause” in Reg. 9.1, which states “as far as this is practicable”. This was quite clearly the case in SOLAS90 (reg. 12-1.1) – but it used to lead to disputes over what standard to apply if a double bottom was not fitted for reasons of “impracticality”. The difficulty of fitting double bottoms in smaller passenger ships was also recognised in SOLAS90 Reg. 12.1.1 where, for example, ships between 50 and 61 metres in length did not need to fit a double in the engine room. We also note that under SOLAS90 the requirements for DB’s in cargo ships only applied to ships constructed on or after 1st February 1992, which is the same date that the probabilistic cargo ships came into force for ships with L >= 100m

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However, it is quite clear that in its present form SOLAS 2009 reg. 9.6 permits no flexibility – either a double bottom is fitted or s must equal 1 following bottom damage to areas not fitted with a double bottom. This must have been the intention when the regulations were written. This leaves option a) - a reduction in “s” or not applying regs. 9.6, 9.7 and 9.8 to “small” cargo ships at all. This will be put to you in the questionnaire together with a request for alternative ideas (See Q6D, below). RINA’s clarifying comments on the possible length/tonnage conflict are noted – we hope that 11), above answers this concern. We note with interest their comment that the class rules only require a double bottom to be fitted in cargo ships > 500 ton gross which would support the case of those in favour of fitting double bottoms in smaller cargo ships of < 80 m L. Regarding DE – we would not have time to consult with them if we are to meet our current completion date of SLF54 but we can discuss this option further in the WG at SLF 54 if a time extension to this agenda item is agreed to. 13.2) B-2 only applies to cargo vessels with L>80? Two members fully agree. However, we tend to agree with RINA that we cannot say in general that all the regulations in B-2 apply exclusively to cargo ship of L = 80 metres and upwards as several provisions, such as collision bulkheads (Reg. 12), should be applied to smaller vessels (see item 13.1 above). In general we would argue that the L = 80 and above limit will apply to any regulations involving probabilistic damage stability calculations in Part B-1 either directly or indirectly (including in the latter category Reg. 13-1 and 15-1, as explained in item 13.1 above). Using this principle we would not necessarily agree with Spain that regs. 9.7 and 9.8 should only apply to L = 80 and upwards. Although si, as used in Reg. 9.8, is a probabilistic term it is only being used here as a deterministic criterion for controlling the subdivision of the DB and not as part of a full probabilistic analysis. This also applies, we suggest, to Japan’s argument. We feel that the calculation of si for bottom damages is completely separate from the full side damage stability analysis in Part B-1. However, there is the issue of modelling the ship for damage analysis (see 5.4.1 above). Your opinions are therefore sought in Q6D, (below). 13.3) Where should we clarify which cargo vessels must comply with B-2? The US, RINA and Germany all favour Reg. 4. Denmark says it should be in SOLAS, not the EN (as does Germany). Italy prefers the regulation title; the US would accept this as a second choice with detailed applicability in the regulations (EN should not be necessary). UK prefers direct references in the main regulation text. As discussed above, it may be necessary to use all the above options due to the complexity of the applicability, with some additional clarification of the titles – see new proposal below. 14) New Proposal Below is a proposal which we hope will clarify as many issues as possible without the use of footnotes or EN and also incorporating parts of the Annex to MSC 89/22/8. The highlighting colour code is as follows:Q6 SOLAS Consolidated Edition 2009; Resolution MSC.281(85); SOLAS Consolidated Edition 2009; Agreed EN Text Changes SOLAS Consolidated Edition 2009; Resolution MSC.281(85);

Original question numbers Regulation text still under discussion EN text still under discussion Changes to SOLAS agreed up to Round 4 Changes to EN text agreed up to Round 4 Text changes proposed in Round 6 EN changes proposed in Round 6

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The proposal relies on the applicability of Part B-1 being specified in regulation 4.1 with a text similar to that agreed at SLF 53 but eliminating the footnote (to conform with MSC 89/22/8) and the table in the EN. To simplify the text further, we propose to define the term “small dry cargo ship” in reg. 4.1 as being a cargo ship with 24 760 mm and to allow for L > 100m. This would satisfy Spain’s objection to combining the two sets of regulations for vessels with L > 80 as proposed in the UK paper. Q8B (for SLF53 S-C and WG). If the S-C agrees to extend the deadline for considering footnote .4 (ref. SLF 53/12 para. 25.2) , do you think that we should then concentrate on improving the safety level of all OSV’s with L>24 m to account for deeper penetration damages by amending MSC.235 only or by combining MSC.235 (amended as appropriate) with S2009 Part B-1, as proposed by the UK in MSC 85/23/1 paragraph 2.6?

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Amend MSC.235 only?

France (added in round 4 questionnaire).

Combine Part B-1 with MSC.235 (amended as necessary)? Comments? This issue was discussed at SLF 53 and it was agreed to wait for the results of further research on the equivalence of MSC.235 and SOLAS 2009 Part B-1 as applied to OSV’s. TOR .1 and .2 for SLF 54 Agenda Item 7 (Cargo Ship Subdivision) now refer. Note for Round 4 questionnaire:- No questions or comments are needed at this stage – we will deal with this item under SLF 54 AI 7 and in the meantime await the results of any research being carried out.

Q8. FOR SLF54: See SDS CG report SLF 54/7 on the separate agenda item. Also papers SLF 54/7/1 and /INF.2 from US and SLF 53/INF.7 from China. AWAIT OUTCOME OF AI7 BEFORE UPDATING SOLAS R4.1. MEANTIME THE REFERENCE TO THE OSV REGS (A469) CAN BE UPDATED to 2006 (MSC.235(82)). .5 Code of Safety for Special Purpose Ships, 2008 (Resolution MSC.266(84); (Resolution A.534(13)) ; [Coordinator’s Note - this Resolution is still quoted in the S2009 consolidated edition].

R4.1 ftn .5 (Change reference for SPS?) Q9. Should the reference to A.534 be changed to MSC.266(84)? Yes China, Finland, Germany, Japan, MI, Norway, Spain, Denmark, UK, US, Sweden No Comments?:Finland: Special purpose Ships have to fulfil Part B-1. Special reductions in respect of N in reg. 6 Norway: Res. MSC.266(84) was approved before the revised chapter entered into force. Consequently the footnote must refer to revised Code. Round 1 Discussion: Finland and Norway’s comments are noted. No opposing views were received.

CONCLUDED - PROPOSAL ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53 (See SLF 53/14 para 12.2). Accepted at SLF 53

Q9. AT SLF 54, RECOMMEND REFERENCE BE CHANGED AS AGREED AT SLF 53

.6 Damage stability requirements of regulation 27 of the 1966 Load Lines Convention as applied in compliance with resolutions A.320(IX) and A.514(13), provided that in the case of cargo ships to which regulation 27(9) applies, main transverse watertight bulkheads, to be considered effective, are spaced according to paragraph (12)(f) of resolution A.320(IX), except ships intended for the carriage of deck cargo; and

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.7 Damage stability requirements of regulation 27 of the 1988 Load Lines Protocol, except ships intended for the carriage of deck cargo. [Coordinator’s Note - Germany proposed (ref. SLF 52/19 paragraph 14.2) that the inclusion of footnotes .6 and .7 should also be re-considered in the context of the UK paper MSC 85/23/1 (see below) and proposals should be submitted to this CG].

R4.1 ftn .6 and .7; (re-consider?; add MODU Code to list of equivalents to S2009?) Q10. Are there any specific reasons for re-considering footnotes .6 and .7 and/or any new proposals? Should the CG consider this issue separately alongside the UK proposal to remove footnote .4 (see also Q8)? Comments / Proposals?:China: No, footnotes .6 and .7 should be kept. Finland: Removal of footnotes .6 and .7 should be considered by the CG. Japan: Does not support re-opening this issue. MI: Retain footnotes 6 and 7, no valid reason for deletion submitted for consideration. Norway: These footnotes should be considered separately. It should be noted that these regulations will not generate data suitable for a limit curve in accordance with regulation 5-1.2.1. Spain: We can consider also a revision of these footnotes (.6 and .7). Anyway, we need strong technical reasons to justify the removal of footnotes .6 and .7. We suggest circulating between the working group members the available technical studies in relation to this particular matter. In any case, we suggest considering these footnotes separately, the design and configuration of the vessels affected by footnotes .6 and .7 is very different than the affected by footnote .4. This matter should be further studied. Denmark: No. US: Although we are not opposed to re-considering the validity of these footnotes, we think this should be done separately from footnote .4. It would be useful to know the specific concerns associated with footnotes .6 and .7. Sweden: Does not have any specific reasons to re-consider the footnotes. Round 1 Discussion: We believe the suggestion for updating some of the remaining footnotes, specifically .6. and .7, originally came from paragraphs 2.7 to 2.9 in the UK paper MSC 85/23/1 (quoted below for easy reference), supported by Germany at SLF 52. We apologize for not making this clearer in Round 1:2.7 A further consideration of significance is that the footnotes to regulation 4 refer to “regulations” meaning IMO instruments, but only .6 and .7 refer to specific regulation numbers. This may be a reflection of the fact that whilst ICLL applies to virtually all SOLAS ships, regulation 27 is merely an option within it. However it may be argued that, for example, (footnote) .5 is only available to ships which comply fully with all Special Purpose Ship provisions. It may also be noted that these equivalences are related to SOLAS part B-1 which includes standards for openings in watertight divisions (regulations 25-9 and 25-10 in the soon to be superseded version). The new part B-1 does not contain such regulations, which have been moved to part B-2 and therefore will no longer be part of the equivalence. 2.8

Noting 2.7 above, it might be considered appropriate to include the MODU Code in the list

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of regulations deemed to confer equivalence to part B-1. Scope of the proposal 3 To consider the footnotes to regulation 4 of part B of chapter II-1, as adopted by resolution MSC.216(82). To consider deleting footnote .4, and to update references to the remaining footnotes as necessary. This will potentially widen the application of part B-1, for certain ship types. We have already agreed under Q7 above to clarify the heading of the footnote by adding the words “the damage stability regulations in”. We could further clarify it by adding “instruments and” between “following” and “regulations” to read:“Cargo ships shown to comply with the following [instruments and] regulations may be excluded from the application of [the damage stability regulations] in part B-1”. Alternatively it may have been the intention only to reference the equivalence to the damage stability regulations within the various instruments, in which case we could change the wording to:“Cargo ships shown to comply with the [damage stability regulations within] the following [regulations] may be excluded from the application of [the damage stability regulations] in part B-1”. This would still leave open the question of whether or note to include the MODU Code in the list of instruments which are deemed to confer equivalence to part B-1. Q10A. Most members in answering Round 1 expressed little enthusiasm for changing the remaining footnotes as proposed in MSC 85/23/1. Is this still the case in the light of the above discussion or do you think some clarifying changes may be needed as proposed, including the addition of the MODU Code to the list? Yes, Finland, US, Japan, RINA, France (with comment), UK, Denmark changes needed No changes

MI, China, Norway, Sweden

Comments / Alternative Proposals / MODU Code?:MI: Remain of the opinion that the matter of equivalence should be considered as a separate issue. US: We support adding the MODU Code to the list. We also support the following proposed change: “Cargo ships shown to comply with the following [instruments and] regulations may be excluded from the application of [the damage stability regulations] in part B-1”. Japan: Japan does not have a strong position. RINA: As regulation 4 already includes the statement “.....comply with subdivision and damage stability regulations in other instruments”, we would propose that the footnote should be amended as follows: “Cargo ships shown to comply with the following subdivision and damage stability regulations in other instruments may be excluded from the application of Part B-1”. France: Ships covered by MODU code cannot be treated by SOLAS 2009, so MODU code should be added to the list. CLIA: Not directly relevant to CLIA. Round 2 Discussion: For a full discussion of the issues relating to footnotes .6 and .7 and the addition of the MODU Code to the list of instruments considered to provide equivalence to S2009

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Part B-1 see the CG report to SLF 53 (SLF 53/12 paragraph 24). In order to improve the clarity of the opening part of the footnote to regulation 4.1 in accordance with comments made under paragraph 2.7 of the UK paper MSC 85/23/1 we would like to propose that the S-C consider adopting one of the four alternative texts below, bearing in mind that the CG has already agreed to change the sentence as underlined (see Q7):“* Cargo ships shown to comply with the following regulations may be excluded from the application of the damage stability regulations in part B-1:” Alternative 1: “Cargo ships shown to comply with the following [instruments and] regulations may be excluded from the application of [the damage stability regulations] in part B-1”. Alternative 2: “Cargo ships shown to comply with the [damage stability regulations within] the following [regulations] may be excluded from the application of [the damage stability regulations] in part B-1”. Alternative 3: “Cargo ships shown to comply with the following [subdivision and damage stability] regulations [in other instruments] may be excluded from the application of [the damage stability regulations] in Part B-1”. Alternative 4 (see Q6 for background): “The following instruments and regulations contain stability requirements for cargo ships”:In addition, there is some support within the CG for adding the MODU Code to the list of instruments deemed to provide equivalence to Part B-1. This could be added as footnote .8. Q10B (for SLF53 S-C and WG). Please state which of the above 4 alternatives you prefer to clarify the opening sentence of the footnote to regulation 4.1. (or propose another). Also please state whether you think that the MODU Code should be added to the list of instruments in the footnote. (Ref. SLF 53/12 para. 24). Prefer Alt 1 Alt 2 Alt 3 Alt 4 Other proposal?

Co-ordinator’s Note after round 4 responses: Denmark included the following alternative in the R4 questionnaire: “Cargo ships shown to comply with the subdivision and damage stability requirements of the following instruments and regulations may be excluded from the application of the damage stability regulations in Part B-1”.

Add MODU Code?

Comments?:- Alternative 4 (“The following instruments and regulations contain stability requirements for cargo ships”) was finally accepted by WG3 at SLF 53 and will be used in conjunction with the agreed revised text for regulation 4.1 (see Q6B). However, Germany is to submit a paper to MSC 89 on the legal status of the footnotes in general as it was felt that such important text should preferably form part of the regulation. So it is possible that regulation 4.1 may need to be looked at again after MSC 89. As we recall, the group was divided on the inclusion of the MODU Code on the list of cargo ships not needing to comply with SOLAS Ch II-1

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Part B-1. Also there was not unanimous support for deleting the Table in the EN for Regulation 4.1 (see below) as some felt it was still useful. Therefore the issue of the footnotes, MODU Code and the EN Table will be re-opened for discussion in the CG before SLF 54.

Q10C (for Round 4 Questionnaire). If we set aside the question of further changes to the footnote/regulation and inclusion of the table in the EN (see also Q6C), until we hear from MSC 89 in May 2011 (ref paper MSC 89/22/8), could we in the meantime again ask for your opinion on whether the MODU Code should be added to the list of regulations/instruments deemed to be equivalent to SOLAS 2009 Part B-1 in the footnote to Reg. 4.1? We may have to accept a majority vote. Add Yes: Vanuatu, US, Finland, Italy, UK, France, MI (remain of the opinion that MODU the MODU Code should be added to the list), Spain Code? No: Norway, RINA, Denmark (with comments), Germany Comments?:Vanuatu: Please see our previous comment on absolutism; the geometry (and various design constraints) of MODUs, whether semi-submersible or jack-up do not lend themselves to readily accept deep sea vessel definitions with respect to rule application(s). US: For MODUs, we believe the IMO MODU Code provides an “appropriate alternative standard” and should be accepted in this context. We do not think this item should be viewed in terms of strict “equivalency”. RINA: With respect to stability issues the MODU Code is a standalone document, with no reference to the SOLAS Convention. This also the case with the HSC 2000 Code. It is considered that if a reference should be made to the SOLAS stability requirements then this should be made from the MODU Code to the applicable SOLAS regulations. Denmark: The MODU Code damage stability standard is not equivalent to SOLAS Part B-1 as it only includes limited damage penetration. Italy: MSC89 OUTCOME: Application of SOLAS subdivision standards to cargo ships. 22.32 The Committee considered document MSC 89/22/8 (Germany and United Kingdom), proposing to develop amendments to SOLAS regulation II-1/4 in order to clarify the application of SOLAS subdivision standards to cargo ships which are complying with the subdivision standards of other IMO instruments, and agreed to include, in the 2012-2013 biennial agenda of the SLF Sub-Committee and the provisional agenda for SLF 54, a planned output on "Development of amendments to SOLAS regulation II-1/4 concerning subdivision standards for cargo ships", with a target completion year of 2013. Coordinators’ Note: Thanks for latest update from MSC, Italy.

Round 6 Discussion: As we are in the process of removing the footnote to Reg. 4.1 and the table in the EN (see Q6 above) we now only need to decide whether the MODU Code should be added to the list of regulations in revised reg. 4.1.2 and 4.1.3. There is a majority of 8 to 4 in favour of adding the MODU Code to the list so our inclination is to accept the majority verdict and propose this change to the SLF sub-committee. We hear the counter arguments from Denmark and RINA but we feel that the MODU Code is a highly specialized set of regulations subject to continuous scrutiny at IMO (we are now in the third re-issue (2009)) and that if there are any deficiencies in the damage stability content (as Denmark states) these would be better addressed within the Code rather than replacing the damage stability section with S2009; a similar argument would apply to RINA’s comments. We remember in the SLF 53 WG that concern was expressed by some members that if we put the MODU Code on the list certain owners might try to classify their vessels as MODU’s in order to avoid complying with SOLAS2009 (for example to avoid fitting a DB). However, we feel that it is the responsibility of each Administration to adjudicate, based on the clear and specific definition in the MODU Code:1.3.40. Mobile offshore drilling unit (MODU) or unit is a vessel capable of engaging in drilling operations for the exploration for or exploitation of resources beneath the seabed such as liquid or gaseous hydrocarbons,

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sulphur or salt.

CONCLUDED PROPOSAL TO ADD “MODU CODE” TO PROPOSED NEW REGULATIONS 4.1.2 AND 4.1.3 ACCEPTED BY CG ON A MAJORITY VERDICT.

AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 54. Are there any further comments / objections to this decision? Poland: I support to add MODU CODE to proposed new regulations. US: Fully agree with this conclusion. China: No comments. Q10. AT SLF 54 - RECOMMEND THAT MODU CODE BE ADDED TO THE LIST OF REGULATIONS DEEMED EQUIVALENT TO S2009 IN R4.1 [Regulation 4.1 [Coordinator’s Note, for the future of this EN and table see Q6D & Q10] Cargo ships complying with the subdivision and damage stability regulations of other IMO instruments listed in the footnote are not required to comply with part B-1, regulations 6, 7, 7-1, 7-2 and 7-3 but must comply with the regulations indicated in the table below. Regulation Applies Part B-1 5 5-1

X X Part B-2

9

X(1)

10

X

11 12

X X

13-1 15

X X

15-1

X

16 16-1

X X Part B-4

(1) (2)

19

X

22 24 25

X X X(2)

Only applies to cargo ships other than tankers. Only applies to single hold cargo ships other than bulk carriers. ]

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Regulation 4.1 (ref. SLF 52/17/6 - Norway) Include regulation 20 in the table listing applicable regulations found under Regulation 4.1 in the EN. [Co-ordinator’s Note:- changes to Reg. 4.1 are to be the subject of a new Agenda Item (13) at SLF 54, completion 2013, so we may pass on any deliberations via a paper to IMO.] Q11. Do you agree that Reg. 20 (loading of [passenger] ships) should be added to the above table in the EN, as proposed? Yes

China, Finland, Germany, Japan, MI, Norway, Italy, Spain (see comments), Denmark, UK, US, Sweden

No Comments?:Finland: Title to be changed. “Passenger” to be removed. CLIA: ? Not clear what this is doing. Italy: Agreed, but the title should be changed removing the word “passenger” in square bracket. Spain: To be considered in combination with Q53. To include this reference in this table, the term ‘passenger ship’ should be deleted. In any case, in our opinion, from stability purposes, the relevant regulation to be included in the table is only 20.1, not 20.2. Explanatory note: Regulation 20.2 is related to pollution (segregation of oil and water ballast). All ‘SOLAS’ cargo ships (more than 500 GT) are covered by MARPOL, Annex I, regulation 16 (including more clear and complete requirements). Not all passenger ships are covered by MARPOL, Annex I, regulation 16, because this regulation applies only to ships with more than 400 GT, and all passenger vessels engaged on international voyages are covered by SOLAS. Denmark: If the title of Reg. 20 regulation is changed to also include cargo ships, we have no objection if the reg. is added to the table in the EN. US: In principle yes, but see our comment on Q6 about deleting the EN table for regulation 4.1. Round 1 Discussion: Although we have almost unanimous agreement on this, provided the heading of Regulation 20 is changed to “Loading of Ships”, Spain seems to make a good case for only including Reg 20.1. On the other hand, perhaps a simpler solution would come from the US’ proposal to remove this EN table to the footnote altogether (see Q6A, above). IF we have a large “Yes” vote for Q6A then the US proposal could be accepted and we can delete the table altogether. If not then we could simply add Reg. 20.1 to the list as Spain proposes. Q11A. Given the support for changing the title of Reg. 20 and adding it to the Table, is there nonetheless a preference for either (a) deleting the Table altogether as proposed by the US under Q6 above or (b) only adding Reg. 20.1 to the Table as proposed by Spain? Delete MI, US, Japan, Sweden Table? Keep Germany, Finland, Italy, RINA (with comments), France (with comments), Table + Norway (with comments), CLIA, Denmark 20.1 only? Further Thoughts / Comments?:MI: Agree deletion.

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China: No comments. RINA: We would concur with the proposal to amend the title of regulation 20 to cover both cargo and passenger ships and that the explanatory note for regulation 4.1 is included in the EN. France: Considering the uncertainty on reg 5, 5-1 and 9, it seems more clear to keep the table. Norway: Support Spain. This provision in 20.2 was introduced already in SOLAS-60 and was probably intended as a safety measure in passenger ships to prevent machinery malfunctions rather than as a pollution concern. See also answer to Q6A. Round 2 Discussion: We have proposed a completely new text for reg. 4.1 which should enable the EN table to be deleted meaning that we can no longer add reg 20 (or 20.1) to it. However, if we agree to delete the word “passenger” from the heading of reg. 20 this should not be a problem. So we await the outcome of Q6B after discussion at SLF 53. Comments post SLF 53:- Deletion of “passenger” in the title of Regulation 20 was not agreed to in plenary, with objections from ICS & Greece. So the issue of including this regulation (or only 20.1) in the table is still open for discussion by the CG and depends upon whether it is decided to retain the Table in the EN (see comments above under Q10B). (See SLF 53/WP.6 paragraph 21 for details).

Q11C (for Round 4 questionnaire). As it was decided at SLF 53 to retain the word “Passenger” in the title of Reg. 20, this means Reg. 20 (or 20.1) cannot now be added to the Table, which only applies to cargo ships. It is proposed that we take no further action for now until MSC 89 decides on the status of the footnotes in response to the Germany/UK request (ref. MSC 89/22/8) which should then determine whether or not we retain the Table in EN 4.1 etc. Further comments?:Vanuatu: No US: We have no objection to this. However, we take this opportunity to note our view that an important objective of this agenda item is to clarify regulation applicability. When we are finished, there should be no need for any ENs in this regard. Japan: As stated in the previous session, Japan does not support re-opening this issue. China: No comments. RINA: We would concur with the proposal to amend the title of regulation 20 to cover both cargo and passenger ships. In addition we should retain the table, suitably amended to identify the application to cargo ships and passenger ships. This is particularly relevant with respect to the outcome of the question posed in Q6C. France: Agree to the proposal. Spain: OK, support coordinators’ position. Round 6 Discussion: As we are in the process of removing the footnote to Reg. 4.1 and the table in the EN (see Q6 above), we believe that no further action is needed on Q11. The issue of whether or not to remove “passenger” from the title of reg. 20 is discussed in detail under Q6D, above (item 10.2) and Q53D. Q11, NFA AT SLF 54

Regulation 4.1, footnote .1 “OBO ships” means combination carriers as defined in SOLAS regulation II2/3.14 [Coordinator’s Note: This EN should now be deleted from Res MSC.281(85) as the term “OBO” has been removed from footnote .1 in the 2009 Consolidated Edition].

R4.1 footnote .1 Q12. Do you think we need to notify SLF 53 of this change? Yes

China, Germany, Japan, MI, Norway, Italy, Denmark, UK, US, Sweden, France

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No

Finland, CLIA

Comments?:Round 1 Discussion: This item was only introduced as a tidying-up exercise and to act as a flag for future action. There are now 11/2 members in favour of deleting this EN (France also in favour). Q12A. Any further comments at this stage particularly from Finland / CLIA?:China: No comments. Finland: No further comments. France: This will be included in updated version presented at SLF53. Norway: No comment. CLIA: No further comments- Modification acceptable.

CONCLUDED - PROPOSAL ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53. (See SLF 53/14 para 12.3). Deletion agreed at SLF 53

Q12 RECOMMEND EN BE DELETED AS AGREED AT SLF 53

2 The Administration may, for a particular ship or group of ships, accept alternative methodologies if it is satisfied that at least the same degree of safety as represented by these regulations is achieved. Any Administration which allows such alternative methodologies shall communicate to the Organization particulars thereof. 3 Ships shall be as efficiently subdivided as is possible having regard to the nature of the service for which they are intended. The degree of subdivision shall vary with the subdivision length (Ls) of the ship and with the service, in such manner that the highest degree of subdivision corresponds with the ships of greatest subdivision length (Ls), primarily engaged in the carriage of passengers. Regulation 4.3 (ref. SLF 52/3/3 - Germany) [Coordinator’s Note Round 2:- Apologies – the reference should be to SLF 51/3/3] In this paper, Germany proposed that some of the Explanatory Notes should be made mandatory to improve consistency of application and suggested the following paragraph (3bis) be inserted at this point. “The regulations contained in parts B to B-4 should, in order to ensure their uniform application, be applied in conjunction with the Explanatory Notes adopted by the Organization by resolution [MSC …], as may be amended by the Organization, provided that such amendments are adopted, brought into force and take effect in accordance with the provisions of article VIII of the present Convention concerning the amendment procedures applicable to the annex other than chapter 1. A consequential amendment would then be the deletion of the previously considered reference to the draft Explanatory Notes in a footnote to regulation 6.” [Refer to Reg.6 ] The SLF Sub-committee decided to ask MSC 85 to emphasize the importance of the EN but stopped short of suggesting that they be made mandatory. At SLF 51 the German

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delegation reserved its position on the issue with the following statement:“The delegation of Germany stated that they regarded a uniform application of the Explanatory Notes as a crucial prerequisite to implement the safety standard, as defined in the revised SOLAS chapter II-1, uniformly. A respective document, SLF 51/3/3 had been presented to the SLF sub-Committee. This document had been discussed in the group only briefly. The delegation noted that the group had not been willing to follow the German proposal to, firstly, regard the Explanatory Notes as mandatory and, secondly, to identify high-priority specific items to ensure a uniform application of the regulations. Germany reserved its position on the decision of the group and still regarded it as essential for the uniform application of the Explanatory Notes that they should be regarded as an integral part of the new SOLAS chapter II-1. For the delegation of Germany, the issues contained in regulation 4, paragraph 1; regulation 5-1, paragraphs 2, 3 and 4; regulation 7, paragraphs 1 and 2; regulation 7-2, paragraphs 2, 4.1.1, 5.2.1, 5.2.2 and 5.3.1; regulation 7-3, paragraph 2; regulation 9, paragraphs 1,2,6,7,8 and 9; and regulations 15-1, paragraph 1 are particularly sensitive.” [Ref SLF 51/17 para 3.21]. EN (general) Q13. Do you think discussions on the issue of mandatory EN should be reopened? Yes

Germany, Norway, CLIA, Spain, Denmark, UK

No

China, Finland, Japan, MI, Italy, Sweden

Comments?:Finland: Majority at SLF51 was against. If EN become mandatory, the document will have to be revised. Germany: If the EN become mandatory they will have to be revised. May be split in 2 parts (part A Æ mandatory, part B Æ explanations). Norway: While the intent is supported it should be taken into consideration that MSC 85 approved them on the assumption that they were written as voluntary. A new review for the purpose of making them mandatory will probably be a long-term task. Spain: We agree totally with Germany point of view. We also consider that the Explanatory Notes should be regarded as an integral part of the new SOLAS chapter II-1. If the majority of the group decides that only part of the Explanatory Notes is mandatory, we can support (in general terms) German proposal in relation with the more sensitive regulations and paragraphs. We also suggest that the application of the interpretation contained in regulation 6.2.4 (“reduced degree of hazard”) should be mandatory. According the Explanatory Notes, to accept this relaxation, the distance from the nearest land is limited to 20 miles, but, in the past (in relation to the application of A.265 resolution), in some cases, these relaxations were accepted for all ‘short international voyages’. This relaxation affects strongly the required level of safety (R factor), which is, in our opinion the key factor related to S-2009 regulations. Denmark: Either a mandatory EN or an update of SOLAS incorporating the definitions from the EN is needed. US: In our view, it would be more appropriate to consider this issue intersessionally following SLF 53 when the Chapter II-1 revisions are further developed. Sweden: We do not believe that at this time there will be a more constructive discussion regarding this matter. However a uniform application of the regulations is preferred. Round 1 Discussion: The CG is very evenly divided on this issue (6/6) with several suggestions and ideas. This outcome, and our current work on upgrading some of the regulations, suggests that we are not yet in a position to say that we have definitive versions of either the

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regulations or the EN bearing in mind the preamble to MSC.281(85) (Ref. MSC 85/26/Add.1 Annex 22):“Being desirous that definitive Explanatory Notes should be adopted when more experience in the application of the aforementioned subdivision and damage stability regulations and the Interim Explanatory Notes had been gained”. Proposed Action: It is proposed that the responses received to the Round 1 questionnaire be reported to the Sub-Committee with a recommendation that the issue be kept on the agenda for further discussion by the CG after SLF 53, more or less as proposed by the US. Spain obviously has a strong position on the N factor in Regulation 6.2.4 which she may wish to take further with more urgency? Q13A. Do you agree with the action proposed in the discussion above? Yes

MI, Germany, Finland, US, Italy, Japan, RINA (with comment), France (with comment), Norway, CLIA, UK, Sweden, Denmark

No Comments / Alternative Proposals?:MI: Concur. China: No comments. RINA: In practice designers, flag administrations and their RO’s will apply the Explanatory Notes(EN) on a mandatory basis anyhow, so there should be no major impact if the EN were made mandatory sooner rather than later. France: Yes on the principle, but we consider that revision of SOLAS 2009 cannot be done independently from explanatory notes.

CONCLUDED - PROPOSAL TO KEEP ISSUE OPEN ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53. (See SLF 53/14 para 13.3). Comments post SLF 53:-

This item was not specifically raised during SLF 53 to our recollection but will be kept open for SLF 54

Q13C for Round 4 questionnaire. We will keep the issue of mandatory EN open for further discussion at SLF 54. Does anybody have any new thoughts on this subject in the meantime? Comments?:Vanuatu: No US: No comments Japan: It will take a long time to review the whole EN paragraph by paragraph to become EN mandatory, so Japan hesitates to support. China: No comments RINA: In practice designers, flag administrations and their RO’s will apply the Explanatory Notes (EN) on a mandatory basis anyhow, so there should be no major impact if the EN were made mandatory sooner rather than later. Denmark: No further thoughts. Germany: In this context it should be discussed. i) whether EN contain requirements beyond the scope of SOLAS and ii) how legal aspects are to be considered (implementation schedule, legal status, refer to SPS-Code which is also not mandatory) In addition if the EN will be made mandatory, the EN need to be restructured, similar as the IS code in a mandatory part, a part for guidance and supplementary information. This requires a lot of time and work and is outside of the ToR. Finland: No. EC: Preferably EN should be followed, so everybody applies the same rules. However, at the same time it should be considered if a certain degree of flexibility is necessary.

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Spain: We maintain our previous position: part of the Explanatory Notes should be made mandatory. Round 6 Discussion: From your comments we have some points to make:1. Reviewing the EN to decide which should be mandatory is a medium to longterm task and it would not be advisable to start it until the regulations themselves have stabilised. For example there is still considerable work to be done on the roro regulations (Agenda Item 6), and on cargo ship subdivision (AI 7) both of which are due to complete at SLF 55 in January 2013. 2. The SOLAS updates Agenda Item (8) is due to complete at SLF 54, in January 2012 so it is most unlikely that anything useful can be completed in the remaining time but there are good reasons for asking for an extension for another year to harmonize with the completion date of the other agenda items. 3. Germany states that in their opinion, the amount of work involved in dividing the S2009 EN into mandatory and non-mandatory sections would put the issue outside the scope of our own ToR. 4. Our proposal would therefore be that we advise the S-C of your thoughts in our final report with a recommendation that members wishing to pursue the issue of mandatory EN should prepare a case for MSC to adopt it as a new agenda item for consideration in due course by SLF. 5. In the meantime we will concentrate on finalizing the updates and EN in time for SLF 54 (or 55). Q13D (for Round 6 Questionnaire). Do you agree with the proposal outlined in bold in the discussion above (point 4)? Japan, CLIA, RINA, Norway, Germany, Poland, US, Italy, RoK, UK, Y? France, Denmark, China, EC (Yes, but after this task we're on now has been finalized. It may also be good first to gain further experience). Finland N? Comments? Q13 There was a 14-1 majority in favour of proposal 4 (above, in bold) so this was put into the report to the S/C (ref. SLF 54/8/1 paragraph 15.10) for action to be taken as appropriate. 4 Where it is proposed to fit decks, inner skins or longitudinal bulkheads of sufficient tightness to seriously restrict the flow of water, the Administration shall be satisfied that proper consideration is given to beneficial or adverse effects of such structures in the calculations. Regulation 4.4 See Explanatory Notes for regulation 7-2.2, for information and guidance related to these provisions.

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Part B-1 Stability Regulation 5 Intact stability information* 1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion[. and the elements of its stability determined]. [The light ship displacement and the longitudinal, transverse and vertical position of its centre of gravity shall be determined.][Q15] In addition to any other applicable requirements of the present regulations, ships having a length of 24 m and upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part A of the 2008 IS Code. [Co-ordinators Notes:1. The sentence beginning “In addition …” is not contained in the 2009 Consolidated Edition and comes from resolution MSC.269(85) which also deletes the word “information” from the heading. 2. The asterisk (* above) and associated footnote (below) were included in the 2009 Consolidated Edition. CG members may wish to consider whether this footnote and the asterisk should now be removed as the reference to the 2008 IS Code is included in Reg 5.1 itself. See also 5-1.2]. Q14. Will the changes highlighted in yellow to the heading, Reg. 5.1 and footnote be automatically included in the next Consolidated Edition of SOLAS? See also Q19. Yes

China, Finland, Germany, Japan, MI, Norway, CLIA, Italy, Spain, Denmark, UK, US, Sweden

No Comments?:CLIA: No consequence. US: Regarding whether the footnote and asterisk should now be removed; we think they probably should be kept because the regulation is specific to Part A of the 2008 IS Code and the recommendations in Part B should also be used. Round 1 Discussion: This item was simply intended to flag up that action is required to ensure that resolution MSC.269(85) will be incorporated into the next version of SOLAS. The US suggests that the footnote and asterisk should be retained, for the reasons they state (although perhaps the wording of the footnote would have to be changed now that 1st July 2010 is past; also, if we kept the footnote, would we still need the reference to A.749 as well as 2008 IS Code?). Q14A. Do you agree with the US that we should keep the footnote and asterisk and if so, should the footnote refer to both A749 and 2008 IS Code or only to the latter? Yes, keep Germany, Finland, US, RINA, France (with comment), CLIA, UK, footnote+asterisk Sweden, Denmark No, remove MI, Italy, Japan (with comment), Norway footnote+asterisk

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Germany, Finland, France, CLIA only IS2008, US: We think both A749 and 2008 IS Code will need to be included in the footnote because A749 will be applicable to any ships built from 1 Jan 2009 until 1 July 2010. RINA: Supports the US proposal to include both A.749 and the 2008 IS Code Part B. Sweden: A749 and 2008 IS Code. Comments / Further Thoughts?:China: No comments. Japan: Japan thinks that changes highlighted in yellow provide sufficient information. France: 2008 IS Code is equivalent to A749. Additional elements incorporated in 2008 IS Code may be applied to ships constructed before 1st July 2010. Norway: Remove. Since new regulation 2.27 and 5.1 are now in force the footnote and the asterisk would seem redundant. Round 2 Discussion: There is a 9 to 4 majority in favour of keeping the footnote and the asterisk and of those in favour 3 felt that the footnote should still refer to both A749 and the 2008 IS Code as in the 2009 Consolidated Edition. Norway and Japan consider that the footnote and asterisk could be removed; Norway considers that as there is a now a definition for the 2008 IS Code in reg. 2.27 the asterisk and footnote are redundant. The 2 options are shown below to help make the choice:(Alternative 1) Remove asterisk and footnote: Intact stability If “Yes”, do we refer to both A749 and 2008 IS Code or only 2008 IS Code?

1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion and the elements of its stability determined. In addition to any other applicable requirements of the present regulations, ships having a length of 24 m and upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part A of the 2008 IS Code. (Alternative 2) Retain asterisk and footnote: Intact stability* 1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion and the elements of its stability determined. In addition to any other applicable requirements of the present regulations, ships having a length of 24 m and upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part A of the 2008 IS Code.

_______________________ ∗

Refer to the Code on Intact Stability for All Types of Ships covered by IMO Instruments, adopted by the Organization by resolution A.749(18), as amended. From 1 July 2010, the International Code on Intact Stability, 2008, adopted by resolution MSC.267(85), is expected to enter into force.

Q14B (for SLF53 S-C and WG). Do members prefer alternative 1 or alternative 2? Alternative 1? Alternative 2?

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Comments / Further Thoughts / If we keep the footnote should we change “From 1 July 2010, the International Code on Intact Stability, 2008, adopted by resolution MSC.267(85), is expected to enter into force.”

to “On 1 July 2010, the International Code on Intact Stability, 2008, adopted by resolution MSC.267(85), entered into force.” ?

Also would we need to mention that MSC.1/Circ.1292 permitted early application of the 2008 IS Code? Comments post SLF 53:- As these amendments had already been agreed by MSC we have no choice but to adopt them. However it was agreed to change the footnote as highlighted in red below to reflect that 1 July 2010 is now in the past. It was decided not to mention MSC.1/Circ.1292 in the footnote.

Q14. ASK SECRETARIAT TO AMEND FOOTNOTE FOR NEXT ISSUE OF SOLAS

_______________________ ∗

Refer to the Code on Intact Stability for All Types of Ships covered by IMO Instruments, adopted by the Organization by resolution A.749(18), as amended. On From 1 July 2010, the International Code on Intact Stability, 2008, adopted by resolution MSC.267(85), entered is expected to enter into force.

Regulation 5.1 (ref. SLF 52/17/6 - Norway) Many modern ships are built with an unsymmetrical distribution of mass and/or buoyancy in the transverse direction. This could make it difficult for the ship’s master to plan the loading in such a manner that the ship will not have excessive list before proceeding to sea. Bearing In mind the requirements of regulation 5-1, this Administration is of the opinion that the transverse centre of gravity (TCG) should be included in the elements of stability provided to the ship’s master, even if it estimated that this value will be close to zero. Including the amendment previously adopted by resolution MSC.269(85) it is proposed that the paragraph be amended to read: 1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion. The light ship displacement and the longitudinal, transverse and vertical position of its centre of gravity shall be determined. In addition to any other applicable requirements of the present regulations, ships having a length of 24 m and upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part A of the 2008 IS Code. It should be considered whether the Explanatory Notes should include a comment to the effect that a formal inventory of the transverse centre of gravity will only be required when it is to be expected that the TCG will differ significantly from zero due to the ship’s design. Q15. Do you agree to the amendments in square brackets in Reg. 5.1 (and underlined above)? If so should we add a new EN regarding TCG, as proposed by Norway? Yes No

Finland, Germany, Japan, Norway, CLIA, Italy, Spain, Denmark, UK, US, Sweden China

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Comments / Proposals for new EN?:China: TCG of lightweight is not significant in the stability calculation. Spain: In case of a significant unsymmetrical distribution of mass and/or buoyancy in the transverse direction, probably the guidance for the conduct of an inclining test contained in Part B of the 2008 IS Code, and in the internal procedures of the Classification Societies, should be adapted, e.g.: - In the recommended IS Code procedure mean draught (average of port and starboard readings) should be calculated. This mean draught is used in the calculations, assuming the ship upright. - The plotted line obtained from the weight movements (port & starboard) is assumed to be theoretically straight. - Etcetera. In other words, using the recommended and standardized procedure, the transverse position of the lightship could not be obtained in a correct way for a significant unsymmetrical distribution of mass and/or buoyancy in the transverse direction. Denmark: No addition to the EN needed. Lightship TCG should be determined for all vessels. US: Although we don’t necessarily disagree with the impetus of the suggested Explanatory Note (i.e. a formal inventory of the transverse centre of gravity will only be required when it is to be expected that the TCG will differ significantly from zero), such an EN would seem to be contrary to the proposed regulation text. Round 1 Discussion: There is substantial agreement on this issue (11/1), with the exception of China. We would agree with China that in most cases lightweight TCG is not significant but there have been circumstances in which ignoring a non-zero TCG has led to the loss of a ship, which is the basis of Norway’s concern. There is already significant provision made for the determination of TCG in the 2008 IS Code, extracts of which are shown below for easy reference:2.24 A lightweight survey involves taking an audit of all items which should be added, deducted or relocated on the ship at the time of the inclining test so that the observed condition of the ship can be adjusted to the lightship condition. The mass, longitudinal, transverse and vertical location of each item should be accurately determined and recorded. Using this information, the static waterline of the ship at the time of the inclining test as determined from measuring the freeboard or verified draught marks of the ship, the ship‘s hydrostatic data, and the sea water density, the lightship displacement and longitudinal centre of gravity (LCG) can be obtained. The transverse centre of gravity (TCG) may also be determined for mobile offshore drilling units (MODUs) and other ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre mass.

…………….. 4.1.4

Functional requirements

4.1.4.1 The stability instrument should present relevant parameters of each loading condition in order to assist the master in his judgment on whether the ship is loaded within the approved limits. The following parameters should be presented for a given loading condition: .1

detailed deadweight data items including centre of gravity and free surfaces, if applicable;

.2

trim; list;

.3

draught at the draught marks and perpendiculars;

.4

summary of loading condition displacement; VCG; LCG, TCG; VCB, LCB, TCB, LCF, GM and GML;

.5

table showing the righting lever versus heeling angle including trim and draught;

.6

down-flooding angle and corresponding down-flooding opening; and

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.7

compliance with stability criteria: Listings of all calculated stability criteria, the limit values, the obtained values and the conclusions (criteria fulfilled or not fulfilled).

Spain may have a valid point in suggesting that the 2008 IS Code Inclining Experiment procedure should be amended to indicate how the lightship TCG is to be calculated for ships with asymmetry etc. Such changes as may be necessary to the 2008 IS Code will presumably have to be made by the IS WG/CG? Also provision would be needed in the trim and stability book (and computer software) for showing TCG and Transverse Moment. The US point is also valid – the proposed regulation amendment states that TCG shall always be determined whereas the proposed EN implies that this is not always necessary. One could also imagine questions as to the threshold value at which the TCG “differs significantly from zero”. Proposed Action: To try to overcome these problems given the broad agreement on emphasizing the importance of including TCG in the intact stability information for certain ship types and acknowledging that the 2008 IS Code already makes some provision for this, could we propose inserting the following sentence into Reg. 5.1 with no change to the EN?:1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion and the elements of its stability determined. [These shall include the light ship displacement, LCG, VCG and, at the discretion of the Administration, TCG for ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre mass]. In addition to any other applicable requirements of the present regulations, ships having a length of 24 m and upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part A of the 2008 IS Code. Q15A. Do you agree with the additional sentence in square brackets in the proposed action in the discussion, above, being inserted into Reg. 5.1? Yes MI, Germany (with comment), Finland, Italy, Japan, RINA (with comment), Norway (but with comment), CLIA (but with comment), UK, Sweden, Denmark No France (with comment) Comments / Alternatives?:Germany: We would prefer when such wording is incorporated to the IS2008 Code. China: No comments. US: Given the generally limited need to formally determine the TCG (and the difficulty of establishing a threshold; i.e. the proposed “at the discretion of the Administration”), an alternative could be to only address this issue in the EN. Possible EN text could be: “The elements of stability include light ship displacement and the longitudinal and vertical position of the centre of gravity. In addition, the transverse centre of gravity should be determined for ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre mass.”

RINA: Supports the proposed action with the text “at the discretion of the administration” deleted. Where there is an unsymmetrical distribution of mass around the longitudinal centreline then this will be identified at the inclining test. The correction of the TCG to equal zero may be achieved by permanent or variable ballast. France: The only way to verify that TCG is not significantly different from zero is to measure it, so we prefer the previous wording (The light ship displacement and the longitudinal,

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transverse and vertical position of its centre of gravity shall be determined). Anyway, even if light ship is symmetrical, loading condition during the weighing test may not be symmetrical. This should result from a standard weighing and inclining test procedure, and it would be preferable to amend the IS Code accordingly. Norway: Prefer the original proposal in SLF 52/17/6. However, if there is a strong position for the new proposal in square brackets, this could be supported. CLIA: But the previously proposed text, simply requiring TCG to be determined, was sufficient. Round 2 Discussion: Although 11 to 1 members supported the amendment proposed by the co-ordinators the comments indicate that other alternatives may be preferred. These alternatives are therefore presented below for consideration at SLF 53:Alternative 1 (Norway’s original proposal): 1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion [and the elements of its stability determined]. The light ship displacement and the longitudinal, transverse and vertical position of its centre of gravity shall be determined. Norway also suggested that “the EN should include a comment to the effect that a formal inventory of the transverse centre of gravity will only be required when it is to be expected that the TCG will differ significantly from zero due to the ship’s design”. Alternative 2 (Co-ordinator’s proposal in Round 1 discussion (mostly taken from definition 2.24 in the IS 2008 Code): 1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and upwards, shall be inclined upon its completion and the elements of its stability determined. [These shall include the light ship displacement, LCG, VCG and, at the discretion of the Administration, TCG for ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre mass]. RINA suggests removing “at the discretion of the Administration”. Alternative 3 (USA’s proposal): Keep the regulation unchanged but add the following EN:“The elements of stability include light ship displacement and the longitudinal and vertical position of the centre of gravity. In addition, the transverse centre of gravity should be determined for ships which are asymmetrical about the centreline or whose internal arrangement or outfitting is such that an inherent list may develop from off-centre mass.”

Alternative 4 (Germany): Leave determination of lightship TCG to the 2008 IS Code. France suggests the 2008 IS Code inclining test procedure may need to be amended for TCG. Q15B (for SLF53 S-C and WG). Which alternative is preferred? Alternative 1? Alternative 2? Alternative 3? Alternative 4? Comments / Further Alternatives?:Comments post SLF 53:- In the end Norway’s original proposal (Alternative 1) was accepted without any additional EN.

Q15. AGREED AT SLF 53: RECOMMEND ACCEPTANCE AT SLF 54

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2 The Administration may allow the inclining test of an individual cargo ship to be dispensed with provided basic stability data are available from the inclining test of a sister ship and it is shown to the satisfaction of the Administration that reliable stability information for the exempted ship can be obtained from such basic data, as required by regulation 5-1. A weight survey shall be carried out upon completion and the ship shall be inclined whenever in comparison with the data derived from the sister ship, a deviation from the lightship displacement exceeding 1% for ships of 160 m or more in length and 2% for ships of 50 m or less in length and as determined by linear interpolation for intermediate lengths or a deviation from the lightship longitudinal centre of gravity exceeding 0.5% of Ls L is found. Regulation 5.2 (ref. SLF 52/17/6 - Norway) Replace Ls with load line length (L) for consistency (see Regulation 2.9 and 2.13 for details). R5 (Inconsistency between L and Ls; possible removal of footnote) Q16. Do you agree that L should replace Ls? Yes

Japan, MI, Norway, Spain (see comments), Denmark, UK, US, Sweden

No

China, Finland, Italy

Comments?:Germany: A uniform, comprehensive approach shall be taken. Spain: We consider very urgent to find a solution to this matter. As an additional information, in relation to this tolerance (0,5%L): -

SOLAS II-1 regulation 5.2 makes reference to Ls. Previous Chapter II-1 (regulation 22) makes reference to L. MSC/Circ.1158 makes reference to LBP. IACS UI SC155 (last revision Feb 2008) makes reference to MSC/Circ.1158 tolerances. 2008 IS Code difference between ships subject to SOLAS, and ships not subject to SOLAS (“For the purpose of paragraphs 8.1.2 and 8.1.5 the length (L) means the subdivision length (LS) as defined in regulation II-1/2.1 of the 1974 SOLAS Convention, as amended. For ships to which the Convention applies, and for other ships the length (L) means the length of ship as defined in 2.12 of the Purpose and Definitions of this Code”).

This SOLAS regulation applies to new and existing vessels, for an existing vessel the Ls length should be calculated (Ls was only defined for cargo vessel subject to ‘old’ regulation 25-2). For a vessel (new or existing) not subject to any damage stability requirements, but subject to this regulation, it makes no sense to calculate Ls length. To avoid confusion between Administrations, designers, shipyard, and classification societies, we totally support the proposal of using the length L, unifying the different existing references in different IMO instruments. Round 1 Discussion: There is good support for the proposal to replace Ls with L (8/3) with Spain giving excellent examples of the general lack of consistency but 3 members oppose it and 2 have not indicated a preference. However, the coordinators now believe that we should be very wary of replacing Ls with L because Reg. 5.2 is quite similar in wording to the 2008 IS Code Ch 8.1.2 for which, as pointed out by Spain, there is a footnote (35) stating:-

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“For the purpose of paragraphs 8.1.2 and 8.1.5 the length (L) means the subdivision length (Ls) as defined in regulation II-1/2.1 of the 1974 SOLAS Convention, as amended. For ships to which the Convention applies, and for other ships, the length (L) means the length of ship as defined in 2.12 of the Purpose and Definitions of this Code.” [The “Convention” referred to in the second sentence is presumably the 1966 ILLC?]. It could cause confusion if we now changed Ls to L in SOLAS. If we are quite certain that it does need to be changed then it should be done in consultation with the IS WG/CG who will need to change footnote 35. Q16A. Would you now agree that we should maintain consistency with the 2008 IS Code and retain the use of Ls in Reg. 5.2? Yes Germany, China, Finland, Italy, Japan, France (with comments), CLIA, Sweden, Denmark No MI, US (with comment), RINA (with comments), Norway (with comment), UK (with comment) Comments / Objections?:MI: No, concur with Spain that a unifying exercise is required to use L throughout the relevant instruments. US: Although no strong view, our general preference would be to switch to L (and adjust the IS Code footnote accordingly). RINA: The determination of LCG, VCG, TCG are obtained from the result of the inclining experiment as required by regulation 10.1 of the 1966 ILLC. The process by which a decision not to hold an inclining experiment is included in both the ILLC and SOLAS convention. With hindsight the duplication of the information to be supplied to the master, required by the ILLC and the intact stability information required by SOLAS is unfortunate. There is no definition of Ls in the ILLC. It is therefore difficult to understand to see how Ls, a damage stability nomenclature, can be used in what is an intact stability situation. It would appear that this position has arisen due to the inclusion of Ls in the 2008 IS Code. However if this was an oversight it should not be perpetuated in the 2009 SOLAS amendments. France: It seems that the intent of IS Code was to be in line with SOLAS 2009, but the wording of the foot note is unclear. The sentence “For ship to which the convention applies and for other ships…” seems to cover all ship types, so the only reasonable interpretation would be that Ls would be used only for ships to which SOLAS 2009 damage stability requirements apply. In this case, Ls should be retained, but additional sentence should be added: “If ship is excluded from the application of the damage stability regulations in part B-1, Ls will be replaced by L”. Norway: However, referring to Q2A; if it is decided to use a unified definition of LBP instead of L, we will opt for consistency with this value, not a footnote in the IS Code. UK: We are not convinced that there is any benefit in retaining the use of Ls in Regulation 5.2. Round 2 Discussion: Although 9 members were in favour of keeping Ls following the coordinator’s previous comments on the footnote to the 2008 IS Code, it seems that there is still quite strong support (5) for using L instead of Ls in regulation 5.2 for consistency. If we ignore the 2008 IS Code footnote (35) for the moment, reg. 5.2 allows dispensation from the need to carry out an inclining test on an individual cargo ship. Regulation 5.1 already defines the length of cargo ships in terms of length (L) of 24 m and upwards. As stated in Q62, below, it has been noted that when ship length is being used as a “threshold”, as in this regulation, then it is more consistent with the rest of SOLAS to use L, which is a figure known earlier in the design phase, than Ls. We still need to consider possible differences between L and LBP (see Q2 and Q3), (now hopefully resolved?) Circ 1158 uses LBP for determining the % threshold (see below).

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Could we therefore agree that the other length thresholds in reg. 5.2 (50 m and 160 m) should refer to L and that it would therefore be consistent to use L for the % deviation of lightship LCG, as originally proposed by Norway. If so, we should perhaps consider changing the text to make this absolutely clear:………………. A weight survey shall be carried out upon completion and the ship shall be inclined whenever in comparison with the data derived from the sister ship, a deviation from the lightship displacement exceeding 1% for ships of 160 m or more in length (L) and 2% for ships of 50 m or less in length (L) and as determined by linear interpolation for intermediate lengths or a deviation from the lightship longitudinal centre of gravity exceeding 0.5% of [Ls] [L] is found. If we can agree to these changes then we should advise the S-C that footnote 35 to the 2008 IS Code will need to be altered:35

[For the purpose of paragraphs 8.1.2 and 8.1.5 the length (L) means the subdivision length (LS) as defined in regulation II-1/2.1 of the 1974 SOLAS Convention, as amended]. For ships to which the Convention applies, and for other ships the length (L) means the length of ship as defined in 2.12 of the Purpose and Definitions of this Code.

Q16B (for SLF53 S-C and WG). Can we agree to the changes made to reg. 5.2 as shown in the round 2 discussion, above, and to notify the S-C that a change is needed to footnote 35 in the 2008 IS Code, as shown above, for consistency? Yes No Further comments?:At SLF 53, the WG agreed to replace Ls with L in Reg. 4.2 and to advise the S-C that the following change will therefore be needed in footnote 35 of the 2008 IS Code:35 [For the purpose of paragraphs 8.1.2 and 8.1.5 the length (L) means the subdivision length (LS) as defined in regulation II-1/2.1 of the 1974 SOLAS Convention, as amended]. For ships to which the Convention applies, and for other ships the length (L) means the length of ship as defined in 2.12 of the Purpose and Definitions of this Code.

Clarification of the “length” terms in the 160 m and 50 m thresholds as also being L, was not considered necessary. Q16C (for Round 4 questionnaire). This is more of a housekeeping issue but does anybody know who is responsible for advising the IS group of our decision which will mean a change to footnote 35 of the 2008 IS Code? Will the secretariat do this automatically or is it up to the coordinators? Comments?:US: We suggest this item be included in the SDS CG report as a specific action requested of the S/C; i.e. request the S/C instruct the IS WG to consider this item at SLF 54. Note: In the published IS Code this is no longer footnote 35; it is a footnote to Part B regulation 8.1.2. In addition, it seems the entire footnote should be deleted (not just the first sentence). China: No comments RINA: SLF 53 /WP. 6 ”The group ........and consequently agreed that footnote 35 to the 2008 IS Code should be altered in order to reflect this change.” It would have been expected that this would have been included in the Actions on the Sub Committee but this was not the case. Conclude that this action will need to be reintroduced by the CG at SLF 54?

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Denmark: No. UK: Suggest that the coordinators report to the secretariat the need of the said revision. Round 6 Discussion: Thank you all for your comments and to the US for noticing that there is a difference in the treatment of the footnotes between MSC.267(85) (where all the footnotes are sequentially numbered) and the published 2008 IS Code where asterisks are used throughout. We are not sure why this change was made but to ensure there is no confusion we will specify both footnote 35 in Res. MSC.267(85) and the asterisked footnote in 2008 IS Code, Part B, reg. 8.1.2 in our report to the S/C when we ask them to notify the IS WG. The US suggests that the entire footnote in the IS Code should be deleted. It is therefore proposed that we should also ask the S/C in our report that the IS WG be instructed to consider the validity of this entire footnote in the light of the changes we have agreed to the use of L and Ls in SOLAS2009. Q16D (for Round 6 Questionnaire). Do you agree with the action outlined in bold type in the discussion above)? Japan, CLIA, RINA, Finland, Norway, Germany, US, Italy, UK, France, Yes? Denmark, China, EC (Yes, the rest of the text of the footnote seems superfluous.) No? Are there any further comments? RINA: Agree with the US suggestion. Germany: A general overview would be good, where the use of L and Ls has been changed. Q16 This issue was included in the report to the S/C (Ref. 54/8/1 paragraph 15.3) with an invitation to take action as appropriate. 3 The Administration may also allow the inclining test of an individual ship or class of ships especially designed for the carriage of liquids or ore in bulk to be dispensed with when reference to existing data for similar ships clearly indicates that due to the ship’s proportions and arrangements more than sufficient metacentric height will be available in all probable loading conditions. 4 Where any alterations are made to a ship so as to materially affect the stability information supplied to the master, amended stability information shall be provided. If necessary the ship shall be re-inclined. The ship shall be re-inclined if anticipated deviations exceed one of the values specified in paragraph 5. 5 At periodical intervals not exceeding five years, a lightweight survey shall be carried out on all passenger ships to verify any changes in lightship displacement and longitudinal centre of gravity. The ship shall be re-inclined whenever, in comparison with the approved stability information, a deviation from the lightship displacement exceeding 2% or a deviation of the longitudinal centre of gravity exceeding 1% of [Ls] L [Q17] is found or anticipated. Regulation 5.5 (ref. SLF 52/17/6 - Norway) Replace Ls with load line length (L) for consistency (see Regulation 2.9 and 2.13 for details). Q17. Do you agree that L should replace Ls as in Regulation 5.2? Yes

Japan, MI, Norway, Spain, Denmark, UK, US, Sweden

No

China, Finland, Italy

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Comments?:Germany: A uniform, comprehensive approach shall be taken. Spain: See Q.16 Denmark: Believes this question refers to Reg. 5.5. Prefer LBP mainly because unified interpretation below uses LBP; this is commonly available data in ship’s documents. Round 1 Discussion: Again there is good support for the proposal to replace Ls with L, with Spain referring to their response to Q16 but 3 members oppose it and 2 have not indicated a preference. However, the coordinators’ argument for consistency with the 2008 IS Code (see Q15) is also valid for Reg. 5.5, which is identical to Ch 8.1.5 of the IS Code having the same footnote (35). Therefore we must ask the same question as for Q16. Q17A. Would you now agree that we should maintain consistency with the 2008 IS Code and retain the use of Ls in Reg. 5.5? Yes Germany, China, Finland, Italy, Japan, France (with comment), CLIA, Sweden, Denmark No MI, US (with comment), RINA, Norway (with comment), UK Comments / Objections?:MI: No, concur with Spain that a unifying exercise is required to use L throughout the relevant instruments. US: Although no strong view, our general preference would be to switch to L (and adjust the IS Code footnote accordingly). RINA: See response to Q16A. France: Same definition as for reg 5.2 should be applied. Norway: The text in the IS Code is only a footnote in the non-mandatory part that can easily be changed as an editorial matter. UK: We are not convinced that there is any benefit in retaining the use of Ls in Regulation 5.2. Round 2 Discussion: This will now depend on the outcome of Q16B, above. To maintain consistency we should accept Norway’s original proposal to replace Ls with L in reg. 5.5. Q17B (for SLF53 S-C and WG). If we answer “Yes” to Q16B, then do you agree that we should also change Ls to L in reg. 5.5 as originally proposed by Norway? Yes No Further comments?:The SLF 53 WG agreed to change Ls to L. Q17. AGREED AT SLF 53: RECOMMEND ACCEPTANCE AT SLF 54 6 Every ship shall have scales of draughts marked clearly at the bow and stern. In the case where the draught marks are not located where they are easily readable, or operational constraints for a particular trade make it difficult to read the draught marks, then the ship shall also be fitted with a reliable draught indicating system by which the bow and stern draughts can be determined. Regulation 5 − Intact stability information Reference is made to MSC/Circ.1158 (Unified interpretation of SOLAS chapter II-1) regarding lightweight check. [Included below for easy reference:-]

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MSC/Circ.1158 24 May 2005 UNIFIED INTERPRETATIONS TO SOLAS CHAPTER II-1 PART B-1 REGULATION 5 (PREVIOUSLY SOLAS CHAPTER II-1 REGULATION 22) REGARDING STABILITY INFORMATION FOR PASSENGER AND CARGO SHIPS LIGHTWEIGHT CHECK 1 The Maritime Safety Committee, at its eightieth session (11 to 20 May 2005), with a view to providing assistance to the Administrations in the implementation of the requirements of the 1974 SOLAS Convention and in order to ensure the uniform application thereof, approved the unified interpretations of the Convention, as set out in the annex. 2

Member Governments are urged to:

.1 take note of the annexed unified interpretations and use them when applying the relevant requirements of the 1974 SOLAS Convention; and .2

bring the annex unified interpretations to the attention of all interested parties.

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MSC/Circ.1158 ANNEX 1.

A sister ship is a ship built by the same yard from the same plans.

2. A lightweight check is considered the acceptable means of being satisfied that the data from a lead sister ship’s inclining test can be used for a subsequent ship. The Administration may request regular repeats of inclining tests and/or require each individual passenger ship to be inclined, as detailed below. 3. For any newly built sister ship with known differences from the lead sister ship, a detailed weights and centres calculation to adjust the lead ship’s lightship properties should be carried out. The validity of the calculated lightship properties should be assessed by carrying out a lightweight check unless the implications regarding the stability of the ship indicate that an inclining test should be performed. The acceptable deviation of lightship displacement should be: For L≤50m

2% of the lightship displacement of the lead ship.

For L≥160m

1% of the lightship displacement of the lead ship.

For intermediate length by linear interpolation. In addition, the deviation of lightship longitudinal centre of gravity should not exceed 0.5% of the LBP of the lead ship. Where the deviation exceeds either of these limits, an inclining test should be carried out. Where the deviation is within these limits the actual lightship weight and longitudinal centre of gravity derived from the lightship check should be used in conjunction with the higher of either the lead ship’s vertical centre of gravity or the calculated value. 4. For a ship in service which undergoes alterations with calculable differences in lightship properties which materially affect the stability information supplied to the master, a detailed weights and centres calculation to adjust the lightship properties should be carried out. To avoid an inclining test, the deviation of lightship displacement should not exceed 2% of the original approved lightweight or 2 tonnes, whichever is greater, or that approved following the most recent major alteration or conversion. In addition, the deviation of lightship longitudinal centre of gravity from the original or that approved following the most recent major alteration or conversion should not exceed 1% of the LBP of the ship. Where the deviation exceeds either of these limits, an inclining test should be carried out. Where a ship is within these limits the calculated values of lightweight, lightship LCG and lightship VCG should be used in all subsequent stability information supplied to the master. 5. For all passenger ships, a lightship survey should be carried out at periodical intervals not exceeding five years to verify any changes in lightship displacement and longitudinal centre of gravity. The ship should be re-inclined whenever, in comparison with the originally approved stability information or that approved following the most recent major alteration or conversion, the deviation of the lightweight and/or lightship longitudinal centre of gravity exceeds the limits in paragraph 4 above. Where a ship is within these limits, the values of lightweight and lightship LCG derived from the lightship survey should be used in conjunction with the VCG derived from the most recent inclining experiment in all subsequent stability information supplied to the master.

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Regulation 5-1 Stability information to be supplied to the master * [Coordinator’s Note: Norway is proposing several changes and a re-organization of Regulations 5-1 and 7 and the EN. A clean version of these proposals without notes and comment is contained in Appendix 1 at the end of this document for easy reference. Appendix 2 shows a clean version of the current text of SOLAS 2009 Regs 5-1 and 7 with EN, also for reference]. 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) [and maximum permissible trim] versus draught which assures compliance with the relevant intact [stability requirements of part A of the 2008 IS Code] and [relevant] damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

Regulation 5-1.2.1 (ref. SLF 52/17/4 Annex A para. 1.1 - Norway) Add words shown underlined above to emphasize that there will be trim limitations. R5-1.2.1 (Need to emphasize trim limits) Q18. Do you agree that the underlined text in square brackets should be added? Yes No

China, Finland, Germany, Japan, MI, Norway, CLIA, Italy, Denmark, UK, US, Sweden Spain

Comments?:Finland: Further support to add into end of 5-1.3; Applied trim values shall coincide in all stability information intended for use on board. New paragraph proposed to insert 5-1.4; The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability of these regulations. Information not required for determination of stability and trim limits should be separated from this information. Existing paragraph 5-1.4 and 5-1.5 to be renumbered 5-1.5 and 5-1.6 In reg 4 footnote after proposed modifications there still remain ships under other stability instruments to fulfil damage stability regulation. Therefore proposed new paragraph 5-1.4 will be preferred. Japan: The trim range limited in accordance with 2008 IS code should also be included. Spain: The proposal of the curve representing maximum permissible trim versus draught is not very clear, in our opinion. See Q21 for further details. Denmark: It has to be made clear what is intended by curves or tables of maximum permissible trim, and the ones presented later in the document are potentially confusing for ship’s staff.

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Round 1 Discussion: Although there is very strong (12/1) support for Norway’s proposal there are still some practical difficulties in providing the draught/trim/limiting GM/KG curves in a form easily usable on board especially if we want to consolidate all the intact and damage criteria appropriate to particular ships across the operating range of draughts and trims into one simple graph or table. We are very grateful to Norway for all the work they have done on many questions relating to the provision of curves of minimum GM or maximum KG for use on board (refer to Appendix 1 at the end for their full proposals). Also thanks to Finland for their proposals for ensuring that trim is dealt with consistently in all the relevant intact and damage regulations. This is a rather complicated issue and it must be doubtful as to whether a satisfactory overall solution can be obtained within the CG before SLF 53. To contribute to the discussions here are some further points for consideration:1) Regarding Japan’s point, the requirements of the 2008 IS Code regarding trims / GM are:2.1.7 If curves or tables of minimum operational metacentric height (GM) or maximum centre of gravity (VCG) are used to ensure compliance with the relevant intact stability criteria those limiting curves shall extend over the full range of operational trims, unless the Administration agrees that trim effects are not significant. When curves or tables of minimum operational metacentric height (GM) or maximum centre of gravity (VCG) versus draught covering the operational trims are not available, the master must verify that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition taking into account trim effects.

2) There does appear to be a conflict between the 2008 IS Code requirement for the limiting curves to cover the range of operational trims in contrast with the S2009 amendments in Reg 51.3 which only require the influence of trim to be taken into account when the operational trim range exceeds +/- 0.5% of Ls [L]. 3) Reg 5-1.4 only describes how to calculate the minimum GM (maximum KG) curves for the subdivision index and suggests that the limiting values are simply to be those used in the calculation of si at each of the 3 designated draughts. It is now quite usual for software to adjust the GM/KG at each designated draught to give an overall critical GM/KG curve such that A=R. 4) There could be a significant difference between minimum GM and maximum KG curves when trim variation is taken into consideration since KM varies with trim whereas KG does not. If a ship has an operational trim of < 0.5% Ls then for damage stability the level trim minimum GM only needs to be calculated. This means that the ship could operate at, say, 0.4% Ls bow trim and still be applying the level trim limiting GM value for the A>=R criterion for a particular draught. 5) A numerical example may illustrate the problem more clearly. Suppose the minimum required GM for A>=R at level trim is 1.2 metres at a particular draught and the level trim KM at the same draught is 11.36 m giving a maximum allowable KG of (11.36 – 1.2 = 10.16 m) and suppose the actual KGf is 10.14 metres giving a margin of compliance of 0.02 metres. At a bow trim of 0.4%L, the minimum required GM remains at 1.2 metres according to the current regulations, whereas the actual KM at the same draught may now be only 11.31 metres. According to this, the maximum allowable KG will be (11.31 – 1.2 = 10.11 m) giving a non-compliance margin of 0.03 metres. So use of level trim minimum GM up to a trim of 0.5%L indicates compliance whereas in fact the condition would be non-compliant if maximum allowable KG’s were to be used. This illustrates the uncertainty which surrounds use of using fixed level trim limiting GM’s in a situation of varying operational trim. This error could be removed or reduced if limiting GM/KG points were calculated for level trim, maximum operational bow trim and maximum operational stern trim at each of the 3 draughts ds, dp and dl. It is suggested that a minimum of 3 trims should always be calculated but this could be increased to give a suitable spread of calculated points for interpolation at each of the 3 draughts if the maximum operational bow or stern trim were excessive (say > +/- 0.5% L).

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Proposed Action: Acknowledging the strong support for Norway’s proposal, but also Finland’s alternative and the points raised by Japan, Spain and Denmark it is proposed that we examine the overall situation with regard to the provision and presentation of limiting KG/GM curves for a range of draughts and trims in the context of the points raised in the above discussion and in the questions raised on this issue below (Q20 – 25) then try to draw some conclusions at the end, starting with Norway’s proposals in Appendix 1. So please also refer to Appendix 1 for further discussion on this and related issues. Q18A. Any comments at this stage?:Comments received: France: Two different subjects are mixed : - First question concerning the indication of trim limit is still valid. We would support the proposal from Finland to include it in paragraph 3: “Maximum permissible trim versus draught which assures compliance with the relevant intact and damage stability requirements shall be included in stability information”. We don’t support the necessity to add a new paragraph 5-1.4, considering that it is already included in paragraph 5-1.2.1. - Question on the influence of trim on the results is an additional question. The example presented by coordinators highlights the fact that generally, if constant GM or KG is kept for a trim range, presentation in max KG is more favourable for trim by bow and presentation in GM is more favourable for trim by stern. Much higher difference may be observed (up to 0.20m). So limit of 0.5% of Ls may be questioned. Norway: Norway’s proposals are related to the decision made by SLF at an early stage of the revision work that only one trim shall be used for dl. The problems we see now as consequences of that principle were obviously not foreseen at that time. Judging by the comments collected by this questionnaire we believe it should be acceptable to act on this experience and discuss whether it would in fact be better to reverse that decision and re-write the regulations accordingly. As this would take some time we believe our proposals will still be useful as a stop-gap measure until updated provisions are available. CLIA: No comments. Additional comments received from CLIA/CCSF between Round 1 and Round 2: Regulation 5-1 The use of separate GM limiting curves for different trims, resulting in an envelope curve needs to be reconsidered in view of the Norwegian proposals in SLF52/17/4. The use of an envelope curve seems to be not adequate, but simultaneously the misuse of the regulation, in particular for cargo ships, has to be prevented by the explanatory notes. Coordinator’s Comments: Again, please refer to Appendix 1 for further discussion of this issue. CG Member’s Comments?:France: See Q21. CLIA: See comments to Appendix 1, Question 1. Round 2 Discussion: Many thanks to France, Norway and CLIA for their additional comments. We will continue the discussion under new Appendix 3 which includes further proposals for presenting limiting GM/KG curves/tables to allow for the operating trim and all the criteria as an alternative to Norway’s proposal in Appendix 1. See also Q20, 21, 23, 25 and 26. Post SLF 53 Discussion:- In the WG it was agreed to accept Norway’s original proposal to add “and maximum permissible trim” as shown in red above. Q18. AGREED AT SLF 53: RECOMMEND ACCEPTANCE AT SLF 54

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.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability [according to the requirements of part A of the 2008 IS Code] and stability after damage.

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456); [Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706) SLF 53 WG3 agreed this deletion (see Q6)]; and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

Q19. Will the changes highlighted in yellow to Reg. 5-1.2.1 and 5-1.2.3 be automatically included in the next Consolidated Edition? See also Reg. 5.1 (Q14). Yes

Finland, Germany, Japan, MI, Norway, CLIA, Italy, Spain, UK, Sweden

No

China, Denmark, US

Comments?:US: They will not automatically be added because they were not part of the MSC 85 adopted amendments. However, we support the changes as proposed / highlighted in yellow. Round 1 Discussion: Thank you for this clarification, US. We cannot identify the source of these amendments. Q19A Given the US’ clarification, would you now agree that the texts highlighted in yellow in Regs 5-1.2.1 and 5-1.2.3 should be included? Yes MI, Germany, Finland, US, Italy, Japan, RINA, Norway, CLIA, UK, Sweden, Denmark No France (with comment) Comments?:France: Part A of 2008 IS code is defined as the minimum requirement in regulation 5.1. Additional criteria may be applied, so it seems not to be a good option to repeat regulation 5.1. Round 2 Discussion: The inclusion of the text change has almost total support (12-1) but France correctly states that there is already a footnote referring to the 2008 IS Code under regulation 5.1 so perhaps this is unnecessary repetition. Propose this question be put at SLF 53. Q19B (for SLF53 WG). Is there support for France’s view that the text changes highlighted in yellow in reg. 5-1.2.1 and 5-1.2.3 are unnecessary? Yes No Comments?:At the SLF 53 WG the proposed text insertions referring to the intact stability requirements of the 2008 Code were deemed unnecessary in the light of France’s comment on the footnote to Reg. 5.1 and are therefore deleted. Q19 NFA at SLF 54 Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to

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those described in regulation 5-1.4, should also be taken into account when developing this information. 3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of [Ls] [L]. [Applied trim values shall coincide in all stability information intended for use on board.] [Coordinator’s Note – reason for underlined change given in SLF 52/17/4, Norway, see below. Further note post SLF 53 – it was finally agreed to change Reg. 5-1.3 to read as shown in red:-] 3 The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board. Regulation 5-1.3 (ref. SLF 51/3/2 – US and Sweden) This provision that the influence of various trims on the stability information need only be taken into account if the operational trim range exceeds +/- 0.5% of Ls should be revisited (also in regulation 7.2). Associated comment from the United Kingdom: In our experience, particularly with ro-ro passenger ships, the influence of trim can become important at much lower % Ls values. Regulation 5-1.3 (ref. SLF 52/17/4 Annex A para. 1.2 - Norway) Add words shown underlined above to ensure consistent use of trim. Regulation 5-1.3 (ref. SLF 52/17/6 - Norway) Replace Ls with load line length (L) for consistency (see Regulation 2.9 and 2.13 for details). Q20. (a) Do you agree that L should replace Ls in 5-1.3 as in Regulation 5.2 and 5.5? (b) Do you agree that the underlined sentence in square brackets should be added? (c) Does the operational trim range of +/- 0.5% need to be re-considered? (a) Please answer Yes or No:Yes: MI, Norway, Spain, Denmark, UK, US, Sweden, Japan No: China, Finland (see Q17), Germany, CLIA, Italy (b) Please answer Yes or No:Yes: MI, Norway, CLIA, Spain, Denmark, UK, Sweden No: China, Finland, Germany, Japan, Italy Abstain: US (may need further information) (c) Comments / suggestions?:To be re-considered: Finland, Denmark, UK Not to be re-considered: China, Japan, MI, Norway, Italy, Sweden Finland: Ro-pax type vessels are very sensitive to change of trim. Germany: A uniform, comprehensive approach shall be taken. Norway: No; not until a more detailed justification has been presented. In particular it must be investigated whether a change could affect the calibration of the R-formulas in regulation 6. Spain: We need further/additional details. To calculate only one limiting GM curve (or the minimum possible number of GM limiting curves) is more intuitive, simply and preferable. Anyway, if clearly demonstrated that for a specific type of vessel +/- 0.5% is too much, we can change the limit for this type of vessel. Denmark: Yes, it is in any case worth checking the influence of trims on the attained index, particularly if GM has been lowered to obtain A=R.

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UK: We suggest that until such time that Passenger Ships (particularly ROPAX vessels) survival assessment is revised satisfactorily and indicates otherwise, the range should be +/- 0.2%. US: We think additional justification is needed to re-consider the 0.5% trim threshold. Sweden: Not at this time, but if it can be clearly shown that there is a potential risk for these vessels the trim range for specific types of vessel can be re-considered. (a) Round 1 Discussion: A majority of 8/5 think that L should replace Ls in Regs 5-1.3. However, in the light of the discussions to Q16 and 17, where there now appears to be a strong case for using Ls, should we not be consistent and continue to use Ls throughout Regulation 5? Q20(a)A. Would you agree that it would be preferable to use Ls throughout Reg. 5 for reasons both of internal consistency and consistency with the 2008 IS Code footnote 35? Yes Germany, Finland, Italy, Japan, CLIA, Sweden, Denmark No

MI, US (with comment), RINA, Norway (with comment), UK (with comment)

Comments?:US: Although no strong view, our general preference would be to switch to L (and adjust the IS Code footnote accordingly). RINA: See response to Q16A. France: This could be accepted, but this paragraph seems to apply to all ship types, so as for reg.5, it should be added that for ships not complying with damage stability requirements of Part B-1, Ls will be replaced by L. Usual practice for ship complying with damage stability regulations in other IMO instrument is to define required GM for trim variation of less than 0.5% of Ls. So it may be considered that trim range up to 0.5% of Ls is only applicable to ships complying with damage stability requirements of Part B-1. In this case, “in case where the operational trim range exceeds +/-0.5% of Ls” should be deleted from paragraph 3 which applies to all ships. Norway: The text in the IS Code is only a footnote that can easily be changed as an editorial matter. UK: We think that the use of Ls, which is essentially only for internal subdivision layout “mapping”, does not bring any real benefit to the master in assessing the loading characteristics other then adding further complications; in the case of Regulation 5 and 5-1 it can easily be avoided. (a) Round 2 Discussion: If we agree to the proposal in Q16 and Q17 then for consistency we should change Ls to L (as in reg. 5.2 and 5.5) and ask the S-C to note that the 2008 IS Code footnote 35 will need to be amended. Q20(a)B (for SLF53 WG). For consistency with reg. 5.2 and 5.3, would you agree that we should also use L in place of Ls in reg. 5-1.3? Yes No Comments?:-

(b) Round 1 Discussion: A majority of 8/5 are in favour of adding text to Reg. 5-1.3 to clarify that trims for all the relevant stability regulations must be accounted for. The discussion under Q18 indicates that there may be some difficulties in trying to reconcile the +/- 0.5% operating trim range referred to in this regulation with that from, for example, the intact stability 2008 IS Code requirements, where either the operational trim range of whatever magnitude must be covered at all draughts or special loading calculations must be carried out if the loading condition lies outside the pre-determined range (impractical for damage stability, but see Reg. 5-

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1.5). Another point which should be clarified is whether the +/- 0.5%L trim range only refers to the calculation of the “A>=R criterion” or does it also include Reg. 6.1 (0.9R or 0.5R at each partial index) and also the limiting GM/KG curves derived from the minor damage regulations (Reg. 8) and the double bottom regulations (Reg. 9)? If we change “B1 through B4” to read “B1” (see Q6), then Reg. 9 will lie outside the range of damage stability regulations as defined in Reg. 4.1 In many ways it would make consistency with all the other intact and damage regulations easier if we could remove the reference to +/- 0.5% L altogether and re-word Reg. 5-1.3 to read simply:“3 The stability information shall show the influence of [various] trim[s] [on limiting KG/GM] [in cases where] [across] the operational trim range [exceeds +/- 0.5% of Ls ]”. Q20(b)A. Could you accept this modification to Reg 5-1.3 as a technically valid alternative to Norway’s original proposal for dealing with trim in all the relevant stability regulations? Yes MI, Italy, Japan, France (with comments), CLIA, UK, Sweden No

Germany, Finland, Norway, Denmark

Comments?:France: This change is a major change because in this case, reference to 0.5%Ls would only apply to Part B-1 of SOLAS (specified in reg 7.2). This is however more in line with usual presentation of results and it can be considered that this presentation of constant required GM for a trim range can only be applied in the context of probabilistic damage stability. This would cancel comments on Q20(a)A. It would be necessary to explain how to combine requirements of SOLAS Part B-1 for which required GM is applicable to a trim range with intact stability criteria calculated for different trims. (b) Round 2 Discussion: Many thanks to France for their additional comments. It is agreed that this is a major change which also will involve other regulations in Part B-1 (including changes to reg. 7.2, as mentioned by France). We will continue the discussion under new Appendix 3 which includes further proposals for presenting limiting GM/KG curves/tables to allow for the operating trim and all the criteria as an alternative to Norway’s proposal in Appendix 1. It is based on the discussion at the end of Appendix 1 (ref. Appendix 1Q1) which had some support. See also Q18, 21, 23, 25 and 26. (c) Round 1 Discussion: Only 3 members felt that the +/- 0.5% trim range should be reconsidered with a further 4 saying that more justification should be provided first. Some reasons for re-consideration have been outlined in the discussions under Q18 and 20(b) above but Norway’s point about the possible need to re-calibrate “R” is potentially serious, perhaps requiring expert advice from the HARDER team. If there is a positive response to Q20(b)A, however, we could remove the +/- 0.5% restriction altogether which would simplify harmonisation with the other intact and damage stability regulations. Proposed Action: As for Q18, it is proposed that we examine the overall situation with regard to the provision and presentation of limiting KG/GM curves for a range of draughts and trims in the context of the points raised in the above discussion and in the questions raised on this issue below (Q21 – 25) and then try to draw some conclusions at the end, starting with Norway’s proposals in Appendix 1. So please also refer to Appendix 1 for further discussion on this and related issues.

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Q20(c)A. Any comments at this stage?:Comments received: US: Comment regarding possible need to re-calibrate “R”: in our view this is not a significant concern because the original process to establish the “R” formulas was not that precise in reality (selection/number of sample ships; assumptions made for sample ship calculations; R regression; etc.). France: Trim range of 0.5% Ls may be estimated as too large considering the possible discrepancy between required GM and maximum KG when ship trim differ from reference trim. In practice, index which would be attained with the maximum allowable trim, including the range of +/- 0.5% Ls is not known. A more strict approach would be to verify that with the maximum allowable trim applicable to GM/KG curve, attained index A would not be less than [0.98]*R, A being weighted on the 3 drafts. To illustrate the influence of trim on calculated attained index, you will find enclosed, an example of variation of attained index with the trim variation, assuming constant GM and constant KG. (for a large cruise ship with Ls = 320m; trim positive by bow) :-

Attained index 0.90 0.89 0.88 0.87 0.86 0.85 0.84 0.83 0.82 0.81 -1.5

-1

-0.5

0

0.5

1

trim 1.5

Constant GM Constant KG If a limit of [0.98] R was given for attained index, maximum trim by stern would be of about -1m if maximum KG curve is adopted and -0.4m if minimum GM is adopted. END of COMMENTS by FRANCE (c) Round 2 Discussion: Many thanks to the US and France for their comments regarding the somewhat approximate basis for the derivation of “R” and the considerable influence of trim on “A” respectively. We also share France’s concern with the difference between using GM (trim dependent) and KG (independent of trim). These comments would tend to confirm that “R” is an average, global measure of safety. To be more precise perhaps the formulae for “R” should have shown some variation with trim too. As it is we are currently comparing an attained index “A” which can vary with trim against an averaged “R” derived by regression from data which was not correlated to show the variation of damage stability with trim. For this reason we have proposed in Appendix 3 a series of changes to the regulations and EN which may go some way towards reducing these problems and help towards better integration of the intact and damage stability limiting GM/KG curves/tables. Please refer to Appendix 1Q1 and Appendix 3 for further discussion.

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Post SLF 53 – it was finally agreed to change Reg. 5-1.3 to read as shown below :3 The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board. This change also resolves Q20(a) and 20(b). AT THIS POINT THE WG DECIDED TO LEAVE FURTHER QUESTIONS RELATING TO THE PROVISION OF STABILITY INFORMATION TO THE MASTER FOR CONSIDERATION BY THE CG IN 2011. SO QUESTIONS 21 THROUGH 26 ARE AT PRESENT COVERED BY THE PROPOSED ALTERNATIVES IN APPENDIX 1 AND 3 and THESE TOPICS WILL BE RE-OPENED BY THE CG IN ROUND 5. PLEASE SEE APPENDICES 1 to 5 AT THE END OF THIS DOCUMENT.

FOR SLF 54 IT IS SUGGESTED THAT ATTENTION IS FOCUSSED ON APPENDIX 5 WHICH CONTAINS NORWAY’S REVISED PROPOSALS AS THESE WERE GENERALLY PREFERRED BY THE 2011 CG. RE-START WG/SLF 53 DECISIONS AND WORK OF 2011 CG AT R7.3 (CLIA Q2).

[4

For ships which have to fulfil the stability requirements of [part B-1] [these regulations], [Coordinator’s Note: this change is proposed in SLF 51/3/2 and supported by Norway in SLF 52/17/6, see below] information referred to in paragraph 2 is determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. [If the subdivision index is calculated for different trims, several required GM curves will be established in the same way]. [If the subdivision index is calculated for different trims, a single envelope curve for required GM should be developed. If required KG is produced, then several required KG curves will be established]. [Coordinator’s Note: the change to the last sentence is proposed in SLF 51/3/2 for the reasons below).]

] -----------Regulation 5-1.4 (ref. SLF 51/3/2 – US and Sweden) In order to allow/be consistent with [an earlier] proposal from Norway (under regulation 7.2 below) regarding calculation of A for different trims, it is proposed to re-word the last sentence of this paragraph as follows: “If the subdivision index is calculated for different trims, a single envelope curve for required GM should be developed. If required KG is produced, then several required KG curves will be established.” ------------

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Because the limiting GM (or KG) guidance provided to the master in accordance with regulation 5-1 could be impacted by the requirements in regulations 8 and 9 (and the partial attained subdivision indices in regulation 6.1), the following text was added to the Explanatory Notes under regulation 5-1.2: “Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in paragraph 4, shall also be taken into account when developing this information.” [Coordinator’s Note: This change to the EN has already been made.] In this regard, the text “stability requirements of part B-1” in regulation 5-1.4 could be replaced by “stability requirements of these regulations” (because regulation 9 is located in part B-2, not part B-1). -----------Norway now proposes (in SLF 51/17/4) to replace the whole of Regulation 5-1.4 with

[4

The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations. Information not required for determination of

]

stability and trim limits should be separated from this information. and introduce a new Regulation 5-1.5 (see below for reasons):-

[5

If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If it is intended to develop curves of maximum permissible KG it shall be ensured that the resulting maximum KG curves correspond with a linear

variation of GM. ] -----------Regulation 5-1.4 (ref. SLF 52/17/6 Annex - Norway) Document SLF 51/3/2 contains a proposal that the text “stability requirements of part B1” in the first sentence of regulation 5-1.4 could be replaced by “stability requirements of these regulations” (because regulation 9 is located in part B-2, not part B-1). This Administration supports this proposal. -----------Regulation 5-1.4 (ref. SLF 52/17/4 Annex A para. 1.3- Norway) Paragraph 5-1.4 does not cover damage stability limits resulting from deterministic regulations in cases where the footnote to regulation 4 has been applied. The information regarding stability limits in this paragraph can be simplified if the provisions regarding probabilistic calculations are kept in regulation 7 as far as possible and provisions regarding limit curves are kept in this regulation. The paragraph should be replaced in order to become independent of applied criteria:Proposed replacement for Regulation 5-1.4:The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations. Information not required for determination of stability and trim limits should be separated from this information.

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The principles concerning presentation of intact stability and GM/KG values in existing paragraph 4 are then moved into a new paragraph: Proposed new Regulation 5-1.5 (ref. SLF 52/17/4 Annex A para. 1.4 - Norway) If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If it is intended to develop curves of maximum permissible KG it shall be ensured that the resulting maximum KG curves correspond with a linear variation of GM. [Co-ordinators Note: If the above new regulation is accepted then existing paragraph 5-1.5 will have to be re-numbered 5-1.6]. 5 When curves or tables of minimum operational metacentric height (GM) versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) (ref. SLF 52/17/4 Annex C para. 1 - Norway) The notes regarding design of limit curves should be moved to this regulation to improve user-friendliness. 1.1 Amend title to accommodate the new paragraph. Delete reference to now empty 7.2. Proposed title to read:-

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“Regulations 5-1.3, 5-1.4 and 5-1.5” 1.2 The following is transferred from 7.2, note 3 and amended slightly where shown underlined:3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls. 1.3

Move the sketch from 7.2, note 3 accordingly:-

1.4

Add new note 4:-

4 As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed at the deepest subdivision draught ds and the partial subdivision draught dp respectively. The lowest values of each partial index As and Ap across trims will then be used in the summation of the attained subdivision index A according to regulation 7.1. At the light service draught the partial index Al is assumed constant. This will result in one GM limit curve based on the GM used at each draught. A trim limit diagram showing the assumed trim range is then developed as shown in the figure. Insert new figure:

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1.5

Add new note EN5:-

5 It is not required that the trim values at ds and dp coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked at 0.5% Ls [L] in excess of the largest calculated trims as shown in the figure. There will be no trim limits in the draught range between dl and dp unless the limiting GM is governed by other applicable intact or damage stability criteria. Comments received from CLIA/CCSF between round 1 and 2: Regulation 5-1.3 and 5-1.4 EN 2 It should be admitted that trim variations may be observed down to light service draft. In addition the GM limiting value for temporary conditions as described under regulation 2 has to be defined. Following alternative wording is proposed : “In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions ensuring that: - Intervals of 1% Ls are not exceeded between initial conditions at each draft. - The trim of each loading condition does not exceed 0.5% Ls difference in comparison with of one of the GM limiting curve at corresponding draft. - Verifications of regulation 8 and 9, if applicable, have to be done for all initial conditions with different trims. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range as a function of draft for application of the curve should be clearly stated. For any loading conditions, which result to a lower draught than dl due to ballast

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water exchange procedures, the same minimum GM value as for dl is to be taken”. Coordinator’s Comments: See also discussions in Appendix 1 for this issue. CG Member’s Comments?:France: The only new item is the last one concerning possibility to sail with a draft lower than dl. Proposition to consider the same GM value as for dl can be accepted. Round 2 Discussion: Thank you France. For completeness it would be very helpful if CLIA/CSSF could draft a set of revised regulations and EN covering reg. 5-1 and 7.2 to compare with those proposed in Appendix 1 and Appendix 3 to enable us to check their proposals more easily (see also CLIA’s comments under Q18A). Further comments?:-

Q21. Looking at Regulation 5-1.4 and the EN, it would appear that the amendments proposed in SLF 51/3/2 have been superseded by Norway’s proposals in SLF 52/17/4 and 52/17/6. The EN amendment in 51/3/2 would then be superseded by Norway’s revised EN, which also includes alterations to Reg. 7. A clean copy of all the proposed SOLAS text revisions and the changes to the EN are shown in Appendix 1 at the end of this questionnaire. Taking into account all the comments and notes above would you agree to the amendments to Regulation 5-1 with EN as proposed by Norway and as shown in Appendix 1? Yes No

China (but amended diagram needed), Finland (with comment), Germany (with comment), Japan, MI, Norway, Italy (with comment), US (with comment), Sweden CLIA, Spain, Denmark, UK

Comments / Alternative Proposals?:China: Reference is made to the trim limiting curve on page 3 of the annex of document SLF 52/17/4 Norway . Following figure is a hard-copy:

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This is a good proposal except that the two slope lines should be vertical and the trapezoid curve should be rectangular as the proposed figure by Norway uses two different sets of trim range in the calculation of partial index A for draught dp and ds respectively. Paragraph 2 of notes to Regulation 5-1.3 and 5-1.4 of MSC.281(85) says “then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading condition of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded”. I interpret this sentence in this way: draught dp and ds represent cargo loading conditions. “Operational range of trims” is the trim range starting from the least trim to the maximum trim on the sorted results of the trims of all cargo loading conditions. For example, if the real trims(i.e., without deduction of ±0.5%Ls for all cargo loading conditions are sorted and listed as below: -1.7%Ls, -0.4% Ls, 0.8% Ls, 1.6% Ls, 2.4% Ls Then the real trim range is -1.7% Ls ~2.4% Ls. Trim range of -1.2% Ls ~1.9% Ls. range should be applied in the calculation of partial index A for both dp and ds. This means the trim range of dp is the same as the trim range of ds. Although for the cargo loading conditions in the loading manual, the range of trims of the loading conditions of which the draft is ds may differ from the trims range of the loading conditions of which the drafts are less than ds, but in real operation the loading conditions may differ from the loading manual and the real trims of ds may exceed the used trim range and run into the trim range of dp. And the same case may occur for the used trim range of dp. Therefore using two separate trim ranges for draught dp and ds respectively is only of theoretical meaning and may not be consistent with the real operation. However, using the same trim range for both draught dp and ds as illustrated above is practical and concords with the explanatory notes. END of CHINA’s PROPOSALS Finland: Reg 5-1.4 (proposed 5-1.5, see Q18). Propose to add ; “If the subdivision index is calculated for different trims, an envelope curve with the highest GM values of the several required GM curves will be established in the same way. Agree with Norwegian proposed text into EN with the exception that calculations for trim variation also include variable trim for dl.

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Germany: has the following comments (the wording of the proposed text by NOR would need to be revised at several parts (including the diagram)!) a) We regard it as NOT meaningful that the light service draft dl is “fixed” in draft/trim (as a consequence Al is constant). Such restriction is in conflict with the general methodology of the probabilistic concept Î we regard dl as a “design parameter” which can be freely chosen by the designer. This includes that calculations for trim variation also include variable trims for dl. Any load cases need later to be verified to be within the limitations of trim/GM as a result of the damage stability calculation. This allows full flexibility for the designer and also inherits the required safety level b) With respect to Reg. 5.1.5 and the diagram we have the following comments: It is proposed that in the draft range between dl and dp NO trim limitation is valid. We are concerned for drafts close below dp as here per proposed definition no limit exists. We regard it as important that the trim limitation of +/- 0.5%L is valid for the entire draft range. This is to be seen in conjunction with our proposal that trim variations for dl are allowed. MI: Proposals acceptable as a complete package including use of ‘L’. Norway: It is realised that the second figure may be difficult to explain, however the principle for dealing with draughts below dp can not be dealt with without considering the effect on A and the calibration of the R-formulas. CLIA: This issue and the EN is handled in the CSSF work. Italy: Yes in principle but the lack of trim limits in the draught range between dl and dp is not acceptable. Spain: We do not agree with the proposal contained in points .4 and .5 (“As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed...”). The proposed limiting trim curve is not very clear for us. Anyway, if the group decides to accept the proposal, we have two comments: 1) What are the trim limits between dl and dp? 2) We suggest to change the axis (e.g. draught X axis and trim Y axis):

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END of SPAIN’s COMMENTS Denmark: In terms of presentation, I would be concerned that the trim limit diagram will be potentially confusing to ship’s staff, we prefer UK’s proposal for a trim limit diagram. Also Reg 51.5 should be the maximum of minimum GM limit curves. EN 3, Ls should be changed to L for consistency? We agree with the principle to clarify the regulations, but think that the presentation of max trim needs to be improved. UK: We are of the opinion that the details of each trim value used in the calculations should be presented as separate curves, alongside with the envelope curve (see Q25). US: Yes in principle; however some details need to be further considered and refined. e.g. The relationship between proposed new regulation 5-1.4 and the existing provision in regulation 5-1.2 is unclear to us; should these paragraphs be consolidated or should paragraph 4 precede paragraph 2? Also as indicated in the Coordinator’s Note, the new figure for EN paragraph 4 needs additional details / clarifications. Round 1 Discussion: In view of the complexity of the proposals and the number of comments received, this table has been duplicated in Appendix 1 which contains all the changes proposed by Norway. So please turn to Appendix 1 for continuation of the discussion and the Round 2 questions. This also applies to Q23 and Q25. Comments / Alternative Proposals?:France: To satisfy the requirement that “for all intended service conditions the difference in trim in comparison with the reference trim used for calculation will be less than 0.5% of Ls”, it may be necessary to made calculations at light service draft for different trims (see regulation 7.2 in

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explanatory notes). So we propose just to delete last sentence of paragraph (“ the partial index Al is considered constant for the purpose of these calculations”). Maximum KG and minimum GM are not equivalent. For some type of ship, trim variation may induce large variation in GM with a constant KG. For these ships, variation of attained index will be less if KG is kept constant with trim variation than if GM is kept constant (see comment to Q20). So it may be considered that use of maximum permissible KG curves would be more correct in these cases. If subdivision index is calculated for different trim, it would be better to establish the envelope curve on maximum permissible KG rather than minimum GM (See influence of trim on attained index presented with previous question). If one envelope KG curve is defined, required GM values will be different depending on the trim. (The reverse situation would happen if envelope curve is made on required GM.) In proposed diagram of trim versus draft, trim limit curves should cover the whole draft range and not be limited between dp and ds.

0.5%Ls

0.5%Ls

ds

dp 0.5%Ls

1%Ls

0.5%Ls

Calculated points Trim limits

Trim limit

0.5%Ls

1%Ls

dl

0.5%Ls

Round 2 Discussion: Many thanks to France for these new comments. As co-ordinators we have tried to overcome the problems raised by all members by proposing modifications to reg. 5-1 and 7 and the EN (see new Appendix 3 where we will continue these discussions). See also Q18, 20, 23, 25 and 26. Any further comments at this point?:-

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Regulation 6 Required subdivision index R * 1 The subdivision of a ship is considered sufficient if the attained subdivision index A, determined in accordance with regulation 7, is not less than the required subdivision index R calculated in accordance with this regulation and if, in addition, the partial indices As, Ap and Al are not less than 0.9R for passenger ships and 0.5R for cargo ships. Regulation 6.1 To demonstrate compliance with these provisions, see the Guidelines for the preparation of subdivision and damage stability calculations, set out in the appendix, regarding the presentation of damage stability calculation results. 2 For all ships to which the damage stability requirements of this chapter apply, the degree of subdivision to be provided shall be determined by the required subdivision index R, as follows: .1

In the case of cargo ships greater than 100 m in length (Ls):

.2

In the case of cargo ships not less than 80 m in length (Ls) and not greater than 100 m in length (Ls):

where Ro is the value R as calculated in accordance with the formula in subparagraph .1. .3

In the case of passenger ships:

where: N N1 N2

= N1 + 2N2 = number of persons for whom lifeboats are provided = number of persons (including officers and crew) the ship is permitted to carry in excess of N1.

____________________________

The Maritime Safety Committee, in adopting the regulations contained in parts B to B-4, invited Administrations to note that the regulations should be applied in conjunction with the explanatory notes developed by the Organization in order to ensure their uniform application. See notes under Regulation 4.3 regarding proposal by Germany to remove this footnote. [Coordinator’s Note:- Please also refer to Q.13.] *

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.4

Where the conditions of service are such that compliance with paragraph 2.3 of this regulation on the basis of N = N1+ 2N2 is impracticable and where the Administration considers that a suitably reduced degree of hazard exists, a lesser value of N may be taken but in no case less than N = N1 + N2

Regulation 6.2.4 Regarding the term “reduced degree of hazard”, the following interpretation should be applied: A lesser value of N, but in no case less than N = N1 + N2, may be allowed at the discretion of the Administration for passenger ships, which, in the course of their voyages, do not proceed more than 20 miles from the nearest land.

Regulation 7 Attained subdivision index A [Coordinator’s Note: For a summary of the changes proposed to Regulations 5-1 and 7 and the EN by Norway see Appendix 1, 2 and 3 at the end of this document]. 1 The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Regulation 7.1 (ref. SLF 52/17/4 Annex A para. 2.1- Norway) Modify paragraph 7.1 to allow for multiple calculations. Remove brackets in text: 1 An attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, weighted as shown, calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Q22.

Do you agree with the underlined proposed changes to Reg. 7.1?

Yes

China, Finland, Germany, Japan, Norway, CLIA, Italy, Spain, Denmark, Sweden No UK, US Comments?:MI: “Yes” to removal of brackets around ‘weighted as shown’ “No” to use of ‘An’ UK: We propose that the partial indices should be considered as “equally” weighted in considering all passenger vessels. US: We prefer the original text. Round 1 Discussion: The majority are in favour of Norway’s proposal, which is designed to alert the user to the fact that more than one index A may need to be calculated depending on trim, as described in Reg. 7.2. The US prefers the original text and the MI only accepts part of the proposal. The UK’s point is acknowledged but seems to relate to a much bigger issue which would probably need to be introduced and discussed separately. Q22A Are the MI, UK and US able to accept the majority view which is to adopt Norway’s proposal as it stands? Yes MI accepts, US, France, UK (cargo ships only) No

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Further Comments / Objections?:France: can also support the proposal. UK: We think that the original text can be retained until we properly discuss in detail the use of “equally” weighted partial indices for passenger ships. Comments received from CLIA/CCSF between round 1 and 2: Regulation 7.1 1. The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, weighted as shown, calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Coordinator’s Comments: CLIA/CSSF have the same opinion as MI. Can they also accept the majority view as asked in Q22A? CG Member’s Comments?:CLIA: Yes, CLIA: Agree. Round 2 Discussion: Nearly all members now accept Norway’s proposals, which will make the first sentence of reg. 7.1 read:An attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, weighted as shown, calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: The UK still opposes these modifications for passenger ships so we will take it to SLF 53 for further discussion. Q22B (for SLF53 WG). Can we accept Norway’s proposed modifications to the opening sentence of reg. 7.1? Yes No Further Comments?:-

A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of

where:

compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1, si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

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Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1 2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below.

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Regulation 7.1 (ref. SLF 52/17/4 Annex C para. 2.1- Norway) 2.1 Amend note EN5 to cover each calculation of A for multiple trims. It is considered that note EN6 could remain unchanged: “5 Three initial loading conditions should be used for calculating each index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. The light service condition will be common for all calculations of index A.” Q23.

Do you agree with the underlined proposed changes to Reg 7.1 EN 5?

Yes

China, Finland, Japan, Norway, Spain, Denmark, Sweden

No

Germany, MI, Italy, UK, US, France [added in Round 2 with comment)

Comments?:China: Propose to replace “mean draught d” with “correspondent draught d” as color text below: “5 Three initial loading conditions should be used for calculating each index A. The loading conditions are defined by their meancorrespondent draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. The light service condition will be common for all calculations of index A.” Germany: Refer to our answer to Q21. CLIA: See CSSF EN for this issue. Italy: Not acceptable because there may be loading conditions corresponding to light service draught with different trims. US: We prefer the original text; this EN is describing the general case. Round 1 Discussion: In view of the complexity of the proposals and the number of comments received, this table has been duplicated in Appendix 1 which contains all the changes proposed by Norway. So please turn to Appendix 1 for continuation of the discussion and the Round 2 questions. This also applies to Q21 and Q25. France: comment added in round 2 response No agreement to add “The light service condition will be common for all calculations of index A.” It may be necessary to calculate attained index with different trim at light service draft to cover the whole draft/trim range of all loading conditions. Round 2 Discussion: With France’s new comments, opinion is quite evenly divided on Norway’s proposal for dealing with the light service condition in the EN (7 in favour, 6 against, with China proposing an alternative). We can continue this discussion under new Appendix 3 which includes further proposals for presenting limiting GM/KG curves/tables to allow for the

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operating trim and all the criteria as an alternative to Norway’s proposal in Appendix 1. See also Q18, 20, 21, 25 and 26. Any further comments?:-

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. Regulation 7.1 (ref. SLF 52/17/4 Annex C para. 2.2- Norway) It is believed that it would be beneficial to provide some guidance as to what extent deviations from the draught and trim in the light service condition may be accepted without performing new calculations. This could be relevant where data for a sister ship in a series is to be used or if the results of an inclining test or lightweight survey differ from the assumed loading case used for partial index Al. The following interpretation is proposed for inclusion as a new note 7: 7 A previously approved partial index Al may be considered to remain valid for a sister ship and in other cases where differences in light ship particulars result in minor deviations from the assumed draught and trim in the light service condition. It is recommended that the limits for validity of stability documentation in case of lightship deviations set out in regulation 5.2 be applied also for this purpose.” Q24. Do you agree with this proposed addition to Reg. 7.1 EN? Yes

China, Finland (with comments), Japan, MI, Norway, Spain (but see comments), Denmark, Sweden, US (but may be confusing as proposed) Germany (with comments), Italy (with comments), UK

No

Comments?:Finland: Into proposed addition also include a reference to changes between PRELIMINARY and FINAL damage stability calculations - not only to sister ships. “.. remain valid for a sister ship and in other cases...”. “Other cases” is too vague to suggest that it could also mean changes between Preliminary and Final calculations. [Co-ordinator’s Note: wording changed slightly from original submission for clarity – hope it is OK as revised, Finland! Wording for explanatory note amendment by Finland would be needed here, if proposal accepted]. Germany: NO support for this paragraph as the deviation is related to “lightship data” only. In our view the deviation must be linked to “lightservice draft/Ballast Arrival” as this can also be subject to changes from PRELIMINARY to FINAL Stability Booklet or within a series of vessels. As a consequence we propose the following definition of acceptable tolerance/deviation for “lightservice draft/Ballast Arrival” - Draft [+1%] of displacement (based on data from “light service draft), i.e. for draughts bigger than initial dl a small tolerance of +1% of light service displacement is acceptable (definition of negative tolerance not needed as a smaller draft would be beneficial for the Al

Index) -

Definition of acceptable trim deviation not needed as in the GERMAN proposal (refer to Q21) dl is considered as a design parameter and trim variations for dl are acceptable (i.e.

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designer has to carry out damage stability calculation that covers the full operational trim over the entire draft range)

Norway: Norwegian paper. We realise that it would perhaps be better to replace the reference to regulation 5.2 with the actual limits. CLIA: CSSF EN work. Italy: Alternative text – “A previously approved partial index Al may be considered to remain valid for a sister ship and in other cases where differences in light ship particulars result in minor deviations from the assumed draught and trim in the light service condition. It is recommended that the limits for validity of stability documentation in case of draught and trim deviations be the following: +/- 1% of displacement at light service draught (dl); +/- 0.5 % of Ls” Spain: Only as a remark. Regulation 5.2 only applies to cargo vessels (“The Administration may allow the inclining test of an individual cargo ship to be dispensed with provided basic stability data are available from the inclining test of a sister ship...”). In line with this assumption, we propose to accept this proposal only for cargo ships. US: We think this proposal may be confusing. However we agree it may be useful to have some discussion as to what extent deviations from the draught and trim in the light service condition may be accepted (given a [single] light service draft condition). Round 1 Discussion: There is considerable general support for the need to make some provision for small changes in dl and corresponding service trim arising, for example, from differences in preliminary and final lightship particulars, a series of new “sister” cargo vessels with minor variations, the growth in lightship of passenger ships as measured by the 5-yearly lightship check or minor modifications to cargo/passenger ships (MSC/Circ.1158 covers these situations, see under Q17, above). The US believes the proposal as it stands may be confusing but is open for dialogue. Spain points out that 5.2 applies only to cargo ships and would only accept an extra EN applied to these ships. Norway now thinks it would be better to include the deviation limits in the EN rather than crossrefer to Reg. 5.2. Germany and Italy have come up with text proposals, including specific limits for dl but Germany does not consider a trim limit necessary; Finland is concerned that “in other cases”, as proposed by Norway is too vague if the intention is also to allow for differences between preliminary and final lightship data in a new or converted ship. Proposed Action: To try to accommodate as many suggestions as possible here is a draft amended version of Norway’s original proposal for further consideration making use of the existing limits and situations from MSC/Circ.1158: 7 A previously approved or preliminary partial index Al may be considered to remain valid where small differences in light ship particulars result in minor deviations from the assumed draught (dl) and actual trim in the light service condition. It is recommended that the limits for determining whether partial index Al remains valid be based on the permitted deviations in displacement and LCG set out in MSC/Circ.1158 for deciding whether or not an inclining test is needed. Q24A Given the wide support for Norway’s proposal but acknowledging that there are several suggestions for alternative texts, would you be able to support the compromise text shown under “Proposed Action” for Reg. 7.1 new EN7? Yes MI, Finland, Italy, Japan, France (with comment), Norway, CLIA (with comment), UK, Sweden, Denmark

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No

Germany (with comment), US (with comment).

Comments / Should this only apply to cargo ships?:MI: Can support compromise text. Germany: No, reference shall be made to light service draft (but not to lightweight) (refer to previous position from GER). France: Situation may be slightly different if comparison is made between a sister ship or between final and provisional calculations. For a sister cargo ship, if difference in lightship is within the given tolerance, the two ships will be considered as identical and stability documents will be identical. In this case, proposed amendment would not be necessary. Final stability document or result of a passenger sister ship will be based on the results of the weighing and inclining test and there is no chance that result will be identical to previous one. Proposed amendment should cover these cases, so it should be also applicable to passenger ships. Practical problem may arise if final lightship (or sister ship in case of a passenger ship) is lighter than previous one. Light service draft may be outside of the draft range. Even for a few centimetres, it would be necessary to extrapolate the required GM curve (Constant GM between calculated dl and actual dl?). CLIA: This should not only apply to cargo ships. US: We do not think reference to MSC/Circ.1158 is appropriate. Possibly use the deviations in reg 5.2 for cargo ships and reg 5.5 for passenger ships. We do not think guidance of this nature regarding reg 7.1 should be restricted only to cargo ships based on reg 5.2. Round 2 Discussion: Although most agree that a new EN is needed there is still not unanimous approval for the wording of Norway’s proposal (or the modified version). The US suggests using reg. 5.2 for the % deviations (as originally proposed by Norway) rather than MSC/Circ.1158 but Norway (and Italy and Germany) think it preferable to use actual deviation limits. The reason for Norway’s original proposal was to try to avoid the extra work needed in recalculating A if dl changes slightly (also affecting dp). For passenger ships, the definition of dl in reg. 2.11 and the accompanying EN does permit some flexibility so that dl could be a declared value agreed with the Administration for use throughout the lifetime of the ship unless major modifications are carried out. Under IMO Res. A265 the MCA had a recent case where a passenger ship fitted some extra accommodation but it was decided that the lightest service draught (do) could remain the same as the increased lightweight could be compensated by reduced ballast and/or consumables in the 10% arrival condition. Even for cargo ships, some flexibility is possible by varying arrival consumables. What is different about S2009 is that under Reg. 7.2 the light service draught is to be used with the actual service trim resulting in much less flexibility and some difficulties in creating limiting KG/GM curves. The methods proposed in Appendix 3 could overcome these problems by removing the fixed service trim (as originally proposed by Germany). With some flexibility already permitted for dl in EN 2.11, it may not then be necessary to say very much in the new EN7. For example:7 For both passenger and cargo ships, the light service draught (dl) as defined in Regulation 2.11 and the accompanying Explanatory Notes may be assumed to remain valid unless the ship undergoes lengthening or other modification to the external hull resulting in changes in the stability characteristics. 7 A previously approved or preliminary partial index Al may be considered to remain valid where small differences in light ship particulars result in minor deviations from the assumed draught (dl) and actual trim in the light service condition. It is recommended that the limits for determining whether partial index Al remains valid be based on the permitted deviations in displacement and LCG set out in MSC/Circ.1158 for deciding whether or not an inclining test is needed.

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Q24B (for SLF 53 WG). If we can overcome the problem of the fixed service trim in reg. 7.2 (as proposed in Appendix 3 for example), can we agree to adding a simplified new EN 7, as proposed under round 2 discussion, above? Yes No Further Comments/ proposals?:-

[2

In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of [Ls] [L], one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of [Ls] [L]. ] -----------------------------Regulation 7.2 (ref. SLF 51/3/2 Annex – US and Sweden) The treatment of trim in the damage stability calculations is an item that has been identified for further consideration (this item is also related to the stability information required under regulation 5-1). At SLF 49, Norway made an oral proposal leading to extensive discussions regarding GM limiting curves for different trims (see figure/proposal below). There was extensive support for the proposal but it was dropped for not being exactly in line/allowed by the wording of the last sentence in regulation 5-1.4 (see proposed revision to regulation 51.4 above to allow this). This issue and proposal should be revisited.

Trims used in calculations

Related comments from the United Kingdom: We have seen examples in stability information booklets based on the current regulations where only level trim minimum GM curves are shown. The booklet then shows a loading condition where the vessel has some stern trim and seems to comply with the minimum GM curve and yet if the trim is taken off by shifting a load horizontally, the condition would not comply. The reason is that KM generally increases as the ship trims by the stern and so therefore does GM, while KG remains fixed. Some yards/owners take advantage of this effect and it can

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lead to discrepancies with the onboard stability computer. We can envisage a similar loophole being exploited in the SOLAS 2009 regulations where regulation 5-1.3 requires trimmed information only if the operational trim range exceeds +/- 0.5% of Ls. For these reasons we would like to suggest that only maximum allowable KG curves/tables be used. We propose a further simplification for presenting the limiting KG curves to make them easier to read (see figure below). It can be seen that calculations for 9 points are required encompassing the entire range of draught and trim. The curves are derived by linear interpolation between trims for each of the 3 draughts and compliance can easily be checked by spotting on the trim and KG from the loading condition and interpolating the critical KG curve at the actual draught. Any restrictions in trim at a particular draught can also be shown easily by simple use of shading to indicate prohibited ranges of operation. Critical KG‘s can also arise from regulation 8 (minor damage), regulation 9 (bottom damage) and may arise from the new stability criteria to be introduced into regulation 8-1 (return to port). Intact stability could also influence the critical KG curves. All of these extra curves could be incorporated into this simple diagram with the worst critical KG at each draught/trim combination being plotted but still with only 3 limiting curves for the master to use.

In our experience, particularly with ro-ro passenger ships, the influence of trim can become important at much lower %Ls values. Our proposed method of plotting limiting KG against trim for the three calculated draughts at three trims would therefore always be applied to every ship, regardless of the size of the operational trim range (on the basis that all ships have some trim at some time). -----------------------------Regulation 7.2 (ref. SLF 52/17/6 - Norway) Replace Ls with load line length (L) for consistency (see Regulation 2.9 and 2.13 for details). -----------------------------[Coordinator’s Note: Norway now proposes to replace the whole of Regulation 7.2, see below. Please refer to Q25, which covers all the following proposed changes.]

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Regulation 7.2 (ref. SLF 52/17/4 Annex A para. 2.2 - Norway) In 7.2 replace the current text to cover principles discussed above [under Regulations 51.3 and 5-1.4]. The word “actual” could be replaced with “anticipated” to provide some flexibility if the trim in the final stability calculations deviates from preliminary results due to variations in the lightship particulars: 2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The [actual] [anticipated] service trim shall be used for the light service draught dl. If in any anticipated service condition within the draught range from ds to dp the trim variation in comparison with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of A are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. The partial index Al is considered constant for the purpose of these calculations. -----------------------------Regulation 7.2 1. The calculations for differing trim should be carried out with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). Regulation 7.2 (ref. SLF 52/17/4 Annex C para. 3- Norway) 3.1 Note 1 does not correspond with the principles in 5-1.4 regarding trims. Note 1 and 2 will in any case become redundant and could be deleted if the regulations are amended as proposed in Annex A of SLF 52/17/4. 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1.

3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) (ref. SLF 52/17/4 Annex C para. 1 - Norway) 1.2 The following is transferred from 7.2, note 3 [to 5-1] and amended where underlined:3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls. 1.3

Move the sketch from 7.2, note 3 accordingly.

Regulation 7.2 (ref. SLF 52/17/4 Annex C para. 3- Norway) 3.2 It is proposed to move the contents of note 3 regarding design of limit curves to 5-1.4 or delete it as redundant. Q25. Norway proposes to replace the existing text of Reg 7.2 and re-organize and re-number the remaining regulations and EN in association with Reg 5-1.4 (see Appendix 1 for complete version). It is assumed that these amendments are intended to replace Norway’s earlier proposals in SLF 51/3/2. An alternative proposal from the UK in 51/3/2 suggests that maximum allowable KG’s rather than minimum GM’s should be used and that the limiting curves should be presented as a variation against trim for the 3 specified draughts (assuming linear interpolation between draughts). Combined critical KG curves would then cover all the relevant stability criteria, both intact and damage. No specific changes to the text of the Regulations or EN were proposed. As this is a fairly complex issue we would simply like to ask if there is support at this stage for Norway’s package of proposals for Reg 7 as shown in Appendix 1; are there any objections, questions or alternative proposals?

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Yes (Accept Norwegian proposals in App 1)

China, Finland, Germany, MI (but see comments), Norway, Italy, US

Japan, Spain (see comments), Denmark, UK, Sweden No Comments, reasons, alternative proposals?:Finland: Support Norway. No support for UK proposal. Prefer GM-limiting rather than KGlimiting curves. Germany: Support Norway’s proposal (strong objections against UK proposal!) Japan: It is not clear how to deal the case that the trim in the loading case between Dp and Dl exceeds the range of calculated trim. MI: Could support Norway’s proposals because they are in a package but the UK suggestion of using max allowable KGs and resulting combined critical KG curves has considerable merit and should be further discussed before a final decision is made. CLIA: CSSF EN work. Italy: See also comments on item 21. Spain: We accept the proposals except the trim versus draught graph. As we have explained, it is not very clear in our opinion. We have made one proposal: -

To change the axis (e.g. draught X axis and trim Y axis):

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Spain (continued): Regarding UK proposal, we think it is more clear than the other proposed trim limit curve (we can accept it), but we think that for the master is more intuitive to have GM or KG curves versus draught (and different curves depending on trim), e.g.: Max Allowable KG vs Draught Trim Aft

Trim 0

Trim Fwd

8.5 8

Critical KG (m.)

7.5 7 6.5 6 5.5 5 4.5 4 4

4.5

5

5.5

6

6.5

7

Draught (m.)

End of Spain’s Proposals Denmark: We wonder if it is worth considering whether the trim limits should be restricted to no greater than the calculated conditions, as it is for deterministic damage stability. Consider that if the partial indices are at 0.5R or 0.9R for a particular trim, allowing 0.5%L more trim will most certainly reduce the attained partial indices. US: We support in principle; details subject to further consideration. Round 1 Discussion: In view of the complexity of the proposals and the number of comments received, this table has been duplicated in Appendix 1 which contains all the changes proposed by Norway. So please turn to Appendix 1 for continuation of the discussion and the Round 2 questions. This also applies to Q21 and Q23. Round 2 Discussion: Please see new discussions which are now appended to Appendix 3.

New Paragraph 7.3 (ref. SLF 52/17/4 Annex A para. 2.3 - Norway) Add a new paragraph 7.3 for emphasis: 3 Each additional value of A calculated in accordance with paragraph 2 shall comply with regulation 6 and 7.1 Q26. Yes No

Do you agree that this new paragraph should be added? China, Finland, Germany, Japan, Norway, CLIA, Italy, Spain, Denmark, UK, US, Sweden MI

Comments?:US: Note: this provision could be added directly to regulation 7.2. Round 1 Discussion: There is almost unanimous support for this proposal (12/1) but US suggests that it could be added to Reg. 7.2. This would avoid having to re-number the remaining paragraphs and any possible cross-referencing problems but it might lose some impact; also it would need re-wording slightly:3 Each additional value of A calculated in accordance with [paragraph 2] [these provisions] shall comply with regulation 6 and 7.1

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Q26A Given the wide support for Norway’s proposal but acknowledging the US suggestion that the sentence could instead be added to Reg. 7.2 could you please state your preference? New 7.3 France (with comment), CLIA Add to 7.2

MI, Germany, Finland, Italy, Japan, Norway (with comment), UK, US (with comment), Sweden, Denmark

Comments?:MI: Accept as addition to 7.2. France: This additional sentence seems to be obvious considering regulation 6. Norway: We can both support the US suggestion or a new 7.3 as originally proposed. US: Note: the original Norway proposal was “... comply with regulation 6.1 and 7.1.” Round 2 Discussion: Apologies. Norway’s proposal was indeed referring to reg. 6.1 Thank you US. So if we add this sentence to reg. 7.2, as the majority agree, then it should read:

[2

In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of [Ls] [L], one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of [Ls] [L]. Each additional value of A calculated in accordance with [paragraph 2] [these provisions] shall comply with regulation 6.1 and 7.1 ]. Proposed Action: As we do not have a unanimous view on whether to append the sentence to reg. 7.2 or add a new reg. 7.3 and in view of the concerns elsewhere regarding interpolation between dl and dp, it is proposed that this discussion be continued in the wider context of an alternative proposal (see Appendix 3) which would change this paragraph considerably. Further Comments?:-

[Co-ordinators Note: If new paragraph 7.3 is preferred then the subsequent paragraphs and EN shown in blue below will have to be re-numbered.] 3 When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding, [Q27B] the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. [Post SLF 53 note:- It was decided in the WG to add “in the final stage of flooding”, as highlighted in red, above (see also Reg. 7.6, Q27) but not to include a further clarifying sentence at the end saying “During intermediate stages of flooding the added weight method should be used”. However, it was agreed to include a new EN at this point. For origin of this text see discussions under Reg. 7.6, Q27, below]:Regulation 7.3 “The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full

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phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.” [Further Note from the coordinators post SLF 53:- Maybe we need to consider changing the first sentence of the new EN slightly to introduce the idea that residual GZ is to be calculated for both IS and final stage flooding where appropriate eg:“In some damage scenarios it is possible that the residual GZ curve will reach its minimum value during intermediate stages or phases of flooding rather than at the final stage. In these cases, during intermediate etc etc…………. Your comments on this proposed change are invited under Q27B, below. After further discussions in the 2011 CG the following text changes were voted upon:Regulation 7.3 During For intermediate phases of flooding (see Reg. 7-2.2 with Explanatory Notes and Reg. 7-2.5.4), [Q27D(1)- 11-0 unanimous vote in favour of change]the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the [lost buoyancy] [constant displacement] method is used, so one free surface is assumed for all flooded spaces. [In both cases, GZ is referred to the intact displacement]. [Q27D(2)] [Should we allow for multiple free surfaces - opinion divided 5 “Yes” 6 “No.”] [Q27D(3)]

4 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 5 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only [to the centreline] to one half of the ship breadth B and ignore changes in subdivision that would reflect lesser contributions.

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R7.5 EN (Difference between B/2 and centreline) Comments received from CLIA/CCSF between round 1 and 2: The EN refer to the centreline of the ship rather than to B/2 for the transverse extent of the damage: With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only to the centreline to one half of the ship breadth B and ignore changes in subdivision that would reflect lesser contributions. Coordinator’s Comments: It would seem that the proposal by CLIA/CSSF better reflects the wording in the Regulation – but what is the difference between the centreline and B/2? CG Member’s Comments?:MI: Can agree CLIA proposal which provides more consistent wording. Germany: At the ends of the vessel B/2 line crosses the CL, so that a different penetration depth is achieved. France: Agreement on the proposal. B/2 is different from centreline where deepest waterline is not at B/2 from centreline. Norway: Agree with CLIA, but the following might be clearer: “It is not correct to assume only a damage penetration equal to one half of the ship breadth B and ignore lesser penetrations that would reflect lesser contributions.” CLIA: B/2 may create damages beyond the CL, where the waterline has not the full breadth anymore (e.g. Forward end). UK: No need to change “centreline” reference. US: We can accept this proposed change. Round 2 Discussion: There is some support for CLIA’s proposal (apart from UK); Norway has an alternative. We propose that this should go to the WG at SLF 53 to obtain further opinion and views on Norway’s proposal. CLIA Q2 (for SLF53 WG). Do we prefer CLIA’s proposal or Norway’s amendment or no changes? CLIA? Norway ? No change? Comments?:The WG at SLF 53 accepted CLIA’s proposal. CLIA Q2 RECOMMEND ACCEPTANCE OF TEXT CHANGE AT SLF 54 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads.

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6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed [in the final stage of flooding]. [Coordinator’s Note: see SLF 52/17/5, below, Q27. Change in red accepted by WG at SLF 53]. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. [Should anything be added here on multiple free surfaces?] [Q27D(3) see Reg 7.3 EN] Regulation 7.6 (ref. SLF 51/3/2 Annex – US and Sweden) The assumption/simplification that “only one free surface need be assumed” in the flooding calculations should be reconsidered. -----------------However, associated with including this item for future reconsideration were several additional concerns as follows: a.

If the use of multiple free surfaces were to be adapted in the future, then the basis for how the R-index was developed would also have to be reconsidered. What would the GM requirement level for SOLAS 90 ships be if instead of one free surface, multiple free surfaces were applied?

b.

It has been assumed in the SOLAS 2009 regulations some generally approved simplifications. This seems to be in line with the whole harmonization work; i.e. what has been done over the last 15 years. To account for multiple free surfaces is quite a complicated matter. For example in the cabin area the space has been considered as one room. Because the space is extending from side to side the effect of multiple free surfaces is very large in the calculations. But in reality there are cabin blocks, which certainly will change the calculated value. -----------------Regulation 7.6 (ref. SLF 52/17/5 Annex - Norway) Document SLF 51/3/2 contains a proposal that the assumption/simplification “only one free surface need be assumed” in the flooding calculations should be reconsidered. This Administration agrees with this view. In particular, the current text conflicts with calculations of intermediate stages of flooding. As a minimum, the regulation text should be amended to read: 6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed in the final stage of flooding. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. R7.3 & 7.6 and new EN for R7.3 Q27. Taking into account points a and b in SLF 51/3/2 (above), do you agree with Norway’s proposal to amend Reg 7.6 as shown in the underlined text or is more consideration of this issue needed before such a change can be made? Yes

(accept Norway’s addition to the existing text): China, Finland, Norway, Spain, UK

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No

(do not accept Norway’s addition to the existing text): Germany, Italy, Denmark

Comments / More consideration needed / Alternatives / Proposals?:Finland: Final stage is acceptable to have only one free surface. Method how to notice free surfaces during intermediate stages and phases to be also clearly defined. This may require further studies. If damage is considered to have a very large number of intermediate stages the stability curve of the last intermediate stage must be practically the same as the stability curve of the final stage (calculated with the lost buoyancy method) since in reality the flooding is a continuous process. Also the spirit of the rule concerning the damage extents should not be violated. Germany: Final stage OK, but the method how free surfaces are to be applied for intermediate stages has to be defined clearly. Japan: Our proposal: “multiple free surfaces may be assumed in the intermediate stage of flooding.” should be inserted in either regulation text or EN. MI: Matter requires further consideration. CLIA: More consideration. Spain: The use of multiple free surfaces is more correct from a physical point of view, but we agree with your opinion, to account for multiple free surfaces is quite a complicated matter, and we think that it is for future reconsideration. Any modification in relation to this matter should me made jointly with software suppliers and with the ship designers. Denmark: Some research showing the implications and feasibility of this amendment should be undertaken before making a decision. US: We believe more consideration of this complex issue is needed. Sweden: More consideration needed. Round 1 Discussion: There is considerable hesitation and concern expressed by members over the important issue of multiple free surfaces (MFS). However, it seems hard to argue against Norway’s statement in SLF 52/17/5 that:“In particular, the current text conflicts with calculations of intermediate stages of flooding”. At the Malmo inter-sessional meeting in December 2003, there was discussion around the issue of including a probabilistic “s” factor to account for transient asymmetrical flooding, which can lead to the vessel capsizing before the equalisation process has time to commence. Rapid loss arising from the formation of MFS on vessels with multiple decks below and just above the waterline has also been observed in model tests. These phenomena were finally omitted from the harmonisation regulations as the brief was to ensure that S2009 gave rise to an equivalent level of safety to the then current regulations (S90), which did not allow for them so they were flagged up for possible later inclusion under the heading of “future developments”. This raises the question of whether we are still bound by the “equivalence to S90” requirement or can we now, if there is shown to be a compelling need, increase the safety level provided by S2009 in certain areas (such as allowing for MFS)? Is it possible to do this without re-calculating “A” for many S90 ships allowing for MFS, for example, then revising the “R” index accordingly – a long and expensive process? Or can we retain the same “R” index but simply ask for MFS to be accounted for during intermediate stages of flooding, as proposed by Norway?

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There is also an issue of complexity, touched on by several members – it would be quite difficult to ensure a rational approach to the calculation of multiple free surfaces during intermediate stages of flooding in complex “rooms” without employing time-based flooding simulations, which are not widely available. On the other hand, as Norway suggests, intermediate stage flooding calculations are somehow being undertaken at the present time for new S2009 designs (although there are rumours that they are being overlooked in some cases as being “too complex”, which may be due to lack of clarity/guidance in the Regs and EN). In this respect, Finland’s comment hinting that intermediate stages are being calculated using an added weight, rather than a lost buoyancy method is intriguing. Is this the commonly accepted practice? Older software packages used to determine the final equilibrium situation having first allowed users to nominate the number of stages with the % filling depth for each stage in the affected rooms. The software would then divide the total weight of floodwater at final equilibrium in each room by the number of stages and work out the damage stability accordingly at each stage (all based on lost buoyancy). The aim was to find if there was a risk of capsize at any time during the intermediate flooding sequence, but the choice of filling depths in each progressively-flooded room was largely a matter of “judgment” (i.e. guesswork!) and it was possible to miss the worst combination altogether. Perhaps it is more valid to calculate residual stability using lost buoyancy only for those compartments breached and directly open to the sea and added weight for those which are progressively flooded? Your thoughts on using added weight during IS flooding would be welcome. It therefore seems clear that if we do agree to Norway’s proposal (5 members in favour), some further explanation of the treatment of multiple free surfaces during intermediate stage flooding may be needed in the text and/or the EN, as suggested by Japan. Also, as suggested by Finland, the wording of the regulation may need to be changed slightly to accommodate Norway’s proposal so as to avoid a misunderstanding that only one breach of the hull is to be considered in the final stage of flooding [implying that many breaches are to be considered during other stages]. Proposed clarification:6 In the flooding calculations carried out according to the regulations, only one breach of the hull [is to be considered] and only one free surface need[s] to be assumed in the final stage of flooding. Proposed Alternative Actions:Either (1) We report to the SLF sub-committee that we have considered Norway’s proposed amendment to Reg 7.6 in SLF 52/17/5 regarding MFS but have concluded that this issue, although urgently in need of attention, first needs more research into finding out how best to make allowance for it within the Regulations and EN. Or (2) We acknowledge the risk of ignoring the possibility of MFS any further and accept Norway’s proposal [amended as shown?] then attempt to include some new regulatory text (and/or EN) on the treatment of MFS during intermediate stage flooding, based on current best practice. Q27A. Please indicate which alternative you prefer:Yes to Alt (1) Yes to Alt (2)

MI, Japan, CLIA (with comment), UK, Sweden Germany, Finland, Italy (with comments), France (with comments), Norway (with comment), US (with comments), Denmark

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Please also note that Germany and Finland raise the issue of using the added weight method during intermediate stages of flooding in their response to Q35. [Coordinator’s Note: Inserted here for easy reference .. Finland: Method how to notice free surfaces during intermediate stages and phases to be also clearly defined. This may require further studies. If damage is considered to have a very large number of intermediate stages the stability curve of the last intermediate stage must be practically the same as the stability curve of the final stage (calculated with the lost buoyancy method) since in reality the flooding is a continuous process. Also the spirit of the rule concerning the damage extents should not be violated. Germany: Intermediate phases have to be calculated by “added weight” method.] Comments / Other Alternatives / If Alt (2) is chosen do you support the proposed clarification?:Italy: We support the proposed clarification, but only in conjunction with the clarification submitted by CLIA/CSSF on the intermediate filling phases with the “added weight” method [Coordinator’s Note: see under CLIA, below.] RINA: If multiple free surfaces can occur from a single breach, in either the intermediate or final stages of flooding, then the loss of GM from each free surface will have a cumulative effect and must be considered. This is particularly important when a ship is being operated based on data from the limiting GM/KG and the operational limit is close to the GM/KG envelope. It is noted that intact stability takes into account multiple free surfaces. France: The question is related to intermediate phases which are treated with added weight method. From our understanding, the meaning is that only one free surface is considered for all spaces flooded in the same stage. At the end of each stage, filling level in flooded compartments reach the outside water level, so one free surface is observed. More precise wording would be : “During intermediate phases of flooding, added weight method is used and only one free surface need to be assumed for water in spaces flooded during the current stage. In final phase (full phase) of each stage lost buoyancy method is used, so one free surface is assumed for all flooded spaces.” Norway: Supports proposed clarifications. Please also see answer to Q35A. [Coordinator’s Note: Inserted here for easy reference – “Using constant displacement in this context where no initial masses are considered lost (as opposed to cargo in MARPOL etc) will normally be slightly conservative with respect to the effect on the righting lever. We are not sure if the wording in regulation 7.3 was included for this reason. Please note that our proposal and MSC/Circ.406/rev.1 relates to the “final survival conditions”. We agree that the question on whether to disregard the transient added mass in partially flooded spaces not communicating directly with the sea as well as handling of free surface effects in these spaces should be discussed further.”] CLIA: See CLIA/ CSSF comments to reg. 7-2.2 EN3 which supports added weight method for intermediate phases, resulting in more than one free surface. [Coordinator’s Note: inserted here for easy reference:3. For each damage scenario, the damage extent and location determine the initial stage of flooding. Calculations should be performed in stages, each stage comprising of at least two intermediate filling phases in addition to the full phase per flooded space. Unrestricted spaces in way of damage should be considered as flooded immediately. Every subsequent stage involves all connected spaces being flooded simultaneously until an impermeable boundary or final equilibrium is reached. If due to the configuration of the subdivision in the ship it is expected that other intermediate stages of flooding are more onerous, then those should be investigated Additional explanation: The purpose of calculation of sequential flooding is to ensure that any intermediate

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flooding stage or phase will not lead to a lower si value. The calculation of the intermediate filling phases should be carried out using the “added weight” method, resulting in more than one free surface.

Spaces flooded during intermediate flooding phase

] US: Generally yes; however, we believe Japan’s proposal to explicitly indicate ‘multiple free surfaces may be assumed in the intermediate stage of flooding’ has merit. Note Regarding the discussion (and general issue) of maintaining an equivalent level of safety to the S90 regulations: It is our view that SLF is no longer bound by the original harmonization “equivalence to S90” requirement (and we should stop interjecting the “re-calculation of S90 sample ships to revise the R index” issue into our current work). May be this issue should be specially addressed and concluded? Round 2 Discussion: There are several issues arising from the question of allowing for MFS. 1) As it was not covered by the previous SOLAS regulations, implementing new MFS regulations within S2009 would mean that the “equivalent level of safety” principle no longer applies. The US raises this point and we therefore propose to seek confirmation from the S-C that we are no longer bound by the “equivalence to SOLAS90” constraint (ref. SLF 53/14 paragraph 13.1). 2) There was a small majority (7-5) in favour of early implementation of Norway’s proposed amendment as opposed to conducting further research first. 3) If we accept the majority view we could change reg. 7.6 as proposed by Norway and as amended slightly to:“6 In the flooding calculations carried out according to the regulations, only one breach of the hull [is to be considered] and only one free surface need[s] to be assumed in the final stage of flooding.” 4)

There is a proposal by Japan, supported by the US, to add further clarification:-

“6 In the flooding calculations carried out according to the regulations, only one breach of the hull [is to be considered] and only one free surface need[s] to be assumed in the final stage of flooding. [Multiple free surfaces may be assumed in the intermediate stage of flooding.]”

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5) It seems that there is general agreement that the added weight method should be used during intermediate stages. This may mean we will also need to consider altering reg. 7.3 (see also Norway’s proposals under Q35):“3 When determining the positive righting lever (GZ) of the residual stability curve [in the final stage of flooding], the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used [During intermediate stages of flooding the added weight method should be used ].” 6) The question then arises as to the need for a new EN for reg. 7.6 (and/or 7.3). As a starting point, we suggest that France’s submission could be used for this purpose, maybe beginning with CLIA’s to the EN for reg 7-2.2 (EN3):“The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy[constant displacement] method is used, so one free surface is assumed for all flooded spaces.” Proposed Actions:1) Raise the general issue of equivalence between S2009 and previous SOLAS regulations in plenary for a decision from the S-C. 2) In the WG discuss the question of either (a) doing further research or (b) trying to change regulations [7.3 and] 7.6 and the EN now. 3) If (b), discuss the above changes to reg. 7.3, 7.6 and the EN and report back to plenary. Q27B (for SLF 53 S-C). 1) If we believe we have uncovered safety deficiencies in SOLAS 2009 are we now free to propose improvements without being constrained by the requirement to maintain an equivalent level of safety to the previous SOLAS regulations? (for SLF 53 WG) 2a) Do we wish to delay amending reg. [7.3 and] 7.6 and accompanying EN to allow for the effect of multiple free surfaces until further research is carried out? OR, 2b) Do we wish to change reg. [7.3 and] 7.6 as soon as possible? 3) If 2b) Can we accept any of the proposed changes to reg. 7.3 and 7.6 and EN, made under the round 2 discussion above? Q1 (Y/N)? Post SLF 53 note:- “The Sub-Committee agreed that it was no longer bound to maintain an equivalent level of safety to the previous SOLAS chapter II-1 subdivision and damage regulations and that this new output is aimed at refining and improving the current SOLAS chapter II1, based on experience gained in the application of its provisions. If the current work uncovers safety deficiencies in the chapter then they should be corrected”. (Ref. SLF 53/WP.1 paragraph 14.5). Q2 Prefer The WG at SLF 53 decided to accept Norway’s original proposal 2(a) or without any changes, as shown highlighted in red, above. 2(b)?

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Q3 If 2(b), state preferred wording (or alternative)?

Similar changes were agreed by the WG at SLF 53 to Reg. 7.3 in association with a new EN based on Round 2 discussion point 6), above. As the WG did not agree to include the proposed sentence relating to IS flooding, the coordinators now believe that the opening sentence of the proposed new EN for Reg 7.3 should be changed slightly to read:“In some damage scenarios it is possible that the residual GZ curve will reach its minimum value during intermediate stages or phases of flooding rather than at the final stage. In these cases, during intermediate etc etc…………. The currently agreed text for the EN for Reg. 7.3 reads:“[The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value]. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.”

Q27C (for Round 4 questionnaire). Would you agree to replacing the opening sentence in the EN for Reg. 7.3 (shown in square brackets with strikethrough, above) with the text in green as proposed under Q3 above?:Vanuatu, US, Sweden, Norway, Japan, China, RINA, Denmark, Italy, UK, Yes Spain, EC (however, ongoing research (GOALDS and EMSA 2) might have a bearing on this. Results of these studies should be taken into account), CLIA (this seems to explain it better. No objection), MI (agree the revised opening sentence provides greater clarity). Germany, Finland, France No Further Comments?:Germany: The wording shown above in red/grey should be kept, also keep the first sentence in the square brackets. Finland: The text shown above in red/grey should be kept, and also first sentence “The purpose of calculation …” to be kept. See also our comments for Q27. France: Survival factors are calculated with different formula for intermediate or final stages of flooding, so it should not be made reference to GZ curve to compare these stages. The purpose of regulation 7.3 is to determine the way of calculation of the GZ curve, for intermediate or final stages of flooding, so it should be sufficient to write : During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces. In both cases, GZ is referred to the intact displacement.” Round 6 Discussion: There is a clear majority (14 – 3) in support of the proposed changes (summarized below, for easy reference):2

When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding, the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used.

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Regulation 7.3 “[The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value]. In some damage scenarios it is possible that the residual GZ curve will reach its minimum value during intermediate stages or phases of flooding rather than at the final stage. In these cases, Dduring intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.” In response to comments from Finland, France and Germany, the red text in italics highlighted in grey was agreed by the WG at SLF 53. The strikethrough and the text highlighted in green was proposed by the co-ordinators in round 4 as the sentence “The purpose of calculation of sequential flooding etc” suddenly appears in an EN supposed to be clarifying a regulation which now refers (in its altered form) only to the final stage of flooding. The sentence would have been more appropriate if the regulation itself had mentioned IS flooding, as was originally proposed, but this was not agreed to by the WG. Also, those reading revised reg. 7.3 will immediately wonder what the SOLAS requirements are for the other stages of flooding, which is why the new EN appears here with the introductory sentence in green. Another reason for deleting the sentence beginning “The purpose of calculation … etc” was that it does not seem to add any further explanation to existing Reg. 7-2.2 concerning calculation of the least of the s-factors from all flooding stages. The existing EN (3) for reg. 7-2.2 already contains specific guidance on the computation of IS flooding - the only thing not specified is the use of the added weight method. When we proposed the additional sentence in green (above) we had not made the connection with EN (3) for reg. 7-2.2. So, to avoid duplication, we now think it may be better to link the new EN for reg. 7.3 to reg. 7-2.2 and 7-2.5.4 as shown below (more or less as France suggests except for the changes highlighted in green):Regulation 7.3 During For intermediate phases of flooding (see Reg. 7-2.2 with Explanatory Notes and Reg. 7-2.5.4), the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces. [In both cases, GZ is referred to the intact displacement]. As we now understand it, the standard practice is to use the added weight method for intermediate stages of flooding and the lost buoyancy method in the final stage of flooding. We wanted the regulations and EN to reflect this practice, so we hope you can now agree to the above changes. We are sorry for changing things around again. We are not 100% sure that the last sentence in square brackets above, proposed by France, is correct as we had thought it may be more logical to base the GZ for intermediate flooding on the (intact displacement + added weight). Perhaps this is too difficult for software to handle (?) but it would give a more conservative result. We invite your opinion in Q27D(2), below. Another issue, which is more relevant to reg. 7.6, and is not directly related to IS

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flooding is that certain model tests have shown that a multi-deck vessel with several horizontal watertight boundaries below and/or just above the waterline could, when suffering a single breach of the hull, very quickly accumulate large free surface moments on several decks simultaneously with potentially very dangerous consequences. The fact that we are now no longer bound to maintain an equivalent level of safety to S90 leaves us free to consider whether this possibility should be allowed for in reg. 7.6 by, for example, removing the phrase “and only one free surface” and perhaps adding a new EN. The calculation of this phenomenon may be difficult, however, involving a water-on-deck approach. So, again, your opinions are invited in Q27D(3), below. Please note earlier discussions in large working document. Q27D (for Round 6 Questionnaire). 1) Do you agree to the new proposal for the EN to reg. 7.3 referring to reg. 7-2.2 etc, as shown in the discussion above? 2) Do you agree that we should add the last sentence in square brackets, as proposed by France? 3) In reg. 7.6, do you think any action is needed to account for the possibility of multiple free surfaces, as outlined in the last paragraph of the discussion? Q1 (Y/N)? Yes: Japan, RINA, Finland, Norway, Germany, US, Italy, UK, France, Denmark, China No Comments: CLIA Q2 (Y/N)? Yes: Japan, Poland, France, Denmark, UK (can we modify the suggested text to “in both cases, GZ curve is calculated with the vessel’s intact displacement”?). No: RINA (We concur with the coordinators comments), Finland, Norway, Germany (No, the square brackets are not needed and may only add more confusion.), US (No – do not add), Italy, China No Comments: CLIA Q3 (Y/N)?

Yes: RINA, Norway, Poland, UK (In principle “yes” to indicate that multiple free surfaces may be assumed in the intermediate stages of flooding), EC (Yes, it seems appropriate to take account of multiple free surfaces, thereby fully taking into account ' water on deck'.) . No: Japan, Italy, Finland, China, Denmark (not at this stage), US (It is our understanding that the current agreed to text for reg 7.6 now indicates “...only one free surface need to be assumed in the final stage.” Under the circumstances it seems this maybe sufficient for the regulation text (i.e. now allows consideration of multiple free surfaces in the intermediate stages but without an explicit requirement to consider them). Then guidance on when multiple free surfaces should be considered could be added to the EN. (so our response is no)). No Comments: CLIA

Further Comments?:Norway on 2): The coordinators’ comment with regard to problems for software to calculate could be relevant. However, it should be possible. RINA on 3): We would agree with the correspondence coordinators comments with regards to paragraph 7.6. It would appear that there are several options that could be considered for the assessment of water which could be entrapped in spaces above the final damaged water and accumulate large free surface moments with the consequential impact on the damage stability of the ship. 1. Apply the requirements for water on Ro-Ro decks in accordance with SOLAS/CONF.3 Resolutions of the Conference of Contracting Governments to the International

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Convention for the Safety of Life at Sea, 1974 - (November 1995) - Resolution 14 Regional agreements on specific stability requirements for ro-ro passenger ships (Adopted on 29 November 1995). 2. Wait for the results of the research projects. 3. Demonstrate compliance with an administrations requirement. Finland on 3): By applying multiple free surfaces there will be inconsistencies between different individual designs. How to define spaces in watertight compartment? During transient flooding (during first seconds) multiple free surfaces have effect. But how realistic are model test results? Has the movements of striking vessels studied during the first seconds? Germany on 3): The consistent application of multiple free surfaces may be very difficult and depends very much on individual designs. Multiple free surfaces as seen during model tests usually appear only during the first seconds of flooding, which are in any way very unclear (e.g. which influence has the striking vessel) Poland on 3): Action is needed to account for the possibility of multiple free surfaces. France on 3): According to proposed wording, two free surfaces may be taken into account during intermediate phases of flooding. If more than two free surfaces have to be considered, this would induce the consideration of too many possible flooding sequences, so it would not be possible to remain within the present simplified approach. This should be dealt with flooding simulation approach, taking into account actual process of flooding water. Phenomenon of accumulation of water on deck (water level in flooded compartment above sea level) should be taken into account in the formulation of survival factor. China on 3): The influence caused by multiple free surfaces may need to be further considered, but it may be also very difficult for software to handle. Q27 For R7.3 and new EN the text change in red was agreed at SLF 53 and there was a unanimous vote of 11-0 in favour of the green text below (Q27D(1)). There was a wide range of views on Q27D(2) and (3), however, so these issues must be discussed at SLF 54 (see also R7.6). 3 When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding, [Q27B] the displacement used should be that of the intact condition. That is, the constant -displacement method of calculation should be used. Regulation 7.3 During For intermediate phases of flooding (see Reg. 7-2.2 with Explanatory Notes and Reg. 7-2.5.4), [Q27D(1)- 11-0 unanimous vote in favour of change]the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the [lost buoyancy] [constant displacement] method is used, so one free surface is assumed for all flooded spaces. [In both cases, GZ is referred to the intact displacement]. [Q27D(2)] [Should we allow for multiple free surfaces - opinion divided 5 “Yes” 6 “No.”] [Q27D(3)] DISCUSS AT SLF 54

7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may

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permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck.

Coordinator’s Note post SLF 53:- The above addition to the text was agreed after some discussion at the SLF 53 WG (see CLIA Q3, below) Regulation 7.7 EN 1 (Stiffeners may be small relative to pipes or valves) Comments received from CLIA/CCSF between round 1 and 2: CLIA Q3 Modification with regard to location of separation valves at watertight bulkheads and decks. Application in practice has shown that the size of the stiffeners might sometimes be too small for large pipe diameters. “Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated within the distance defined above and as close practicable to the bulkhead, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead.” . Coordinator’s Comments: If this is acceptable we would suggest using “in size the depth” instead of “due to their size the order” in the last sentence:Valves which are situated within the distance defined above and as close as practicable to the bulkhead, but exceeding in size the depth of the stiffening structure should still be assumed to be part of the bulkhead.” CG Member’s Comments?:MI: Could agree to the co-ordinators revised text. Germany: Acceptable. Finland: Support. Italy: The proposal is supported. Norway: It is perhaps a better option to handle such large diameter pipes and long spool pieces/valves as recesses, i.e. the zone limits are to be moved away from the bulkhead. CLIA: Agree. US: We can accept this proposed change. Text suggestions: (1) delete the words within the distance defined above and because they are not (or we wouldn’t need this caveat). (2) add “or deck” after bulkhead to cover both.

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Round 2 Discussion: We must point out that similar EN’s appear in two other places (reg. 71.1.1 EN 7 and reg. 7-1.1.2 EN 12). Also note that reg.7-1.1.1 EN 8 would support Norway’s position. For consistency we would either need to consider possible changes to all three EN’s or simply to leave all three as they are. CLIA Q3 (for SLF53 WG). Given that we have other EN’s covering the issues raised by CLIA do you think we should look at revising all three EN’s or should we leave them all alone? Revise all 3 EN’s? Leave all 3 EN’s alone? Further Comments?:Post SLF 53 comments:- The WG at SLF 53 amended each of the EN’s as appropriate (see changes highlighted in grey). CLIA Q3 [Coordinator’s Note:. There is a new proposal to harmonize the text with reg. 7-1.1.1 EN7 and reg. 7-1.1.2 EN 12, as highlighted in green, below. For full discussion see reg 71.1.2 EN12, under CLIA Q6D. Support is good but US and RINA have some reservations on the proposed amendments in green below for this EN ]:1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck. ] DISCUSS FURTHER AT SLF 54 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than 2

[710 mm ] [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all [this] [these] small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]]. [Coordinator’s Note post SLF 53:- For details of agreed changes and need for further consideration by CG in 2011 see comments at end of CLIA Q4, below.] R7.7 EN2 (Pipe area limit for limiting progressive flooding should be based on L?) Comments received from CLIA/CCSF between round 1 and 2: CLIA Q4 On cruise vessels, but also on other type of ships, there are a number of systems with small pipe diameters which may not have a significant influence on progressive flooding. The group is of the opinion that the ship size should be a criterion to determine the maximum allowable diameter or cross section area of pipes, for which progressive flooding can be ignored. The final wording has to be further discussed at the SDS WG.

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“The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than [710 mm2][an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all this small pipes should have a cross-sectional area of not more than [an equivalent pipe diameter of Ls/1000]]”. . Coordinator’s Comments: If the above is accepted, the wording of the last sentence could be tidied up slightly:[The total cross-sectional area of all [this] small pipes should [have a crosssectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]]”. CG Member’s Comments?:MI: Could agree to the co-ordinators revised text. Germany: Acceptable. Finland: Support. Italy: The co-ordinator’s proposal is supported. Norway: Do not support the suggestion at this stage. CLIA: Agree. US: Although we are willing to revisit this issue, the CLIA proposal requires justification and further discussion prior to accepting any changes. Historical note: The current 710 mm2 originated from the following IACS submission to the SDS CG between SLF 49 and 50: “By minor progressive flooding is assumed a [single] pipe penetrating a watertight subdivision and having an internal diameter of less than [0,03] m”. Round 2 Discussion: There is good support for CLIA’s proposal but US and Norway have some reservations. It is therefore proposed that we put the issue to the SLF 53 WG so that other members views can be expressed bearing in mind the historical background provided by the US. CLIA Q4 (for SLF53 WG). Do you support CLIA’s proposal (as amended if necessary)? Yes No Further Comments? Coordinator’s Note post SLF 53:- Some changes to the text of the EN were agreed to emphasize the WG’s feeling that it was the aggregate crosssectional area of all the small pipes (shown highlighted in grey, above). However we as coordinators remain of the opinion that “not exceed” reads better than “have a crosssectional area of not more that” (avoids repetition). We also made a note during the WG meeting that this entire issue should be reconsidered by the CG because of reservations by Norway and the US. CLIA Q4 (for Round 4 questionnaire). 1) Do you think that CLIA’s original proposal to change Reg. 7.7 EN2, as amended by the WG at SLF 53 (see below), is acceptable:2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than 2

[710 mm ] [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all [this] [these] small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]].

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2) If “yes” do you agree that the following wording for the second sentence, as proposed by the coordinators, is preferable?:The total cross-sectional area of all small pipes should not exceed an equivalent pipe diameter of Ls/1000] China, Finland, Italy, CLIA, MI, EC (however, it should be realised that this Q1 Yes makes the requirement (far) more stringent for smaller ships (< 150 m), while there is a relaxation for large ships which might be acceptable. Although there is no further justification why this would be necessary), Spain (It seems to be more correct to connect “minor progressive flooding” with the ‘size’ (length, tonnage) of the vessel, instead of assuming a fixed value. BUT, FOR PRACTICAL REASONS, a fixed value could be a good alternative for small vessels (i.e.: passenger vessels with Ls of less than 50 m, for these small vessels a cross-sectional limit area of 50/5000 and 50/1000 could be maintained allowing “minor progressive flooding”). Vanuatu, US, Sweden, Norway, Japan, RINA, Denmark, Germany No (Ls/1000 seems very much (e.g. equivalent pipe diameter for 300m vessel: 300m/1000=0.3m). No specific limit should be mentioned in this regulation. See proposal below as a possible compromise). Japan, China, Finland, Italy, CLIA, Spain, MI (agree that this text is Q2 Yes preferable) Vanuatu (can’t agree at this stage), Denmark No US (deleting the second “cross-sectional area” could cause some confusion). EC (Should this be Ls/5000? Ls/1000 gives a diameter of 25 cm, which seems not to be 'minor'.) Further Comments? (especially from US and Norway who have reservations on this entire issue):Vanuatu: We too have reservations; in part because we seem to be ignoring units and making no distinction between the uses of the piping in this discussion. Use of words like “total” and “equivalent” without referents is not conducive to clarity either. US: We agree that the current EN (that limits the total cross-sectional area of all pipes between any two watertight compartments to 710mm2 – an equivalent pipe diameter of 30mm) is quite strict, and therefore we are not opposed to some scale factor to account for ship size. We can generally accept the single pipe scale factor of Ls/5000, but we think the total cross-sectional area scale factor of Ls/1000 is excessive (it allows 25 max sized single pipes between any 2 compartments). We think Ls/2000 may be more appropriate, which would allow approximately 6 max sized single pipes between any 2 compartments. Sweden: Agrees with the US reservation. Norway: We are not against to limit the amount of progressive flooding in relation to the size of the vessel. However, we see that the former cross-sectional area of 710mm2 corresponds in the new guidelines for a vessel with Ls around 30 meters. The new guidelines is therefore a relaxation and needs to be considered more thoroughly with regard to bilge pumping capacity in relation to the “minor progressive flooding”. Furthermore, some wording should be included in the EN related to making sure that the safety of the ship is not impaired (bilge system not operation after damage, size of flooded compartment, A/R ratio etc.). Japan: In the case of small ships, Ls/5000 is too small, ex. Pipe diameter not more than 16 ϕ is required for the ships with Ls =80m, however generally used CO2 pipe diameter is more than 20

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ϕ

Japan thinks only the criterion of total cross–sectional area of all small pipes is needed. With regard to Q2, the criteria of total cross–sectional area of all small pipes, Japan supports coordinator’s proposal. [Co-ordinator’s Note: Sorry about the line spacing here!] China: We think the reason why Ls/1000 and Ls/5000 was determined, need to be clarified. RINA: The flow of water through the pipes, which are considered to lead to minor progressive flooding, should take into account issues such as: the total flow and whether this will be continuous; vertical distance from the damage waterline to the pipe outlet; how will the water in that space be controlled; whether the minor progressive flooding will have an impact on essential services in that space ,etc Denmark: Using Ls seems to unfairly penalise the piping and arrangement of smaller vessels, particularly since the pipe sizes of the systems in question are by and large fixed. It is also by no means established that Ls and pipe diameter are the only variables that correlate with the severity and survivability of progressive flooding. Germany: Proposal for compromise: [As guidance] the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with cross-sectional area of not more than an equivalent pipe diameter of Ls/5000 between any two watertight compartments. [The total area of such pipes should be a small as practicable, taking into account the position of the pipes, the size and location of the room.] France: It appears that there is a mistake in transcription of CLIA proposal. Equivalent diameter of Ls/1000 should be replaced by Ls/5000. Round 6 Discussion: For clarification, the question was asked whether the following text for reg. 7.7 EN2 as originally proposed by CLIA and modified by the SLF 53 WG was acceptable:2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a cross-sectional area of not more than an equivalent pipe diameter of Ls/5000 between any two watertight compartments. The total cross-sectional area of all these small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]. The co-ordinators had proposed that the text could be simplified further by using “not exceed” to avoid repeating the term “cross-sectional area” twice in the same sentence. The final square brackets were left in case of dispute over the size of the Ls/1000 term. These issues were returned to the CG for further discussion. In response to France’s comment we have checked the original CLIA proposal and confirm that it has been correctly transcribed. Regarding the units, use of “equivalent” and “total”, (Vanuatu’s points) we guess the EN means, for a ship of 50 metres in length Ls, for example, that no individual pipe should exceed 50/5000 metres (= 10mm) in diameter which is equivalent to 78.5 mm2 in cross-sectional area. The total diameter of all such individual pipes should not exceed 50/1000 metres (= 50mm) which is equivalent to a total cross-sectional area of 1963 mm2. This is clearly much greater than the figure of 710 mm2 which the original EN would have permitted (based on a single pipe of 30 mm diameter) and, as many have pointed out, represents a big relaxation for larger vessels (see graph below). For Ls =300 m, for example, the maximum total pipe diameter representing the upper limit for minor progressive flooding would be 300 mm (10 “standard” 30 mm pipes) or 70696 mm2 cross-sectional area.

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R7.7 EN2; Max Pipe Areas to avoid Minor Progressive flooding 5000.0

Pipe Area mm2

4000.0 Individual Pipe Area mm2 (CLIA) 3000.0

Total Pipe Area mm2 (CLIA) Total Pipe Area mm2 (Original)

2000.0 Total Pipe Area mm2 (US proposal) 1000.0

0.0 0

100

200

300

400

Ship Length Ls m

We have also shown the US proposal (Ls/2000) on the above graph for comparison. As Spain, EC, Japan and Denmark point out any simple ratio based only on Ls can produce difficulties, particularly for smaller vessels. For example, for Ls = 50 m the US proposal would lead to a maximum individual pipe diameter of only 10 mm, and a total pipe diameter of 25 mm. As Denmark says, there is no certainty that Ls and pipe diameter are the only variables to be considered (RINA provides details of other variables) and Norway points out that the bilge pumping capacity is of importance. Japan and Denmark mention standardized pipe diameters which are independent of ship length for engineering reasons (for example, the minimum diameter of a CO2 pipe is 20 mm, according to Japan). Proposal 1. To overcome some of these problems Germany proposes to keep Ls/5000 as the limit for individual pipes but not to set a limit for the total area of all pipes – saying that such area should be kept as small as practicable taking into account the position of the pipes, size of room etc. Proposal 2. As an alternative the co-ordinators propose keeping the current limit for total pipe area of 710 mm2 (one standard pipe of 30 mm diameter) for ships up to 150 m Ls. For ships of 150 m Ls and upwards we could adopt part of the US proposal by setting an upper limit of 6 standard pipes (180 mm diameter in total) for a vessel of length, say, Ls = 350 m and upwards and interpolating for intermediate Ls between 150 and 350 m, as shown below:-

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Total Pipe Area mm2 (co-ordinator's proposal) 30000

25000

Pipe Area (mm2)

20000

15000

10000

5000

0 0

50

100

150

200

250

300

350

400

Ship Length Ls (m .)

If a maximum figure for any individual pipe is still deemed necessary we suggest that this could be Ls/5000 m for ships of 150 m Ls and upwards (equating to approximately 1 standard pipe diameter at Ls = 150 m and 2 standard pipe diameters for Ls = 350 m). The wording of EN 2 would then become:2. For ships up to Ls = 150 m the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total 2

cross-sectional area of not more than 710 mm compartments.

between any two watertight

For ships of Ls = 350 m and upwards the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total 2

cross-sectional area of not more than 25500 mm compartments

between any two watertight

For ships between Ls = 150 and 350 m, the total cross-sectional area should be obtained by linear interpolation between the above figures. For ships of Ls = 150 m and upwards no individual pipe should exceed a diameter of Ls/5000 m.

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CLIA Q4D (for Round 6 questionnaire). Recognising that the use of ratios such as Ls/1000 and Ls/5000 can result in some anomalies, especially for smaller ships, would you agree to change EN 2 either along the lines proposed by Germany (Ls/5000 for individual pipes but no specific figure for the total area) or would you prefer to have all the figures specified as proposed above by the co-ordinators? Or is there a better way? Prefer Germany’s proposal? Prefer coordinator’s proposal?

Alternative proposal?

RINA (No), Germany (Yes), Poland (Yes) Japan, CLIA, UK, Denmark, Finland (with comment), Norway (with comment), China, Italy RINA (No), Germany (could be acceptable), US (Generally prefer the coordinator’s proposed approach; subject to further discussion and potential adjustment of the details), EC (Yes, seems reasonable. We believe that it is sufficient when the total cross sectional area is defined, so the last sentence of the proposal would not be necessary.) RINA: It is considered that the proposed EN amendments to limit the size of pipes are not necessary. See comments below. Germany: Delete numerical specification from the EN. France: (see below)

Further Comments? RINA: It is noted that the text regulation 7.7 as been amended by deleting the text which states that: “The Administration may permit minor progressive flooding, if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired.” No minor progressive flooding should be allowed unless it is controlled and it is documented in the damage stability control books/plan. If this text is added to the proposal then it follows that each minor progress flooding case should be assessed in the damage stability calculations and an assessment made on a case by case basis in accordance with the requirements stated above. Consequently it is not necessary to provide any controls on the size of the pipes. Finland: Co-ordinator’s proposal sets also limit for a total area of all pipes. Norway: We support in principal. However, the actual limit for vessels of Ls > 350 m should be evaluated, 25500 mm2 corresponds to 36 standard pipes. Germany: Any specification of “minor” by numbers is unfortunate. As e.g. Denmark and RINA point out, there are numerous factors affecting the amount of water and the relevance of the space flooded. A proposal would to delete the EN to just have the regulation 7.7 remain: “However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled …” This will allow for reasonable consideration of all possible arrangements according to each specific vessel. France: Calculations have been made to evaluate the maximum section of pipes through which progressive flooding may be neglected. Calculations have been made on three test ships, assuming following assumptions: - Such pipes induce progressive flooding for half of damage cases. - Amount of flooding water is calculated after 1 hour - Loss in attained index is limited to 0.002 ( which corresponds to the variation of attained index for a variation of about 2cm in GM of initial conditions for the test ships) Maximum volume of water resulting from progressive flooding through pipe has been calculated

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so that loss attained is limited to 0.002, assuming that progressive flooding occurs for half of damage cases. Progressive flooding is supposed to occur through for and aft watertight bulkhead of the compartment. Only critical damage cases for which survival factor is less than 1 are supposed to be affected. Three typical residual GZ curves are assumed. Section of pipes through each bulkhead which give such progressive flooding within 1 hour is then calculated. Results are the following :

Ship 1 Ship 2 Ship 3

Lpp m 289 205 44

Ls Displacement m t 323 76000 221 23000 46 800

Pipe area mm² 3260 1710 540

Calculated area should be considered as the total pipe area per bulkhead. From these results, proposed redaction of explanatory notes could be : For ships up to Ls = 150 m the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total crosssectional area of not more than 710 mm² between any two watertight compartments. For ships of Ls = 150 m and upwards total cross-sectional area of pipe should not exceed the equivalent of a diameter of Ls/5000 m. Comparison with proposed formula :

Ship 1 Ship 2 Ship 3

Ls m 323 221 46

Pipe area mm² 3260 1710 540

Proposed formula Ls/5000 with a minimum of 30mm Diameter Pipe area mm mm² 65 3278 44 1534 30 710

For small ships, it could be admitted to consider a shorter time. CLIA Q4

[Coordinator’s Note: There are two proposals for replacing reg. 7.7 EN2 – the majority favour option 2 but there are reservations – RINA, Germany, Norway and France. OPTION 1: 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total cross-sectional area of not more than [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total area of such pipes should be as small as practicable, taking into account the position of the pipes and the size and location of the room.]

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OPTION 2: [2. For ships up to Ls = 150 m the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total 2

cross-sectional area of not more than 710 mm compartments.

between any two watertight

For ships of Ls = 350 m and upwards the provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total 2

cross-sectional area of not more than 25500 mm compartments

between any two watertight

For ships between Ls = 150 and 350 m, the total cross-sectional area should be obtained by linear interpolation between the above figures. For ships of Ls = 150 m and upwards no individual pipe should exceed a diameter of Ls/5000 m]. ] DISCUSS AT SLF 54

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Regulation 7-1 Calculation of the factor pi General 1. The definitions below are intended to be used for the application of part B-1 only. 2.

In regulation 7-1, the words “compartment” and “group of compartments” should be understood to mean “zone” and “adjacent zones”.

3.

Zone – a longitudinal interval of the ship within the subdivision length.

4.

Room – a part of the ship, limited by bulkheads and decks, having a specific permeability.

5.

Space – a combination of rooms.

6.

Compartment – an onboard space within watertight boundaries.

7.

Damage – the three dimensional extent of the breach in the ship.

8.

For the calculation of p, v, r and b only the damage should be considered, for the calculation of the s-value the flooded space should be considered. The figures below illustrate the difference.

Damage shown as the bold square:

Flooded space shown below:

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Regulation 7-1 para 1 (ref. SLF 51/3/2 Annex – US and Sweden) In the definition of “b”, the term “deepest subdivision loadline” should be replaced by “deepest subdivision draught”. Regulation 7-1 para 1 (ref. SLF 52/17/5 Annex - Norway) Document SLF 51/3/2 contains a proposal that in the definition of “b”, the term “deepest subdivision load line” should be replaced by “deepest subdivision draught”. This seems to be an oversight made when the text was drafted and Norway proposes that the revision be implemented. R7-1.1 (Replace “load line” with “draught” (twice)) . Q28. Do you agree to the change proposed in SLF 51/3/2 and supported by Norway in SLF 52/17/5? Yes

China, Finland, Germany, Japan, MI, Norway, CLIA, Italy, Spain, Denmark, UK, US, Sweden

No Comments?:Spain: Probably it is better to use the term deepest subdivision draught instead of deepest subdivision load line. Additional question: is it needed any clarification or explanatory note in regulation 18 (Assigning, marking and recording of subdivision load lines for passenger ships)?

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Additional information: The term “deepest subdivision load line” is defined in regulation 2, it is the water-line which corresponds the greatest draught permitted by the subdivision requirements which are applicable. Deepest subdivision draught (ds) is the waterline which corresponds to the summer load line draught of the ship. ¿Differences? For example, the fresh water draught is higher than the summer load line draught, is it equivalent to the deepest subdivision load line or not? Round 1 Discussion: There is unanimous support for this - so it is proposed to adopt it. Spain has some questions - for example on EN for Reg. 18. We cannot see a definition for “deepest subdivision load line” in Reg. 2 as mentioned by Spain – could this comment be clarified, please? The load line is the physical mark denoting a particular assigned/calculated draught. In the context of the definition of “b” the draught in question is clearly ds. FW draughts etc are not really relevant here as they are all basically equivalent to ds but with allowances for different water densities, sea areas etc.

CONCLUDED - PROPOSAL ACCEPTED (SUBJECT TO CONFIRMATION BY SPAIN) Comments on Spain’s questions / any objections to accepting this proposal? CLIA: No objections. Round 2 Discussion: We are ready to accept Norway’s proposal subject to final clarification of comments and acceptance by Spain. Discuss in SLF 53 WG. Q28B (for SLF 53 WG). Can we all now agree to Norway’s proposal to replace “deepest subdivision load line” with “deepest subdivision draught” in the definition of “b”? Yes No Further comments (for example on Spain’s query regarding possible EN for reg. 18)?:Post SLF 53 comments:- It was agreed to replace “deepest subdivision load line” with “deepest subdivision draught”. Needs correcting as shown in SLF 53-WP.6:-

Q28C (for Round 4 questionnaire). Although it was agreed at the SLF 53 WG to replace “deepest subdivision load line” with “deepest subdivision draught” in the definition of “b” in Reg. 7-1.1, Spain still had one or two earlier related queries:“Additional question: is it needed any clarification or explanatory note in regulation 18 (Assigning, marking and recording of subdivision load lines for passenger ships)? Additional information: The term “deepest subdivision load line” is defined in regulation 2, it is the water-line which corresponds the greatest draught permitted by the subdivision requirements which are applicable. Deepest subdivision draught (ds) is the waterline which corresponds to the summer load line draught of the ship. ¿Differences? For example, the fresh water draught is higher than the summer load line draught, is it equivalent to the deepest subdivision load line or not?” Does Spain, or anybody else, wish to explore these questions further?

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Yes

No

UK – we support to propose change as the term “load line” is more in line with certification of the vessel to indicate operational limits which will result from the Index-A calculations of which this regulation constitutes a subset. France Vanuatu, US, Norway, China, RINA, Denmark , Germany, Finland, Italy, MI

Further comments?:France: Deepest subdivision draught is assumed in sea water condition. It may be necessary to specify that all calculations must be done with a sea water density of 1.025. Spain: The term “deepest subdivision load line” was included in Reg. 2 of previous SOLAS versions, it was our mistake!!! (sorry for the mistake...). Round 6 Discussion: Thank you Spain for clearing up the small misunderstanding. Regarding France’s comment on SW / FW, the use of SW seems to be assumed, for example, in reg. 18.5 and 18.7. For UK, the change from “subdivision loadline” to “subdivision draught” was unanimously agreed previously (except for Spain) so we propose to take no further action on this item.

Q28. CONCLUDED NO FURTHER ACTION AT THIS TIME. RECOMMEND “DEEPEST SUBDIVISION LOAD LINE” TO BE REPLACED WITH “DEEPEST SUBDIVISION DRAUGHT.” Any final comments / objections? US: Fully agree with this conclusion. China: No

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Regulation 7-1.1.1 [Coordinators Note: the following paragraphs 1-12, including the diagrams, are all EN] 1. The coefficients b11, b12, b21 and b22 are coefficients in the bi-linear probability density function on normalized damage length (J). The coefficient b12 is dependent on *

whether Ls is greater or less than L (i.e. 260 m); the other coefficients are valid irrespective of Ls Longitudinal subdivision 2. In order to prepare for the calculation of index A, the ship’s subdivision length Ls is divided into a fixed discrete number of damage zones. These damage zones will determine the damage stability investigation in the way of specific damages to be calculated. 3. There are no rules for the subdividing, except that the length Ls defines the extremes for the actual hull. Zone boundaries need not coincide with physical watertight boundaries. However, it is important to consider a strategy carefully to obtain a good result (that is a large attained index A). All zones and combination of adjacent zones may contribute to the index A. In general it is expected that the more zone boundaries the ship is divided into the higher will be the attained index, but this benefit must be balanced against extra computing time. The figure below shows different longitudinal zone divisions of the length Ls

4. The first example is a very rough division into three zones of approximately the same size with limits where longitudinal subdivision is established. The probability that the ship will survive a damage in one of the three zones is expected to be low (i.e. the sfactor is low or zero) and, therefore, the total attained index A will be correspondingly low. 5. In the second example the zones have been placed in accordance with the watertight arrangement, including minor subdivision (as in double bottom, etc.). In this case there is a much better chance of obtaining higher s-factors. 6.

Where transverse corrugated bulkheads are fitted, they may be treated as

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equivalent plane bulkheads, provided the corrugation depth is of the same order as the stiffening structure. [7. Pipes and valves directly adjacent to a transverse bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure. The same applies for small recesses, drain wells, etc.] [Coordinator’s Note:. There is a new proposal to harmonize the text with reg. 7.7 EN1 and reg. 7-1.1.2 EN 12, as highlighted in green, below. For full discussion see reg 71.1.2 EN12, below under CLIA Q6D. Support is good but Norway has some reservations on the proposed amendments in green below for this EN ]:7. Pipes and valves directly adjacent to a transverse bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc.] 8. For cases where the pipes and valves are outside the transverse bulkhead stiffening structure, when they present a risk of progressive flooding to other watertight compartments that will have influence on the overall attained index A, they should be handled either by introducing a new damage zone and accounting for the progressive flooding to associated compartments or by introducing a gap. 9. The triangle in the figure below illustrates the possible single and multiple zone damages in a ship with a watertight arrangement suitable for a seven-zone division. The triangles at the bottom line indicate single zone damages and the parallelograms indicate adjacent zones damages.

Z1

Z2

Z3

Z4

Z5

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Z6

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Figure illustrates the possible single and multiple zone damages in a ship. 10. As an example, the triangle illustrates a damage opening the rooms in zone 2 to the sea and the parallelogram illustrates a damage where rooms in the zones 4, 5 and 6 are flooded simultaneously.

11. The shaded area illustrates the effect of the maximum absolute damage length. The p-factor for a combination of three or more adjacent zones equals zero if the length of the combined adjacent damage zones minus the length of the foremost and the aft most damage zones in the combined damage zone is greater than the maximum damage length. Having this in mind when subdividing Ls could limit the number of zones defined to maximize the attained index A. 12. As the p-factor is related to the watertight arrangement by the longitudinal limits of damage zones and the transverse distance from the ship side to any longitudinal barrier in the zone, the following indices are introduced:

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END OF EN for Regulation 7-1.1.1

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Regulation 7-1.1.2 (ref. SLF 51/3/2 Annex – US and Sweden) Reduction factor “r” for damages of transverse extent limited to “b” is dependent on the length of the damage. This takes into account the fact that a breach of limited longitudinal extent cannot have a deep penetration. On the contrary, very long damages are raking type damages, so the probability to have a deep penetration may be reduced for very long damages. If minor damage above an intermediate deck is considered, depth of the breach below the waterline may be limited, so it can be obtained either from a raking damage or from a breach generated by a ramming ship with shallow draft. In both cases, the

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probability to have a deep penetration is low. This is not taken into account in the regulation. In all cases, the “r” factor should take account of the structural resistance of the ship to an external impact. --------------Regulation 7-1 para 1.2 (ref. SLF 52/17/5 Annex - Norway) Document SLF 51/3/2 contains a proposal that the “r” factor should take account of the structural resistance of the ship to an external impact. Although this Administration would agree that this principle could be made an option in the future, it is believed that extensive work is required to develop a unified method suitable for inclusion in the regulation. R7-1.1.2 (Should raking damage and structural resistance be taken into account?) Q29. In SLF 51/3/2 it is suggested:(a) that the regulations as they stand do not take into account the possibility that long raking damages will tend to have a shallower depth of penetration and (b) that the “r” factor should take into account structural resistance to side impact. In 52/17/5, Norway agrees with point (b) in principle but points out that it would require a great deal of work to bring into force. (a) Does “r” need modifying for raking damages? Yes or No:Yes: Germany (with comments), MI, US, Sweden No: China, Finland, Japan, Norway (not now), CLIA, Italy, Spain, Denmark, UK (b) Does “r” need modifying for structural resistance? Yes or No:Yes: Germany (with comments), Sweden No: China, Finland, Japan, Norway, CLIA, Italy, Spain, Denmark, UK, US, MI (may be too difficult, see comments) (a) Comments / suggestions / proposals / more consideration needed?:China: The probabilistic damage stability regulations of Part B-1 mainly deal with collision casualties; raking damages need not be considered. Therefore “r” need not be modified for raking damages. Finland: Before doing any changes to “r” more investigation is needed. It is preferable first to see effect of SOLAS2009 on design, before modifying “r”-factor. Germany: More investigations and data to support the approach needed. Norway: More extensive work is required; cf. SLF 52/17/5. “r” was never intended for raking damages as that was not within the TOR. Modification will be required if it is decided to include raking damages in the chapter. Spain:- S-2009 is a result of a lot of years of research. We know that the method involves many simplifications, but to change these assumptions of the method will involve a lot of new studies (new comparisons with the existing fleet, new statistic data, etcetera). From a practical point of view we prefer to maintain the basics assumptions and simplifications of S-2009. Denmark: We would prefer to see some research into the statistics, mechanics and implications before considering a change. Particularly since with probability, the frequency of raking damages compared to other damages is important US: The issue of raking damage should be further considered. France: [comment added in Round 2] Comment in SLF 51/3/2 was related to minor damages above intermediate decks which may not result from collision with a large ship. In this case, breach penetration probability should be linked to the position of the intermediate deck below the waterline.

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Round 1 Discussion: (a) Does “r” need modifying for raking damage? Four members agree that “r” should be modified for raking damage and nine disagree. However, of the 9 opposed to the idea 3 think that the issue needs some further research as do 2 of the 4 in favour. So the vote actually splits into 2 totally in favour, 5 require more research before deciding and 6 are totally opposed. So 11 out of 13 are not in favour of either immediate action or any action being taken at all. This suggests that the issue should be flagged up to SLF with a recommendation for it to be put on the “back burner” for now until more pressing issues are resolved. (b) Comments / suggestions / proposals / more consideration needed?:China: This is too complicated, absolutely “No”. Finland: Before doing any changes to “r” more investigation is needed. It is preferable first to see effect of SOLAS2009 on design, before modifying “r”-factor. Germany: More investigations and data to support the approach is needed. Japan: As Norway points out, this study requires a great deal of work. MI: The structural resistance to side impact will vary along the length of a ship depending on whether it occurs mid way between transverse bulkheads or near a bulkhead and is totally dependent on the size, trajectory and speed of the impacting ship. Suggest that this proposal may be too difficult to develop any further. Norway: There seems to be no imminent need to modify “r” for structural resistance, but we support that an option be developed at a later stage. Spain: Same comments as previous paragraph. Additionally, to evaluate the structural resistance of a certain area of a vessel (taking into account all the ship’s service life) is very complicated. Denmark: Structural resistance is indeed important and we would welcome research into how it could be accounted for. It seems though that having different r factors for different types of vessels is a move away from harmonisation (which may indeed be needed), is likely to increase complexity and may have undesired consequences and implications; we are thinking about vessels with changes in structure along the length of the vessel, vessels fitted with sponsons and of cruise vessels where a revision of the r factor may boost the A index. Round 1 Discussion: (b) Does “r” need modifying for structural resistance? Here the response is more clear-cut with 11 opposed and only 2 in favour, 1 of whom asks for more investigations and data. So in this case it also proposed that we flag up the issue with SLF for possible future consideration but with a somewhat lower priority than raking damage. Q29A Do you agree with the proposed actions for items (a) and (b)? (a) Report issue to SLF but recommend action be delayed Yes or No:Yes: MI, Germany, Finland, Italy, Japan, France (with comment), Norway, CLIA (with comment), UK, US, Sweden, Denmark No: China (b) Report issue to SLF but recommend action be delayed Yes or No:Yes: MI, Germany, Finland, Italy, Japan, Norway, CLIA (with comment), UK, US (with comment), Sweden, Denmark No: China (a) Comments / suggestions / further proposals? France: The issue of raking damage, or more generally probability of damage penetration according to damage length is an important issue that should be treated. But we can agree on the conclusion that this is a complicated item so it can be postponed waiting for further investigation, but such investigations should be encouraged by IMO. CLIA: But this issue requires a longer term approach as we are not in a position to move forward on it now due to a lack of statistical evidence. (b) Comments / suggestions / further proposals? France: This is also an important issue. Rules should encourage the design of ships having

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better resistance to impact of ramming ship, so we are not sure that this should have a lower priority than raking damage. CLIA: This is also a longer term objective. US: Regarding “action delayed”; for this item we believe the report should reflect the general view that although maybe technically correct, including structural resistance would be extremely complex and is therefore considered unfeasible at this time. Round 2 Discussion: It will be noted that the issues of raking damage and structural resistance to damage have been raised in the CG report (ref. SLF 53/14 paragraph 13.4) by asking the S-C whether we should continue to discuss them further in the CG prior to SLF 54 or whether they should be temporarily set aside pending further research.

AWAIT DECISION BY SUB-COMMITTEE AT SLF 53. (See SLF 53/14 para 13.4). Post SLF 53 Comment:- This issue was not discussed in plenary so we will assume no further action is needed for this CG session and bring it back for the S-C’s attention at SLF 54 unless any CG member has objections? Q29C (for Round 4 questionnaire). Are you happy that we should we leave these issues until at least SLF 54? Yes

Vanuatu, US, Sweden, Norway, Japan, China, RINA, Denmark, Finland, Germany, Italy, EC, CLIA, MI, France, ICS, Spain

No Comments?:Vanuatu: We submit that this matter is better dealt with by delegations writing papers proposing specific remedies on this matter; rather than comments in CG. Denmark: Pending further research. France: This subject would need further investigation and it is difficult to reach a conclusion before SLF 54. Round 6 Discussion: There is unanimous approval for this action. Perhaps these issues should be given a separate agenda item?

Q29. CONCLUDED WE WILL MENTION THE ISSUES OF RAKING DAMAGE AND STRUCTURAL RESISTANCE TO SIDE DAMAGE IN THE CG REPORT TO SLF 54.

RECOMMEND NFA UNLESS DIRECTED BY S/C (SLF 54/8/1 para. 15.4). Regulation 7-1.1.2 [Coordinator’s Note: the following paragraphs 1-12, including the diagrams, are all EN] Transverse subdivision in a damage zone 1. Damage to the hull in a specific damage zone may just penetrate the ship’s watertight hull or penetrate further towards the centreline. To describe the probability of penetrating only a wing compartment, a probability factor r is used, based mainly on the penetration depth b. The value of r is equal to 1, if the penetration depth is B/2 where B is the maximum breadth of the ship at the deepest subdivision draught ds, and r = 0 if b = 0. 2. The penetration depth b is measured at level deepest subdivision draught ds as a transverse distance from the ship side right-angled to the centreline to a longitudinal barrier.

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3. Where the actual watertight bulkhead is not a plane parallel to the shell, b should be determined by means of an assumed line, dividing the zone to the shell in a relationship b1/b2 with

4. Examples of such assumed division lines are illustrated in the figure below. Each sketch represents a single damage zone at a water line plane level ds and the longitudinal bulkhead represents the outermost bulkhead position below ds + 12.5 m.

Regulation 7-1.1.2 (ref. SLF 52/17/3 – Finland) There has been a general agreement, as stated in documents SLF 50/19 (paragraph 3.15) and SLF 51/3 (paragraph 5.8), on the need for further clarification of the transverse penetration depth. This is necessary because of complex waterline shapes. A proposal is made to add information to paragraph 1.2 in Reg II-1/7-1 in the Explanatory Notes as set out in the Annex. These two new paragraphs are preferably inserted between paragraphs 4 and 5 in the existing EN in Reg 7-1.1.2 “Transverse subdivision in a damage zone”. [See below]

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ANNEX TRANSVERSE SUBDIVISION INTERCEPTING THE HULL 4.1 If a transverse subdivision intercepts the deepest subdivision draught waterline within the extent of the zone, b is equal to zero (0) in that zone for the transverse subdivision in question, see figures 1 and 2.

In the above illustrated cases, b differing from zero (0) can be obtained by moving the aft limit of the zone according to figure 3 or by including an additional zone according to figure 4.

R7-1.1.2 New EN diagrams between EN 4 and EN 5 . Q30. Do you agree with the diagram additions to the EN for Reg. 7-1.1.2 between current EN 4 and 5 as first proposed by Finland in SLF 52/17/3? Yes China, Finland, Germany, Norway, Italy, Spain (but see comments), Denmark, UK, US, Sweden, MI (but see comments) No Comments / Alternatives?:Finland: Part of the waterline including multiple coordinates proposed in SLF 52/17/3 to be included also in EN. [Co-ordinator’s Note:- Many apologies, Finland – the missing part is now included below. We hope that those who said “yes” are also happy with the new part!]. MI: Think these cases are valid for inclusion but more detail of the orientation and value of ‘b’ needs to be added for consistency with the existing diagrams.

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Norway: Supports the intention of a unified interpretation. CLIA: see CSSF paper. Spain: Possibly, figure 3 is not necessary. We think that it could be acceptable to accept, taking into account figure 1, that b differing from zero. Regarding figures 3 and 4, the situation is more clear: the interpretation seems to be necessary. UK: It is the preferred option of the UK delegation that the use of “fictitious” zones must be allowed but kept to a minimum to avoid increasing the amount of calculations required. Round 1 Discussion: There is unanimous overall support for these proposed enhancements to the EN but there are one or two comments to be addressed before we can fully adopt them. MI would like more detail of the orientation, and the addition of “b”. Spain’s comments are a little unclear – they seem firstly to say that Fig. 3 is not necessary then in the next sentence that it is necessary. Can you please clarify this for us, Spain? The UK’s comment is appreciated - there is already something in the EN on the subject of “fictitious” zone boundaries being balanced against computing time but it is hard to see how this can be specified as it will vary from ship to ship and user to user (Ref. Reg 7-1.1.1 EN 3). Proposed Action: As some of the diagrams were omitted from the Round 1 questionnaire we will give more time for further consideration and invite Finland to see if it is possible to improve them still further along the lines suggested by MI. Also await clarification of Spain’s comments. Q30A: Please also examine the “missing” diagrams below; do you still agree with inclusion of all the diagrams in the EN and with MI’s request for more information to be shown? Yes MI, Germany, Finland, Italy, Japan, France (but see comments), Norway, CLIA, UK, US, Sweden, Denmark No China Comments / Regarding the EN figures in general – should we consider adding sequential figure numbers with titles throughout the EN for ease of reference? France: The proposed examples are not satisfactory from a theoretical point of view as actual probability not to damage longitudinal bulkhead in given example is not null, but they are in line with current explanatory notes. This is generally a pessimistic assumption, but may be not the case if symmetrical flooding is obtained with non limited damage extent. In addition, case where deepest waterline doesn’t intercept the aft terminal is not treated. France had made a proposal on this point which had not been retained in the final explanatory notes by lack of consensus, but they may be presented again. CLIA: Yes (add sequential numbering for figures in EN). US: Yes (add sequential numbering for figures in EN). Round 2 Discussion:- There is a good majority in favour of inserting these diagrams into the EN but France has some reservations; MI would like more explanation of the orientation and an indication of where “b” is. China is now opposed. There is support from CLIA and the US for adding sequential figure numbers throughout the EN for ease of reference. As there remain some issues unresolved with this item we proposed that it is discussed at the SLF WG. France may also wish to re-present the diagrams which were previously left out of the EN for further consideration. Q30B (for SLF 53 WG). In the lights of comments by France and the MI and China’s position, can we accept the diagrams as presented by Finland or do they need further clarification? Please also see further proposal by CLIA (below). Yes No Comments / would further clarification help, China?:Post SLF 53 comment:- It was agreed in the WG that Finland would clarify the figures to satisfy the Marshall Islands query and that France would re-present her diagrams which were previously left out of the EN.

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MISSING PART NOW ADDED:Part of the waterline including multiple coordinates 4.2 If the deepest external subdivision draught waterline on the studied side of a single hull ship includes a part where multiple transversal (y) coordinates occur for a longitudinal (x) location, a straightened reference waterline can be used for the calculation of b. If this approach is chosen, the original waterline is replaced by an envelope curve including straight parts perpendicular to the centreline where multiple transversal coordinates occur, see figures 1 to 4. The maximum transverse damage extent B/2 is then also calculated from the reference waterline.

Q30C (continued) (for Round 4 questionnaire). Can Finland and France please help us with revised and new diagrams as promised at SLF 53?

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Further thoughts or comments?:Denmark: No further thoughts. France: France will prepare an alternative proposal and will discuss it with Finland. Finland: Has supplied the following revised text and diagrams for the EN (see next two pages). Round 6 Discussion: Thank you, Finland. We hope this clarifies things for the MI and China? France may still have some issues, however. Here is a reminder of France’s comments on Finland’s previous diagrams, taken from the large working document:“The proposed examples are not satisfactory from a theoretical point of view as actual probability not to damage longitudinal bulkhead in given example is not null, but they are in line with current explanatory notes. This is generally a pessimistic assumption, but may be not the case if symmetrical flooding is obtained with non limited damage extent. In addition, case where deepest waterline doesn’t intercept the aft terminal is not treated. France had made a proposal on this point which had not been retained in the final explanatory notes by lack of consensus, but they may be presented again”. Are France and Finland in agreement? Q30D(for Round 6 questionnaire). Can we now accept these new diagrams and text for the EN? Japan, CLIA, Finland, Germany, Denmark, China, US (Subject to possible Yes? further refinements), Italy, UK (yes to 4.2 paragraph explaining “ Part of the waterline including multiple coordinates” ), No?

UK (no to 4.1 – see comments), France (see comments)

Further Comments? UK: It has already been discussed and the current treatment of the actual watertight bulkheads which is not a plane parallel to the shell. If one would like to be more accurate fictitious zones may be introduced. If the principle of limited b1(=2xb2) is observed then for the cases where measured b1=0 will be modified to 2xb2. France: §4.1 : Figure 1 : Waterline seems to intercept the longitudinal subdivision at a certain distance from the transverse subdivision, so b1 should not be 0 Figure 3 : If aft limit of the zone is the aft terminal, moving the aft limit will modify the subdivision length, which seems not acceptable, so in this case the only solution is to create an additional zone. §4.2 : In all figures, two transverse lines seems to limit the considered zone. In figure 1 and 3, the aft transverse line is very close to the aft end of the waterline, but, however, intercepts it - which suggests that the zone is not the aft zone. We propose to delete the aft line or to move it forward to have a more clear intersection with the waterline Q30 A MAJORITY OF 9-2 ARE IN FAVOUR OF THE NEW TEXT AND DIAGRAMS BELOW. HOWEVER FRANCE AND THE UK HAVE SOME SPECIFIC PROBLEMS AND THE US BELIEVES THAT FURTHER REFINEMENTS MAY BE NEEDED. DISCUSS AT SLF 54

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TRANSVERSE SUBDIVISION INTERCEPTING THE HULL 4.1 If a transverse subdivision intercepts the deepest subdivision draught waterline within the extent of the zone, b is equal to zero (0) in that zone for the transverse subdivision in question, see figures 1 and 2.

Figure 1

Figure 2

In the above illustrated cases b differing from zero (0) can be obtained by moving the aft limit of the zone according to figure 3 or by including an additional zone according to figure 4.

Figure 3

Figure 4

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Part of the waterline including multiple coordinates 4.2 If the deepest external subdivision draught waterline on the studied side of a single hull ship includes a part where multiple transversal (y) coordinates occur for a longitudinal (x) location, a straightened reference waterline can be used for the calculation of b. If this approach is chosen, the original waterline is replaced by an envelope curve including straight parts perpendicular to the centreline where multiple transversal coordinates occur, see figures 1 to 4. The maximum transverse damage extent B/2 is then also calculated from the reference waterline.

Figure 1

Figure 2

Figure 3

Figure 4

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R7-1.1.2 EN Extra comments received from CLIA/CCSF between round 1 and 2: A number of proposals have been made (also in relevant SLF52/17 papers) to deal with a clear interpretation for hull forms resulting in unusual waterlines. This proposal is supported by the group (comment from CLIA): .Additional Explanation: Where at the extreme ends of the ship the subdivision exceeds the waterline at the deepest subdivision draught, the damage penetration b or B/2 is to be taken from centre line. The following figure illustrates the shape of the B/2 line: deepest subdivision waterline

B/2 line

Coordinator’s Comments: CG Member’s Comments?:Germany: Acceptable. China: I cannot understand the above text. How to measure penetration “b” in this case? More detailed figure and/or explanation may be needed. Finland: Support. Italy: Agree with CLIA/CSSF explanation. France: See comments for Q30A. US: Not sure we understand the orientation of the B/2 line. (B/2 is a fixed value) EN2 for reg 7.5: In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. CLIA Q5. Round 2 Discussion:- There are mixed views on this proposal so it is suggested that it is discussed further at the SLF 53 WG in conjunction with Q30B, above. Post SLF 53 comments:- It was agreed in the WG to ask CLIA to improve their proposed diagram in the light of the above comments, particularly from China and the US, in time for SLF 54.

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CLIA Q5C (for Round 4 questionnaire) Can CLIA please help us with revising this diagram as promised at SLF 53? Space for Revised Diagram / Further thoughts or comments?:CLIA: May be best to come from Germany/France. Germany: (Has provided a new diagram – see below. Many thanks.) France: The sketch is acceptable to France. Co-ordinator’s Note: This refers to the above sketch, we suppose. Round 6 Discussion: We recall that China, US and France had issues with the old diagram. The following comments by the US are taken from the working document: “Not sure we understand the orientation of the B/2 line. (B/2 is a fixed value) EN2 for reg 7.5: In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth". CLIA Q5D (for Round 6 questionnaire). Can we now accept the revised diagram and proposed text for the EN (below)? Yes?

Japan, CLIA, Finland, Norway, Germany, Denmark, China, US (but see comments below), Italy, France, UK (yes, in principle, but see comments below)

No? Further Comments – especially US? Co-ordinator’s Note: The diagram is a little blurred. If accepted, could Germany please supply a clearer version? (See below – new diagram received in Round 6 responses). THANK YOU GERMANY.

12. Where at the extreme ends of the ship the subdivision exceeds the waterline at the deepest subdivision draught, the damage penetration b or B/2 is to be taken from centre line. The following figure illustrates the shape of the B/2 line:

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US: Will this diagram be included as an EN under Reg 7-1.1.2 or would it be better to incorporate it into the EN2 for reg 7.5? If incorporated into the EN2 for reg 7.5 (which we think fits better), the diagram text may need some minor edits to align with the existing text of EN2 for reg 7.5. UK: In order to enhance the diagram, we would like to suggest that the label “Penetration b” be replaced with “B/2”, and keep the rest the same. Perhaps another diagram can be used to show “penetration b” to a specific longitudinal bulkhead. CLIA Q5 THERE IS A VOTE OF 11-0 IN FAVOUR OF THIS TEXT AND DIAGRAM BUT THE US AND THE UK EACH HAVE SOME SUGGESTED IMPROVEMENTS. DISCUSS AT SLF 54

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10. A damage giving a transverse extent b and a vertical extent H2 leads to the flooding of both wing compartment and hold; for b and H1 only the wing compartment is flooded. The figure below illustrates a partial subdivision draught dp damage.

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11.

The same is valid if b-values are calculated for arrangements with sloped walls.

12. Pipes and valves directly adjacent to a longitudinal bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close practicable to the bulkhead [or deck], but exceeding in size the depth of the stiffening structure should still be assumed to be part of the bulkhead [or deck].

END OF EN for Regulation 7-1.1.2 [Coordinator’s Note: The changes to reg. 7-1.1.2 EN12 in grey below were agreed at SLF 53. There is a new proposal to harmonize the text with reg. 7.7 EN1 and reg. 71.1.1 EN 7, as highlighted in green, below. Note that the word “longitudinal” was in the original EN but had been removed. It is now proposed to restore it. [CLIA Q6D. Majority in favour but RINA Norway US and France have reservations; ]:[12][13]. Pipes and valves directly adjacent to a longitudinal bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc.

Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck.] R7-1.1.2 EN12 (Stiffeners may be small relative to pipes or valves) Comments received from CLIA/CCSF between round 1 and 2: CLIA Q6 (see also R7.7 EN1 and R7-1.1.1 EN7) Modification with regard to location of separation valves at watertight bulkheads and decks. Application in practice has shown that the size of the stiffeners might sometimes be too small for large pipe diameters. This is the same change as proposed for Reg. 7.7 EN2 above. The additional guidance for machinery is done to reflect physics as closely as possible. “Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be

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part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated within the distance defined above and as close practicable to the bulkhead, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead.” . Coordinator’s Comments: If this is acceptable we would suggest using “in size the depth” instead of “due to their size the order” in the last sentence:Valves which are situated within the distance defined above and as close as practicable to the bulkhead, but exceeding in size the depth of the stiffening structure should still be assumed to be part of the bulkhead.” CG Member’s Comments?:MI: Could agree to the co-ordinators revised text. Germany: Acceptable. Finland: Support. Italy: Agree with CLIA/CSSF. Japan: Supports coordinator’s suggestion. France: Depth of stiffening structure is not a practical limitation, so this proposal may be accepted. Maximum absolute value could be added (800mm or a percentage of B). Norway: It is perhaps a better option to handle such large diameter pipes and long spool pieces/valves as recesses, i.e. the zone limits are to be moved away from the bulkhead. CLIA: Agree. US: We can accept this proposed change. Text suggestion: delete the words within the distance defined above and because they are not (or we wouldn’t need this caveat). Note: (1) This text was copied from reg 7.7 EN1, which applies to both bulkheads and decks. This EN only applies to longitudinal bulkheads. (2) If this text is agreed to, it also shows up in reg 7-1.1.1 EN7 (for transverse bulkheads) and it would seem logical to make the same change there. Round 2 Discussion: We must point out that similar EN’s appear in two other places (reg. 7.7 EN 1 and reg. 7-1.1.2 EN 12). Also note that reg.7-1.1.1 EN 8 would support Norway’s position. For consistency we would either need to consider possible changes to all three EN’s or simply to leave all three as they are. CLIA Q6 (for SLF53 WG). Given that we have other EN’s covering the issues raised by CLIA do you think we should look at revising all three EN’s or should we leave them all alone? (See also CLIA Q3, above). Revise all 3 EN’s? Leave all 3 EN’s alone? Comments?:Post SLF 53:- It was agreed in the WG to amend the text as highlighted in grey, above but it may not be necessary to added the words “or deck” as the EN relates specifically to longitudinal bulkheads. CLIA Q6C (for Round 4 questionnaire). Should we remove the words “or deck” as shown in square brackets? Yes US, Sweden, Norway, Japan, China, Denmark, Spain, MI (agree removal of “or deck”) RINA (If the text is to be amended to include “deck” then the original text should also be amended).

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No

Vanuatu (retain for clarity), Germany, Finland, Italy, France.

Further thoughts or comments?:Vanuatu: We submit that it is conceivably possible that a pipe run through a bulkhead ells (L’s) into a deck, if this clarity is not provided, which way would the penny drop? China: “as close practicable” may be too vague. [Coordinator’s Note: We have also noticed that, if retained, this should read “as close AS practicable”.] RINA: The additional text in grey ” Pipes and valves directly adjacent to a longitudinal bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure…….” The proposed text “as far as practicable” does not impose any restriction which is intended by the original text. France: This paragraph refers to longitudinal bulkheads, but the same comment may apply to regulation 7.7 EN1 which refer to valves directly adjacent to bulkhead or deck. Round 6 Discussion: The co-ordinators seem to have become a little confused here the text shown for EN 12 is not that which was finally agreed to by the SLF 53 WG – we are sorry for this mistake. We need to look again more closely at all three places where EN’s beginning with “pipes and valves” occur - to try to ensure consistency. For ease of reference we will start in each case with the original regulation and EN then show how things were changed in the CG and by the SLF 53 WG:1) Reg. 7.7 7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. CLIA, between round 1 and 2 in last year’s CG, proposed to modify the original EN as highlighted below since “application in practice has shown that the size of the stiffeners might sometimes be too small for large pipe diameters”. 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated within the distance defined above and as close as practicable to the bulkhead, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead. CLIA Q3 After discussions in last year’s CG and in the WG at SLF 53 it was agreed to change the original EN as highlighted in grey (ref. SLF.53/WP.6 Annex 5, p. 39):1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The

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same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck. However, Norway expressed some reservations (WP.6, same reference):“Norway considers that it would be better to introduce new zone limits for large diameter pipes and valves/spool pieces”. The coordinators previously pointed out that similar EN’s appear in two other places (reg. 7-1.1.1 EN 7 and reg. 7-1.1.2 EN 12). Also note that reg. 7-1.1.1 EN 8 would support Norway’s position (at least when determining damage zone boundaries). For consistency we would either need to consider possible changes to all three EN’s or simply to leave all three as they are. 2) Reg. 7-1.1.1 The regulation is too lengthy to include here but relates to the calculation of factor p(x1, x2). There are 12 EN’s describing how the length Ls is subdivided into damage zones. EN7 and EN8, under the general heading of “longitudinal subdivision”, state the following:7. Pipes and valves directly adjacent to a transverse bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure. The same applies for small recesses, drain wells, etc. 8. For cases where the pipes and valves are outside the transverse bulkhead stiffening structure, when they present a risk of progressive flooding to other watertight compartments that will have influence on the overall attained index A, they should be handled either by introducing a new damage zone and accounting for the progressive flooding to associated compartments or by introducing a gap. There have been no questions or discussions on EN’s 7 or 8 by the CG. 3) Reg. 7-1.1.2 This regulation (also lengthy) covers the calculation of factor r(x1, x2, b) relating to the side penetration depth. There are 12 EN’s under the general heading “Transverse subdivision in a damage zone”. The original EN 12 reads as follows:12. Pipes and valves directly adjacent to a longitudinal bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure. The same applies for small recesses, drain wells, etc. The text is very similar to Reg. 7.7 EN 1 except that “longitudinal bulkhead” replaces “bulkhead or to a deck” and the words “bulkhead or deck” are replaced each time with “bulkhead” (clearly referring to the longitudinal bulkhead). Reg. 7-1.1.1 EN 7 is exactly the same as the above except that “transverse” replaces “longitudinal”. CLIA, between round 1 and 2 in last year’s CG, proposed to make the following changes as highlighted making the EN exactly the same as their proposal for Reg. 7.7 EN 1:12. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the

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bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated within the distance defined above and as close as practicable to the bulkhead, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead. After discussion in last year’s CG and in the WG at SLF 53 it was agreed to change the original EN as highlighted in grey (ref. SLF.53/WP.6 Annex 5, p. 57):12. Pipes and valves directly adjacent to a longitudinal bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck. It should be noted that, in the new sentence which begins “Valves which …. etc” the SLF 53 WG made some changes to this EN which were not made in EN 1 for Reg. 7.7. For example “due to their” was replaced with “in” and “order” with “depth”. As co-ordinators, we prefer this version so propose that EN 1 for Reg. 7.7 be changed accordingly. SUMMARY – LATEST AGREED TEXTS To try to improve consistency in the EN for the three regulations we have placed the latest agreed versions together below to make it easier to see the differences. The currently agreed changes are highlighted in grey:Reg 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck. Reg. 7-1.1.1 7. Pipes and valves directly adjacent to a transverse bulkhead can be considered to be part of the bulkhead, provided the separation distance is of the same order as the bulkhead stiffening structure. The same applies for small recesses, drain wells, etc. 8. For cases where the pipes and valves are outside the transverse bulkhead stiffening structure, when they present a risk of progressive flooding to other watertight compartments that will have influence on the overall attained index A, they should be handled either by introducing a new damage zone and accounting for the progressive flooding to associated compartments or by introducing a gap. Reg. 7-1.1.2 12.

Pipes and valves directly adjacent to a longitudinal bulkhead or to a deck can be

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considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck. PROPOSED CHANGES FROM CURRENTLY AGREED TEXT TO IMPROVE CONSISTENCY – HIGHLIGHTED IN GREEN BELOW Reg 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck. Reg. 7-1.1.1 7. Pipes and valves directly adjacent to a transverse bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. 8. For cases where the pipes and valves are outside the transverse bulkhead stiffening structure, when they present a risk of progressive flooding to other watertight compartments that will have influence on the overall attained index A, they should be handled either by introducing a new damage zone and accounting for the progressive flooding to associated compartments or by introducing a gap. Reg. 7-1.1.2 12. Pipes and valves directly adjacent to a longitudinal bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck. CLIA Q6D (for Round 6 questionnaire). To improve consistency, could you accept the proposed texts for the three EN’s as highlighted above in green? Yes?

Japan, CLIA, RINA (see comments below), Finland, Denmark, Norway (with comment), Germany, US (Partially, see comments), Italy, UK, EC, China, France (with comment)

No?

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Further thoughts or comments?:RINA: See RINA comments to CLIA-Q4D repeated below for ease of reference : It is noted that the text regulation 7.7 as been amended by deleting the text which states that: “The Administration may permit minor progressive flooding, if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired.” No minor progressive flooding should be allowed unless it is controlled and it is documented in the damage stability control books/plan. If this text is added to the proposal then it follows that each minor progress flooding case should be assessed in the damage stability calculations and an assessment made on a case by case basis in accordance with the requirements stated above. Consequently it is not necessary to provide any controls on the size of the pipes. Norway: We agree to the editorial changes for consistency. However, we are still of the opinion that it is better to introduce new zone limits for large diameter pipes and valves/spool pieces. US: Our preference is that only the EN for reg 7.7 include “deck” (i.e. that reg 7-1.1.1 only be for “transverse bulkhead” and reg 7-1.1.2 only be for “longitudinal bulkhead”). This is because reg 7-1 does not address horizontal subdivision issues, which are only handled by the v-factor in reg 7-2.6. Therefore it seems sufficient to cover decks under the general provision in reg 7.7. Also this does not address the consistency issue regarding reg 7-1.1.1 EN 7 and EN8 where you don’t get the new “valves which are situated as close as practicable...” option. For these valves they must “be handled either by introducing a new damage zone and accounting for the progressive flooding to associated compartments or by introducing a gap”. So this actually conflicts with the general provision in reg 7.7 that seems to apply broadly. This is generally related to the issue Norway expressed concern about. Although we have no strong view on which way to go, we think this needs further discussion in the WG. France: Paragraph 7-1.1.2, refers to transverse subdivision, so only longitudinal bulkhead are concerned. The tolerance is only useful for valves situated outside of the bulkhead referring to centreline, but as stiffening structure may be on either side, proposed wording is correct. CLIA Q6 [Coordinator’s Note: The changes to reg. 7-1.1.2 EN12 in grey below were agreed at SLF 53. There is a new proposal to harmonize the text with reg. 7.7 EN1 and reg. 71.1.1 EN 7, as highlighted in green, below. Note that the word “longitudinal” was in the original EN but had been removed. It is now proposed to restore it]. [ All in favour but RINA Norway US and France have reservations; ]:[12][13]. Pipes and valves directly adjacent to a longitudinal bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance on either side of the bulkhead or deck is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc.

Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their in size the order depth of the stiffening structure should still be assumed to be part of the bulkhead or deck.] DISCUSS FURTHER AT SLF 54

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Regulation 7-2 Calculation of the factor si General 1. Initial condition – an intact loading condition to be considered in the damage analysis described by the mean draught, vertical centre of gravity and the trim. Or alternative parameters from which the same may be determined (eg. displacement, GM and trim). There are three initial conditions corresponding to the three draughts ds, dp and dl. 2. Immersion limits – immersion limits are an array of points that are not to be immersed at various stages of flooding as indicated in regulations 7-2.5.2 and 7-2.5.3. 3. Openings – all openings need to be defined: both weathertight and unprotected. Openings are the most critical factor to preventing an inaccurate index A. If the final waterline immerses the lower edge of any opening through which progressive flooding takes place, the factor “s” may be recalculated taking such flooding into account. However, in this case the s value should also be calculated without taking into account progressive flooding and corresponding opening. The smallest s value should be retained for the contribution to the attained index. 1 The factor si shall be determined for each case of assumed flooding, involving a compartment or group of compartments, in accordance with the following notations and the provisions in this regulation.

θe is the equilibrium heel angle in any stage of flooding, in degrees; θv is the angle, in any stage of flooding, where the righting lever becomes

negative, or the angle at which an opening incapable of being closed weathertight becomes submerged; GZmax is the maximum positive righting lever, in metres, up to the angle θv;

Range is the range of positive righting levers, in degrees, measured from the angle θe. The positive range is to be taken up to the angle θv; Flooding stage is any discrete step during the flooding process, including the stage before equalization (if any) until final equilibrium has been reached.

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Regulation 7-2.1 1. In cases where the GZ curve may include more than one “range” of positive righting levers for a specific stage of flooding, only one continuous positive “range” of the GZ curve may be used within the allowable range/heel limits for calculation purposes. Different stages of flooding may not be combined in a single GZ curve.

2. In figure 1, the s-factor may be calculated from the heel angle, range and corresponding GZmax of the first or second “range” of positive righting levers. In figure 2, only one s-factor can be calculated. 1.1 The factor si, for any damage case at any initial loading condition, di, shall be obtained from the formula: si = minimum { sintermediate,i or sfinal,i x smom,i } where: sintermediate,i is the probability to survive all intermediate flooding stages until the final equilibrium stage, and is calculated in accordance with paragraph 2; sfinal,i is the probability to survive in the final equilibrium stage of flooding. It is calculated in accordance with paragraph 3; smom,i is the probability to survive heeling moments, and is calculated in accordance with paragraph 4.

2 The factor sintermediate,i is applicable only to passenger ships (for cargo ships sintermediate,i should be taken as unity) and shall be taken as the least of the s-factors obtained from all flooding stages including the stage before equalization, if any, and is to

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be calculated as follows:

where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. sintermediate,i = 0, if the intermediate heel angle exceeds 15º. Where cross-flooding fittings are required, the time for equalization shall not exceed 10 min. Regulation 7-2.2 (ref. SLF 51/3/2 Annex – US and Sweden) “sintermediate” should vary progressively as a function of heel. Therefore the proposal would be to have a K factor as for “s final”:

where: Kint = For final equilibrium θmax is of 15 degrees compared to 12 deg in present SOLAS. For intermediate stages, maximum angle of 15 deg would give a θmax of 18.75 deg. Proposed values may be: θmin-int = 10 degrees θmax-int = 18 degrees R7-2.2 (changes to sintermediate, i ) . Q31. Do you agree with the above modifications to Reg 7-2.2? Yes

MI, Norway, Denmark, Sweden

No

Finland, Germany, Japan, UK, US, Italy

Comments / Alternatives / More consideration needed?:China: The influence of new factor “Kint” should be investigated. Finland: This modification would need more investigations. NO preferred. Japan: Further consideration should be needed. Norway: Supports to include a formula, however the actual values needs further consideration. CLIA: Don’t know the impact. Italy: Not agreed, this methodology was never assumed when analysing the initial sample ships.

Spain: We need more information about this proposal. Anyway, we think that the following sentence should be added to this proposal: “where: Kint = 1 if θe ≤ θmin Kint = 0 if θe ≥ θmax”

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As far as we understand, compared with present S-2009, the situation is as follows: Present S-2009 US and Sweden proposal (same sint values) kint = 1 (same sint values) θe-int ≤ 10 º (higher s values) (lower sint values) 10 < θe-int ≤ 15 º int sint ≥ 0 sint = 0 15 < θe-int < 18 º sint = 0 sint = 0 θe-int ≥ 18 º Representing the situation in a graphical way:

sint (currentS-2009) / sint (newproposal) 2,00 1,80 1,60 1,40 1,20 1,00 0,80 0,60 0,40 0,20

Equilibrium angle (º) 0,00 0

2

4

6

8

10

12

14

16

18

20

We have two main concerns about the proposal: -

To permit a maximum equilibrium angle for intermediate stages of 18º is possibly too much for a passenger vessel (panic, difficulties in evacuation, etcetera). This equilibrium angle could be maintained during 10 minutes. - We do not know the practical effect of reducing the values of sint between 10º and 15º. We suggest analyzing the effect in a passenger vessel database, before the final decision. END of SPAIN’s COMMENTS US: More consideration of this issue is appropriate. However, generally we don’t think this type of “scale” factor is necessary for an intermediate stage “s”. Round 1 Discussion: Opinion is fairly evenly divided on this issue – 4 in favour and 6 against. However, of those in favour only Norway has comments positively supporting a new formula (not necessarily this one) but, in common with 5 other members, thinks that more consideration of this proposal is needed before adoption. Italy is against it altogether, arguing that adopting this methodology would invalidate the sample ship calculations [which led to the determination of “R”, implying that previous work would need to be repeated using the new Kint factor]. Spain contributes a graph showing the effect on sint of introducing the heel scaling factor Kint and is concerned about the use of 18 degrees as a maximum heel angle criterion over a possible interval of 10 minutes on a passenger ship. Spain wants further consideration as does the US but the latter doubts if a scale factor such as Kint is necessary for sint; CLIA would like to know the likely impact. . Although the proposal is taken from a joint US/Sweden paper SLF 51/3/2 it may not necessarily

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have come from these countries. It seems that more justification of the need to modify sint, (from the proposal’s originator, if possible) may help to convince us that the extra work involved is strictly necessary. Q31A In light of the views expressed, particularly the request for further consideration, do you agree that we should ask for more background from the originator of the proposal on the need for introducing factor Kint, especially as it may involve considerable extra research work, as highlighted by Italy? Yes MI, Germany (with comment), Finland, Italy (with comment), Japan, Norway, CLIA, US, Sweden, Denmark No UK (with comment) Comments / Alternative suggestions? Germany: We would assume a considerable impact of such change, therefore a detailed analysis is needed before any decision is taken. Italy: More background is always welcome, however we do not support new methodologies on this specific issue. France: When establishing SOLAS2009, maximum heel values have been determined in comparison with SOLAS90. K factor in sfinal formula gives a value of 1 if heel is less than or equal to 7° which was the minimum value of maximum heel for SOLAS90. However, contribution to attained index is still taken into account up to a heel angle of 15° which exceed the maximum heel of 12° admitted for SOLAS90. If similar approach is adopted for sint, maximum heel of 15° should be applied to obtained an s=1, but contribution may still be considered for larger heel angles. As explained, the proposed value is obtained so to have an extrapolation from 15° comparable to this from 12 to 15° adopted for heel in final stage. Range from 10° to 18° is proposed to have values comparable to the range 7° to 15° for final equilibrium, but other values may be adopted. ( Range from 12° to 18° would keep a mean value of 15°. Present formulation for sint is not in line with probabilistic concept ( s=1 if heel = 15.000° and s=0 if heel = 15.001°). UK: No, not because argument is not substantial enough, mainly we think that rather than plugging in an another artificial factor which may affect the overall calibration of the attained index i.e. required index, this must be considered in a wider context of factor-s formulation. Therefore it should not be adopted here. US: Clarification note: The joint Sweden/US paper SLF 51/3/2 was a SDS CG report; it was not a Sweden/US position paper. Specifically, SLF 51/3/2 submitted the composite “holding file” of assorted items to potentially address at some point in the future. From my archival records this particular proposal regarding Kint was made by France. Round 2 Discussion:- Thank you France for explaining the reasoning behind this proposed change. What do the CG members think? Q31B (for SLF 53 WG) In light of the explanation for the changes to the formula for sintermediate, i now provided by France can you agree to their proposal? Yes No Comments / Alternative suggestions? Post SLF 53 Comment:- There was little support for this proposal by France in the WG and it was therefore not adopted. Q31C (for Round 4 questionnaire) Any final comments?:Comments?:China: No comments. RINA: No comment at this time.

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Denmark: No further comments. Germany: No further comments. Italy: Still NOT ACCEPTED. EC: Ongoing research might have a bearing on this. Results of this research should be taken into account. France: France is still convinced that this would improve the method without increasing significantly the complexity of calculations. It is experienced that with present formulation, significant steps in attained index may be observed for a very low variation in GM. This can raise doubts in calculation procedure when analysing the results. To be more in line with the actual limit of 15 deg, we would amend our proposal by fixing : θmin-int = 12 deg θmax-int = 18 deg Spain: To permit a maximum equilibrium angle for intermediate stages of 18º is possibly too much for a passenger vessel (panic, difficulties in evacuation, etcetera). This equilibrium angle could be maintained during 10 minutes (it is not only for a seconds). We think that 15º is an acceptable value for a maximum intermediate equilibrium angle. Round 6 Discussion: As France has made a further proposal we feel obliged to reopen this matter for further comments and, if necessary, to discuss it again at SLF 54, remembering that we are now no longer bound by the restriction to maintain the same safety level as previous SOLAS. If the completion date for this agenda item is extended for another year, it may, as EC suggests, be better to wait for the outcome of ongoing research projects, particularly GOALDS, where the “s” factor is being re-examined and we understand that a problem similar to the one noted by France (rapid change in A arising from small change in GM) has emerged. There is also a point made by Spain (see Q32D, below) that if we decide to apply intermediate stage flooding to cargo ships, as proposed by Norway and supported by several other members, then we would need to re-examine the formula for sintermediate anyway, which is specific to passenger ships (e.g. sint=0 for heel > 15 deg whereas the maximum heel for cargo ships is 30 degrees). For easy reference, France’s original proposal is shown below:Regulation 7-2.2 “sintermediate” should vary progressively as a function of heel. Therefore the proposal would be to have a K factor as for “s final”:

where: Kint = For final equilibrium θmax is of 15 degrees compared to 12 deg in present SOLAS. For intermediate stages, maximum angle of 15 deg would give a θmax of 18.75 deg. Proposed values may be: θmin-int = 10 degrees θmax-int = 18 degrees Note that France is now proposing to change θmin-int from 10 to 12 degrees. Q31D (for Round 6 questionnaire). Do you agree that we should delay completing this item until further research into possible changes to the “s”- factor is available?

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Yes? No?

Japan, CLIA, RINA, Finland, Norway, Germany, Poland, Italy, UK, China, Denmark, France (see comment below), EC (Yes, the on-going research may have a bearing on this.) US (We think we should try to close some items)

Have you any further thoughts or comments?:France: Note that within GOALDS project a new formulation for survival factor is proposed, but it applies only to final stage of flooding and there is no real new criterion proposed for intermediate stages of flooding. Q31. R7-2.2 THIRTEEN MEMBERS PREFERRED TO AWAIT NEW RESEARCH INTO “s-factor”. US OPPOSES, BELIEVING WE SHOULD CLOSE THIS ITEM. DISCUSS AT SLF 54 ----------------------------------Regulation 7-2.2 (ref. SLF 52/17/6 - Norway) Document SLF 51/3/2 mentions that “several delegations believed that intermediate stages of flooding should be considered for some cargo ships and that this issue should be revisited in any future revision of the regulations.” This Administration agrees with this view, but this issue needs further consideration before such criteria can be developed. As an interim measure it is proposed that the first sentence be amended to cover passenger ships only: “2 For passenger ships the factor sintermediate,i is [applicable only to passenger ships (for cargo ships sintermediate,i should be taken as unity) and shall be] taken as the least of the s-factors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:” ……. The following text reflecting what is already included with respect to cargo ships in the EN is then added at the very end of the paragraph: “For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is found [anticipated] that the ship would capsize and sink during the intermediate stages, in which case sintermediate,i is taken as 0.” [Coordinator’s Note: The complete text of Reg 7-2.2, proposed as an interim measure by Norway in SLF 52/17/6, would then become]:“2 For passenger ships the factor sintermediate,i is taken as the least of the sfactors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:

For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is found [anticipated] that the ship would capsize and sink during the intermediate stages, in which case sintermediate,I is taken as 0.”

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R7-2.2 (apply intermediate stage flooding to cargo ships) . Q32. Do you agree with the above interim re-drafting of Reg 7-2.2 as proposed by Norway? (But see also Q34 regarding the EN, below, before answering). Yes

Finland, Germany, Norway, Italy, Spain, Denmark, UK, US, Sweden

No

China, Japan, MI

Comments / Alternatives?:China: China reserves the position that for cargo ships the stability in intermediate stages of flooding need not be considered. CLIA: Norway version. Don’t know effects. Spain: The term “would capsize and sink during the intermediate stages” should be clarified. Denmark: Including the Kint factor in the formula (Q31). We support the view that intermediate stages of flooding should be considered for cargo vessels particularly for cross-flooding. However we would like to know the reasoning behind the original exclusion of intermediate stages for cargo vessels. US: Although we are generally supportive of this approach, this issue requires further consideration. Round 1 Discussion: Nine out of 13 support this proposal; with 3 opposed and CLIA doubtful of the effects (however, as it would only affect cargo ships, it may not concern them). Of those against, only China has a comment; of those in favour Spain requires some clarification, Denmark would like to know why cargo ships were originally omitted and the US would prefer some further consideration. Norway realises that the issue needs further consideration and their proposed change to the regulation is therefore only an interim measure. Another point is that Norway is proposing to introduce new regulatory text which is rather more explicit than that already agreed to in the current EN, and will give it mandatory status. EN 9 currently reads:Cargo ships 9. If the Administration considers that the stability in intermediate stages of flooding in a cargo ship may be insufficient, it may require further investigation thereof. Although a significant majority support Norway’s proposal, we should also bear in mind the responses to Q34 where a majority of 8 to 5 preferred to keep EN 9 as it is rather than change it into a regulation. We should also note that there is a considerable difference between “found” and “[anticipated]” in Norway’s proposal; the former implies a full calculation with extra work for the designer whereas the latter implies a judgement based on previous experience and possible discussions with the Administration. Italy’s comments in answer to Q30 should surely also be taken into account as well, since applying intermediate stage flooding, as proposed by Norway, to the original sample of cargo ships could imply that “R” would need to be revised. A further point is that the “complete” text of Reg 7-2.2 given in the co-ordinator’s note in Round 1 omits the limits for GZmax and range as well as the sentence relating to cross-flooding. The full regulation as proposed by Norway should therefore read something like:-

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“2 For passenger ships the factor sintermediate,i is taken as the least of the sfactors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:

where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. sintermediate,i = 0, if the intermediate heel angle exceeds 15º. For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is found [anticipated] that the ship would capsize and sink during the intermediate stages, in which case sintermediate,I is taken as 0. [For passenger and cargo ships], where cross-flooding fittings are required, the time for equalization shall not exceed 10 min.” Presumably, if Norway’s proposal were to be adopted, EN 9 could be deleted? Finally, if we use “found” rather than “anticipated” in adopting Norway’s interim proposal, the implication is that a full stage-flooding calculation would also be needed for cargo ships. If we then equate “capsize and sink” with either GZmax or range = 0 or intermediate heel exceeding 15 degrees, then we may as well simply require passenger and cargo ships to be fully checked for sintermediate, i, changing the opening wording of the existing regulation to:2 The factor sintermediate,i is applicable only to passenger [and cargo] ships (for cargo ships sintermediate,i should be taken as unity) and shall be taken as the least of the s-factors obtained from all flooding stages including etc ……… and deleting EN9. Summary. Given that 3 members are either opposed to any changes to Reg 7-2.2 and EN 9 for cargo ships or would like any reference to intermediate stage flooding for cargo ships removed altogether, it seems there are now 4 options open to us: Option 1: Apply intermediate stage flooding only to passenger ships. Remove (for cargo ships ……. as unity) in Reg 7-2.2 and delete EN9. Option 2: Leave Reg 7-2.2 and EN 9 as it stands – the Administration decides if further investigation is needed. Option 3: Accept Norway’s proposal with the wording of the Regulation 7-2.2 as outlined above using the “anticipated” option in square brackets (slight word changes such as improving “capsize and sink” may also be needed) and delete EN9. Option 4: Apply intermediate stage flooding to both cargo and passenger ships. Modify the opening sentence of Reg 7-2.2 as shown above and delete EN9. . Q32A. Bearing in mind also your previous response to Q34, please indicate which of the above 4 options you prefer – or give alternatives. Option 1 China

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Option 2

MI, France (with comments), Sweden

Option 3

Germany, Italy, Japan (with comment), Norway (with comment), UK, Denmark

Option 4

US

Comments / Alternatives?:Japan: Japan prefers “anticipated”. France: This question has been discussed several times and a compromise has been found as written in explanatory notes. Formulation « in those cases where it is found [anticipated]” suppose that calculations have been done. (Is it possible to anticipate such problems without doing calculations?). If such calculations are done, it would be logical to take them into account even if they don’t influence the attained index. Norway: To Denmark’s query on exclusion of intermediate stages for cargo ships: The HARDER project proposed including intermediate stages for cargo ships but this was turned down by a small majority of members of the SDS correspondence group to SLF 47 with the argument that it was not required under the old chapter (i.e. not within the terms of reference). See SLF 47/3/2 paragraph 13. CLIA: Not directly relevant - cargo ship issue. Round 2 Discussion:- Many thanks to Norway for providing the historical background to Denmark’s query in round 1. Opinion favours option 3 but it is by no means unanimous so the matter will have to go to the SLF 53 WG for further discussion to see if agreement can be reached. Option 2 (3 supporters) favours keeping the regulation and EN as they are. Option 3 (6 supporters) favours changing the text as follows and deleting EN 9. 2 For passenger ships the factor sintermediate,i is taken as the least of the sfactors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:

where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. sintermediate,i = 0, if the intermediate heel angle exceeds 15º. For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is [found] [anticipated] that the ship would capsize and sink during the intermediate stages, in which case sintermediate,I is taken as 0. [For passenger and cargo ships], where cross-flooding fittings are required, the time for equalization shall not exceed 10 min.” France questions whether it is possible to anticipate whether a ship will capsize and sink during intermediate stage flooding without undertaking full stage-flooding calculations. Q32B (for SLF 53 WG). Can you accept the majority view in favour of Norway’s interim proposal shown in the round 2 discussion above? If so, would you prefer use of the word “found” or “anticipated” as shown in square brackets? Do you Denmark, Finland, Italy : yes (comments added in Round 4 response) accept Norway’s proposal?

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If yes, do you Denmark, Italy : prefer “anticipated” Finland : “found”. Refer also comment from France in Q32A prefer “found” or (comments added in Round 4 response) “anticipated”? Further Comments / Alternatives?:Post SLF 53 Comment:- This item was discussed in some depth and, as reported in the report of the WG to plenary, option 2 from the Round 1 discussion notes was preferred (i.e. leave the regulation and EN unchanged, thereby allowing the Administration to decide if further investigation is needed for cargo ships). However, the WG chairman said that because of the variety of views expressed this issue could be re-opened in the 2011 CG. Q32C (for Round 4 questionnaire):- This question relates to Norway’s interim proposal to calculate intermediate stages of flooding for cargo ships. For the full background and earlier discussions see the working document. As stated, the WG at SLF 53 preferred to make no changes but the chairman left the issue open for discussion in the 2011 CG. Do you therefore support Norway on this issue or do you prefer to leave the regulation as it stands? Q34 covers the EN. Support Yes: US, Norway, Finland Norway? No: Vanuatu Other: Spain (In general terms yes, but we think that the sentence “would capsize and sink” should be clarified (based on s value calculations?, using passenger vessel criteria?). Obviously, it is not possible in cargo vessels to assume the same formula to evaluate the stability during intermediate stages of flooding, because, for example, in a cargo vessel a maximum final equilibrium angle of 30º is permitted (in the formula, only 15º is permitted for intermediate stages of flooding). As a conclusion: 1) The best solution is to generate a new specific formula or criteria for cargo vessels intermediate stages of flooding. 2) If this solution is not possible, maybe a compromise solution is to add a sentence similar to the included in MARPOL Annex I: “The Administration shall be satisfied that the stability is sufficient during intermediate stages of flooding”.) No change? Japan, China, Denmark, Germany, Italy, MI (leave as is) Further Comments?:Vanuatu: We align ourselves with Spain’s comment as reported from WG. Capsizing and sinking are two separate conditions; the second doesn’t necessarily follow the first, and not immediately. Norway: With “anticipated” instead of “found”. Japan: As expressed in the WG, Japan supports option 2. RINA: With regards to Norway’s proposal which modifies the text with options for [found] [anticipated] it is difficult to understand how ship designers are going to know when a ship will capsize and sink without carrying out calculations. This is also the line previously taken by France. It is recognized that there are many cargo ships greater than 80 m in length, where designs vary from the traditional general cargo ship i.e. dedicated car carriers; research ships; supply ships, etc . Therefore it is considered that intermediate stage flooding should apply to both cargo and passenger ships and modify Para 7.2.2 as previously proposed:

“The factor sintermediate,i is applicable only to passenger and cargo ships (for cargo ships sintermediate,i should be taken as unity) and shall be taken as the least of the s-factors obtained from all flooding stages including etc”

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Denmark: Leave it up to the Administration to decide. UK: Considering the ease of running such calculations now, both passenger and cargo vessels must be treated the same way. Therefore the opening sentence may be modified to reflect this. France: France prefers to leave the text as it is, until we are convinced that intermediate stages of flooding are absolutely necessary also for cargo ships. Round 6 Discussion: Two members fully support Norway’s proposal requiring intermediate stage flooding to be calculated for vulnerable cargo ships whereas 6 favour no change to the current regulation and EN (which leaves the decision as to whether or not further investigation of stage flooding is needed to the Administration). Vanuatu supports Norway but shares Spain’s concern that if the proposal is adopted we will need to make a distinction between the terms “capsize” and “sink”. RINA supports Norway in principle saying that there may be a large variety of ship types with L > 80 m under the “cargo ship” category, some of which may be vulnerable to stability loss during stage flooding. However, RINA cannot see how it is possible to tell in advance without doing calculations whether a particular design will be vulnerable (therefore favouring “found” rather than “anticipated”, in contrast to Norway, who prefers “anticipated”). The UK considers that passenger and cargo vessels should be treated in the same way thereby supporting Norway in principle. Spain supports Norway in general (apart from the expression “capsize and sink”) but points out that the formula for sint may need to be revised (see under Q31D, above). If this is not possible, Spain proposes that we should add a sentence from MARPOL (see text under “Spain” above). However, the text seems very similar to what we already have in current EN (9) (If the Administration considers that the stability in intermediate stages of flooding in a cargo ship may be insufficient, it may require further investigation thereof). France prefers to leave the text and EN alone until we are convinced that stage flooding for cargo ships is absolutely necessary. SUMMARY:Fully support Norway: Finland, US, Norway, UK Would support amended proposal: Vanuatu, Spain, RINA Leave things as they are: Japan, China, Denmark, Germany, Italy, MI, France So we have 7 who favour some sort of change and 7 who don’t! PROPOSAL: As the result leaves us divided we will need to take the matter back to SLF 54. In the meantime it would seem from comments by Spain and others that Norway’s proposal to amend reg. 7-2.2 as shown below and remove EN 9 would need further consideration:_________ 2 For passenger ships the factor sintermediate,i is taken as the least of the sfactors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:

where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. sintermediate,i = 0, if the intermediate heel angle exceeds 15º. For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is [found] [anticipated] that the ship would [capsize and sink] during the

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intermediate stages, in which case sintermediate,I is taken as 0. [For passenger and cargo ships], where cross-flooding fittings are required, the time for equalization shall not exceed 10 min.” _________ For example, some suggest we may need to include a separate formula for cargo ships perhaps with different values for 0.05 and 7 and/or a new “K” factor as proposed by France in Q31D, above. We also need to resolve the square bracket issues. Would Norway accept, for example, the point made by several delegates that it is not realistic to predict how the vessel will respond to stage-flooding without performing full calculations? Or, was it Norway’s intention that a new formula or extensive calculations would not be necessary because sint for cargo ships would either be 0 (if θmax is 30 degrees or more, for example) or 1 (in all other cases)? The co-ordinators therefore propose that it would be best at this stage to ask Norway and her supporters to further clarify the original proposal and submit a revised text for re-consideration by the CG and the SLF 54 WG. Q32D (for Round 6 questionnaire). To try to resolve these issues at SLF 54 do you accept the co-ordinator’s proposal in the last sentence of the discussion paper that it would be best at this stage to ask Norway and her supporters to further clarify the original proposal and submit a revised text for re-consideration by the CG and the SLF 54 WG? RINA, Finland, Norway (with comment), Poland, US, Italy, UK, France, Yes? Denmark Germany, China No? If No, would you still prefer to leave the Reg./EN as they are?

Germany (See comment), China (Agreed – leave as they are)

Any further thoughts / alternatives?:CLIA: (N/A – cargo ship issue) Norway: Since we are no longer limited by keeping the same safety level as the previous SOLAS, Norway is of the opinion that there should be no difference between cargo and passenger ships with regard to intermediate stage of flooding. However, s=0 when heel exceeds 15 degrees to cargo vessels may be evaluated. Germany: Leave reg and EN as they are, i.e. no intermediate stages to be checked for cargo vessels Poland: I agree with Norway proposed that intermediate stage of flooding should also be considered for some cargo ships. US: As a general supporter of the Norway proposal, we were thinking more the sint = 0 or 1 case (as capsize was the fail criteria; not 30 deg). However, we recognize that this type of approach in a SOLAS regulation is not good (as pointed out by several). Therefore, if there is not clear support for a full intermediate stage requirement for cargo ships at SLF 54 then we think it is probably best to just stay with the current approach and EN. Q32: FURTHER DISCUSSION IS NEEDED AT SLF 54 [Co-ordinator’s Note: Norway has proposed that reg. 7-2.2 should take more account of IS flooding on cargo ships. We have a revised text for this change but Norway has

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been asked to clarify the proposal as support is not unanimous. The current revised text is:2 For passenger ships the factor sintermediate,i is taken as the least of the sfactors obtained from all flooding stages including the stage before equalization, if any, and is to be calculated as follows:

where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. sintermediate,i = 0, if the intermediate heel angle exceeds 15º. For cargo ships the factor sintermediate,i is taken as unity, except in those cases where it is [found] [anticipated] that the ship would [capsize and sink] during the intermediate stages, in which case sintermediate,I is taken as 0. [For passenger and cargo ships], where cross-flooding fittings are required, the time for equalization shall not exceed 10 min.] [In the 2011 CG, 9-2 were in favour of Norway producing new text; Germany and China oppose; Norway and US have comments.] [How we answer this question could also affect the EN (originally reg. 7-2.2 EN 9) for cargo ship IS flooding.] [Q34] Discuss at SLF 54 Regulation 7-2.2 Intermediate stages of flooding 1. The case of instantaneous flooding in unrestricted spaces in way of the damage zone does not require intermediate stage flooding calculations. Where intermediate stages of flooding calculations are necessary in connection with progressive flooding, or flooding through non-watertight boundaries [CLIA Q7 – accepted at SLF53]they should reflect the sequence of filling as well as filling level phases. Calculations for intermediate stages of flooding should be performed whenever equalization is not instantaneous, i.e. equalization is of a duration greater than 60 s. Such calculations consider the progress through one or more floodable (non-watertight) spaces. Bulkheads surrounding refrigerated spaces, incinerator rooms and longitudinal bulkheads fitted with nonwatertight doors are typical examples of structures that may significantly slow down the equalization of main compartments. Regulation 7-2.2 EN 1 (Add reference to flooding through non-WT boundaries) Comments received from CLIA/CCSF between round 1 and 2:

CLIA Q7 A number of clarifications with regard to progressive, sequential and cross flooding have been made for the application of the rules.

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1. The case of instantaneous flooding in unrestricted spaces in way of the damage zone does not require intermediate stage flooding calculations. Where intermediate stages of flooding calculations are necessary in connection with progressive flooding [or non-watertight boundaries], they should reflect the sequence of filling as well as filling level phases. Calculations for intermediate stages of flooding should be performed whenever equalization is not instantaneous, i.e. equalization is of a duration greater than 60 s. Such calculations consider the progress through one or more floodable (nonwatertight) spaces. Bulkheads surrounding refrigerated spaces, incinerator rooms and longitudinal bulkheads fitted with non-watertight doors are typical examples of structures that may significantly slow down the equalization of main compartments. Coordinator’s Comments: CG Member’s Comments?:Germany: Yes. Finland: Support. Italy: Agreed. France: In order to clarify the sentence, we propose : Where intermediate stages of flooding calculations are necessary in connection with progressive flooding [or flooding through nonwatertight boundaries], they should reflect…. US: We can accept this proposed change. Round 2 Discussion:- All those who replied were in support of CLIA’s amendment but France proposed a further clarification (underlined above) which seems to improve the text. CLIA Q7 (for SLF53 WG). Can we accept CLIA’s proposal, as amended by France, to change reg. 7-2.2 EN 1? Yes No Further Comments / Alternatives?:Post SLF 53 Comment:- The amendment to the EN by CLIA as modified by France was agreed in the WG (see above). CLIA Q7 AGREED AT SLF 53 Flooding boundaries 2. If a compartment contains decks, inner bulkheads, structural elements and doors of sufficient tightness and strength to seriously restrict the flow of water, for intermediate stage flooding calculation purposes it should be divided into corresponding nonwatertight spaces. It is assumed that the non-watertight divisions considered in the calculations are limited to “A” class fire-rated bulkheads and do not apply to “B” class fire-rated bulkheads normally used in accommodation areas (e.g., cabins and corridors). This guidance also relates to regulation 4.4. For spaces in the double bottom in general only main longitudinal structures with a limited number of openings have to be considered as flooding boundaries. [CLIA Q8 – accepted at SLF53] Regulation 7-2.2 EN 2 (Clarification of DB flooding boundaries) Comments received from CLIA/CCSF between round 1 and 2:

CLIA Q8 Regulation 7-2.2 EN 2 2.

If a compartment contains decks, inner bulkheads, structural elements and doors

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of sufficient tightness and strength to seriously restrict the flow of water, for intermediate stage flooding calculation purposes it should be divided into corresponding non-watertight spaces. It is assumed that the non-watertight divisions considered in the calculations are limited to “A” class fire-rated bulkheads and do not apply to “B” class fire-rated bulkheads normally used in accommodation areas (e.g., cabins and corridors). This guidance also relates to regulation 4.4. Additional explanation: For spaces in the double bottom in general only main longitudinal structures with a limited degree of openings have to be considered as flooding boundaries. Coordinator’s Comments: Would suggest using “number” rather than “degree”? CG Member’s Comments?:MI: Concur with proposal. Germany: Degree is more precise, as the ratio of opening compared to the total area is important and not the number of openings. Finland: Support “degree”. Japan: Supports comments of CLIA/CCSF and the coordinator. France: This additional explanation is useful. Correction suggested by coordinator is acceptable. The problem may be that there may be several longitudinal webs. In case of symmetrical compartment, most penalising assumption will be to split the compartment in way of the axial web. CLIA: “Degree of opening” reflects the situation better. It is not the number of openings that is relevant, but the relationship between opening area and total area. UK: Agreed. US: We are not in favour of this proposed change. Round 2 Discussion:- Of those who commented, there is good support for CLIA’s proposal but the US is not in favour. A slight majority of those in favour prefer the original CLIA text rather than replacing “degree” with “number”. As support for the proposal is not unanimous we will take the issue to SLF 53 to allow the other members to express their opinion. CLIA Q8 (for SLF53 WG). Can we accept CLIA’s proposal to change reg. 7-2.2 EN 2? Accept CLIA’s proposal? If yes, do you prefer “degree” or “number”? Further Comments / Alternatives?:Post SLF 53 Comment:- The amendment to the EN by CLIA was agreed in the WG (see above), with members preferring to use “limited number of openings” rather than “limited degree of openings”. CLIA Q8 AGREED AT SLF 53

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Sequential flooding computation 3. For each damage scenario, the damage extent and location determine the initial stage of flooding. Calculations should be performed in stages, each stage comprising of at least two intermediate filling phases in addition to the full phase per flooded space. Unrestricted spaces in way of damage should be considered as flooded immediately. Every subsequent stage involves all connected spaces being flooded simultaneously until an impermeable boundary or final equilibrium is reached. If due to the configuration of the subdivision in the ship it is expected that other intermediate stages of flooding are more onerous, then those should be investigated. R7-2.2 EN3 (Use of added weight method in IS flooding) Comments received from CLIA/CCSF between round 1 and 2:

CLIA Q9 Regulation 7-2.2 EN 3 3. For each damage scenario, the damage extent and location determine the initial stage of flooding. Calculations should be performed in stages, each stage comprising of at least two intermediate filling phases in addition to the full phase per flooded space. Unrestricted spaces in way of damage should be considered as flooded immediately. Every subsequent stage involves all connected spaces being flooded simultaneously until an impermeable boundary or final equilibrium is reached. If due to the configuration of the subdivision in the ship it is expected that other intermediate stages of flooding are more onerous, then those should be investigated Additional explanation: The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. The calculation of the intermediate filling phases should be carried out using the “added weight” method, resulting in more than one free surface.

Spaces flooded during intermediate flooding phase

Coordinator’s Comments: See discussion for Q27A regarding use of added weight method. CG Member’s Comments?:Germany: Yes.

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China: Support. Finland: Support. Italy: Agreed. France: France had proposed more precise proposals which had not been retained concerning intermediate stages. See comments in Q27A for intermediate phases. US: Although this needs further discussion, we generally support this additional explanatory text. Round 2 Discussion:- There is good support for these enhancements to the EN which overlap to some extent with a new proposal for an EN to reg 7.3 and/or 7.6 (see Q27B), which attempts to include France’s suggestion on intermediate phases. We would welcome more suggestions from France on intermediate stages to clarify this EN further. It is suggested that we take this to the WG for further discussion and to obtain the views of other members. CLIA Q9 (for SLF53 WG). Can we accept CLIA’s proposed additions to reg. 7-2.2 EN 3? Accept CLIA’s proposal? Further Comments / More improvements?:Post SLF 53 Comment:- The amendments to the EN by CLIA, including the proposed diagrams, were not agreed to by the WG. No changes needed. CLIA Q9 NFA AT SLF 54 Cross-flooding/equalization 4. In general, cross-flooding is meant as a flooding of an undamaged space on the other side of the ship to reduce the heel in the final equilibrium condition. In general, cross-flooding is used to reduce heel in the final equilibrium situation in order to improve survivability following [asymmetrical] damage. It is achieved by allowing flood water to cross into an undamaged watertight space on the other side of the ship through a special device such as a pipe or duct. Typical examples of such cross-flooding devices are shown below where the after wing tanks are connected via a cross-flooding pipe and the forward double bottom wing void spaces are connected via a cross-flooding duct. In general, cross-flooding is used to reduce heel in the final equilibrium [situation] [stage of flooding] in order to improve survivability following [asymmetrical] damage. It is achieved by allowing flood water to cross into an undamaged watertight space on the other side of the ship through a special device such as a pipe or duct. Typical examples of such cross-flooding devices are shown below where the after wing tanks are connected via a cross-flooding pipe and the forward double bottom wing void spaces are connected via a cross-flooding duct. [CLIA Q10D(1)][Do we accept the new changes in green? The changes in grey and the diagram below were accepted at SLF 53. Will the diagram be clear when printed in black and white?] [Voting 11-2 in favour of changes in green; Italy China oppose; France has comments; discuss at SLF 54. See below for full discussion leading up to round 6. ]

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R 7-2.2 EN 4 (cross-flooding) CLIA Q10 (for SLF53 WG). Can we accept the proposed amendments and additions to reg. 7-2.2 EN 4 as shown in the round 2 discussion in the working document? Post SLF 53 Comment:- The amendments to EN 4 proposed in the Round 2 discussion, originating from CLIA and France, were finally agreed to by the WG, as was inclusion of a new diagram (see above). The 2011 SDS CG may wish to consider whether we need to include the word “asymmetrical” where shown in square brackets, in the above new text. CLIA Q10C (for Round 4 questionnaire). Should we add “asymmetrical” to the revised text of EN 4 as shown in square brackets in the grey highlight above? Yes Vanuatu, US, Japan, China, Denmark, Germany, Finland No

Sweden, RINA, Italy, EC (the text is clear as it stands), UK (not sure if this actually brings any benefit over the current text), CLIA (no real need), MI (No, adding 'asymmetrical' is superfluous since the whole concept of probabilistic damage stability is asymmetrical).

Further Comments?:US: In the first sentence, the term “final equilibrium situation” is unconventional. Suggest “final equilibrium stage of flooding” (this seems generally consistent with terminology in reg 7-2.1.1 and 7-2.2). Sweden: Already implied. Norway: No comments. Italy: “Asymmetrical” is not correct when calculations are made according to resolution MSC.245(83) in case of down-flooding. France: If cross flooding is restricted to heel correction, it should apply only in case of asymmetrical flooding, but it is not necessary to specify it. From our opinion more general wording should have been adopted. In practice, this interpretation is not in line with the new interpretation allowing alternative method by time domain flooding simulation which is presented in a more general wording. Round 6 discussion: There are 7 in favour and 8 (with France) against the coordinator’s proposal to include “asymmetrical” where shown. We can easily accept the slight majority decision and keep the wording more general as Italy and France prefer. However, the US has a new issue and prefers the use of “stage of flooding” in the

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opening sentence instead of “situation” for reasons of consistency with other regulations. We therefore propose that EN 4 should now read as follows, as highlighted in green:In general, cross-flooding is used to reduce heel in the final equilibrium [situation] [stage of flooding] in order to improve survivability following [asymmetrical] damage. It is achieved by allowing flood water to cross into an undamaged watertight space on the other side of the ship through a special device such as a pipe or duct. Typical examples of such cross-flooding devices are shown below where the after wing tanks are connected via a cross-flooding pipe and the forward double bottom wing void spaces are connected via a cross-flooding duct. CLIA Q10D(1) (for Round 6 questionnaire). Can you accept the changes highlighted in green above? Japan, CLIA, RINA, Finland, Norway, Germany, US, UK, EC, Denmark Yes? France (but see comment) Italy, China No? Further Comments?:France: France is always of the opinion that a more general wording should be adopted so that for any progressive flooding which may improve the ship situation (higher s factor), justification of cross-flooding time must be done. Otherwise, situation before cross-flooding should be considered as a “final stage” for s factor calculation. CLIA Q10D(1) DISCUSS AT SLF 54

R 7-2.2 EN 4 (cross-flooding) CLIA Q10 Comments received from CLIA/CCSF between round 1 and 2: Regulation 7-2.2 EN 4 4. In general, cross-flooding is meant as a flooding of an undamaged [watertight] space on the other side of the ship [through a special device like a pipe or duct] to reduce the heel in the final equilibrium condition. Additional explanation: Typical examples for cross-flooding devices are pipes to connect wing tanks or small cofferdams to connect both sides of a void space in the double bottom

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Alternatively to the procedure as described above a time-domain flooding simulation may be carried out to assess the smallest values of sintermediate or sfinal. Coordinator’s Comments: If accepted we would recommend changing the last sentence slightly: [Alternatively] [As an alternative] to the procedure [as] described above, a timedomain flooding simulation may be carried out to assess the smallest values of sintermediate or sfinal. CG Member’s Comments?:Germany: Yes. China: Up to now not enough evidence of successful computer software of time-domain flooding which can do this simulation. How can the administration assess and recognize such software and its calculation results? Finland: Support. Italy: Agreed. France: “In general cross flooding device is meant to flood an undamaged space in order to improve survivability of the ship for the damage case.” Existing text would remain after : “The cross flooding time should be calculated ….. In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in paragraph 1.1 should be the minimum of sfinal at 10 min or at final equalization.” Additional paragraphs : “If no justification of cross flooding time is given, survival factor is calculated as sfinal for situation before equalization.” “Alternatively to the procedure as described above, a time-domain flooding simulation may be carried out to assess the smallest values of sintermediate (for situations within 600s) or sfinal (for situation after 600s).” CLIA: Agree. UK: Agree with the Coordinator’s Comments. US: We generally support the proposed changes and additional explanatory text.

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Round 2 Discussion:- There is good support for these proposals (6 in favour). France suggests an alternative to EN 4 and 2 extra paragraphs after EN 8. China raises the important issue of how administrations are supposed to validate and approve time-domain simulations. Some process of bench-marking the computer software used by industry would seem to be necessary before we can include this as an alternative. In looking again in more detail at the current EN 4, with the alternatives proposed by CLIA and France, we wondered whether it could be changed as follows to combine the best of both alternatives:4. In general, cross-flooding is used to reduce heel in the final equilibrium situation in order to improve survivability following [asymmetrical] damage. It is achieved by allowing flood water to cross into an undamaged watertight space on the other side of the ship through a special device such as a pipe or duct. Typical examples of such cross-flooding devices are shown below where the after wing tanks are connected via a cross-flooding pipe and the forward double bottom wing void spaces are connected via a cross-flooding duct. …. Insert diagram New EN 9. If no justification for cross-flooding time is provided, the survival factor is to be calculated as sfinal for the situation before equalization.” New EN 10. As an alternative to the procedure described above a time-domain flooding simulation may be carried out to assess the smallest values of sintermediate (for situations within 600s) or sfinal (for situation after 600s).” Renumber EN 9 to EN 11 This still leaves the question raised by China as to whether we should allow the use of time domain simulations if some administrations are at present unable to verify them. CLIA Q10 (for SLF53 WG). Can we accept the proposed amendments and additions to reg. 7-2.2 EN 4- 8 as shown in the round 2 discussion above? If so, should we include new EN 10 suggesting the alternative of using time-domain simulation? Accept CLIA/France proposals as amended? If yes, should we include new EN 10? Further Comments / Alternatives?:Post SLF 53 Comment:- The amendments to EN 4 proposed in the Round 2 discussion, originating from CLIA and France, were finally agreed to by the WG, as was inclusion of a new diagram (see above). The 2011 SDS CG may wish to consider whether we need to include the word “asymmetrical” where shown in square brackets, in the above new text. The proposed new EN 9 (see Round 2 discussions) was not accepted by the WG but proposed new EN 10 was accepted (see Round 2 discussions and new text inserted where appropriate below). We have now noticed that we have a sub-heading “Cargo ships” just before EN 9 so perhaps we need to re-number new EN 10 as EN 9 and renumber existing EN 9 as EN 10 (see below for clarification)?

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CLIA Q10C (for Round 4 questionnaire). Do you agree with inserting new EN 9 as shown above and the re-numbering of old EN 9 as EN 10? Yes US (see comment), Norway, Japan, RINA, Denmark (with comment), France, Germany, Finland, Italy, UK, CLIA, MI, Spain No

Vanuatu, China

Further Comments?:US: Based on our comments/proposals in Q33C above (also repeated below), we believe some modification of new EN 9 is needed (i.e. deletion of the sintermediate (for situations within 600s) or text). We do agree with the reordering of these 2 ENs. Repeated from Q33C: EN 6 for reg 7-2.2 does not seem consistent with regulation 7-2.1.1 (i.e. according to reg 7-2.1.1 it is not the smallest value of sintermediate or sfinal, as is indicated in EN 6). In addition, an EN in this context seems unnecessary (i.e. the “normal” case that is compliant with the 10 minute time limit in reg 7-2.2) and should be deleted. Then we propose combining EN 7 and 8 as follows: In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in regulation 7-2.1.1 should be the minimum of sfinal at 10 min or at final equalization. The sfinal at10 min is calculated for the floating position achieved after 10 min of equalization. This floating position is computed by calculating the amount of flood water according to resolution MSC.245(83) using interpolation, where the equalization time is set to 10 min, i.e. the interpolation of the flood water volume is made between the case before equalization (T = 0) and the total calculated equalization time. Note: it is questionable whether the approach in EN 7 and 8 are actually permitted by reg 7-2.2 RINA: Intermediate stage flooding should be considered for cargo ships see RINA response to Q32C Denmark: Though positive for the approach the validation and benchmarking of the available time domain simulations packages is a concern. Finland: Refer also to MSC 245(83) par 4, which allows time-domain simulations as an alternative method. Also instantaneous flooding (below 60 seconds) could be allowed to verify alternatively with time domain method. Round 6 Discussion: We have a large majority (13-2) in favour of inserting the new EN 9 and re-numbering old EN 9 as EN 10 under the “cargo ships” sub-heading as highlighted in grey above. We have included the US proposals as a new question (Q67D, above) and, if accepted, this would change new EN 9 and affect the numbering. RINA’s comments are dealt with under new Q32D, above. We thank Finland for bringing our attention to paragraph 4 in MSC.245(83), indicating that IMO has already accepted, in principle, the use of CFD, time domain simulations or model testing as an alternative. We share Denmark and China’s concerns about benchmarking and how Administrations are expected to approve these alternative submissions but it seems that we must accept that they are now permissible under MSC.245(83). Before concluding this question we must await the outcome of our discussions on Q67D which gives us a chance to ask you whether you think we should also include CFD and model-testing in new EN10, for consistency. CLIA Q10D(2) (for Round 6 questionnaire). As we await the outcome of Q67D, can we in the meantime ask whether you think we should include CFD and model testing as extra alternatives in new EN 10 for consistency with MSC.245(83) para. 4?

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Yes No

Japan, CLIA, RINA (see comments), Finland, Germany, US, Italy, Denmark, UK, France (see comment) China (see comment)

Further Comments?:RINA: It is concluded that at this time the procedures for CFD or model testing are not currently available; therefore they will not be available when this round of EN amendments is completed. If this is the case then it is concluded that these procedures will be submitted as new MSC work items. France: From our memories, this paragraph has been adopted at SLF 53? China: Model testing may be an option. CLIA Q10D(2) TEN MEMBERS SUPPORT INCLUSION OF CFD OR MODEL TESTING. CHINA OPPOSES. RECOMMEND ACCEPTANCE OF THE FOLLOWING AMENDMENT AT SLF 54 ON A MAJORITY VOTE: 9. As an alternative to the procedure described above a time-domain flooding simulation [,computational fluid dynamics (CFD) or model testing][CLIA Q10D(2); 10-1 in favour; recommend change]may be carried out to assess the smallest values of [sintermediate (for situations within 600s) or][US propose deletion, see Q33C] sfinal (for situation after 600s). US TO CONFIRM REQUEST FOR ABOVE-MENTIONED DELETION AT SLF 54 5. The cross-flooding time should be calculated in accordance with the Recommendation on a standard method for evaluating cross-flooding arrangements (resolution MSC.245(83)). If complete fluid equalization occurs in 60 s or less, it should be treated as instantaneous and no further calculations need to be carried out. Additionally, in cases where sfinal = 1 is achieved in 60 s or less, but equalization is not complete, instantaneous flooding may also be assumed if sfinal will not become reduced. In any cases where complete fluid equalization exceeds 60 s, the value of sintermediate after 60 s is the first intermediate stage to be considered. Only passive open cross-flooding arrangements without valves should be considered effective for instantaneous flooding cases. Regulation 7-2.2 EN paragraph 5 (ref. SLF 52/17/1 – Germany) 1 This document wishes to recall the need for uniform application of the probabilistic provisions and refers, in particular, to the cross-flooding calculation as required by SOLAS regulation II-1/7-2 (resolution MSC.216 (82)). 2 A specification of the calculation procedure is given in the EN on SOLAS regulation II-1/7-2.2, paragraph 5 of which reads: “In any cases where complete fluid equalization exceeds 60 s, the value of sintermediate after 60 s is the first intermediate stage to be considered….” Background 3 More and more damage cases will not lead to symmetric flooding scenarios. In those, cross-flooding may be the reliable measure to achieve residual stability margins, which, if proven to result in favourable s-values, can be taken into account in the summation of the attained subdivision index. 4 SOLAS provisions as supported by the EN do not provide for the degree of clarity needed for the calculation of cross-flooding arrangements, as might be deemed necessary.

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5 Germany understands that it was not intended when the related regulations were developed to consider the floating position after 60 seconds of equalization as the first intermediate stage, as resolution MSC.245(83) (Recommendation on a standard method for evaluating cross-flooding arrangements) is based on the assumption that the damaged compartments are flooded completely before equalization starts. 6 It is Germany’s view that the consideration of the first intermediate stage after 60 seconds as per regulations II-1/7-2 is not the most conservative approach with respect to ship safety. Proposal 7 Germany proposes that at the first intermediate stage it should be assumed that the damaged compartment(s) have been flooded and no equalization through cross-flooding has yet occurred. Regulation 7-2.2 EN 5 and MSC.245(83) (first intermediate stage not the worst?) . Q33. Do you agree that, at the first intermediate stage, no equalization via crossflooding has yet occurred? If so, should 7-2.2 EN5 be modified? Yes China, Germany, MI, Norway, Spain, Denmark, US No

Finland, Japan, CLIA, Italy, UK

Comments / Alternatives / Proposals for Modification?:China: The original text of EN in MSC.281(85) for the first stage of flooding for cross-flooding arrangement is too complicated and Germany’s proposal simplifies the calculation. China supports Germany. Japan: This sentence should be kept consistent with the case of after 10 minutes of equalization (Regulation 7-2.2 EN paragraph 7.7). Norway: The interpretation in 7-2.2 EN5 is in conflict with the definition of “flooding stage” in 7-2.1 and needs to be modified. Italy: Did not support document 52/17/1 by Germany. It is recalled that the text of this Explanatory Notes was the result of a joint proposal from ITALY and FINLAND, agreed in the previous ISCG Questionnaire (EN Circular 3) by a large majority (9 in favour, and only 1 contrary). It is also underlined that the current interpretation avoids unrealistic discontinuities in the calculation process. Denmark: Regarding point 4, we agree that the SOLAS and EN needs to provide more clarity and also whether cargo vessels and passenger vessels should be subject to the same standard with respect to cross and intermediate stage flooding. UK: We consider that until the issue of transient flooding is also addressed no further modification is needed. As it was shown in the past and considered in the early development of the harmonized regulations, the transient stages of flooding can have a substantial impact on vessel stability, primarily due to “multiple free surfaces”. US: Regulation 7-2.2 EN5 should be modified. France: (comments added after Round 2) Proposed formulation is more simple, but the problem is the definition of “damaged compartments” which is based on the room definition adopted for calculations. Definition of compartment may be based on flooding calculation. For large compartment extending over ship axis with connection of restricted area between two parts, it may be necessary to justify that complete flooding will occur in less than 60s. If flooding occurs in more than 60s, compartment must be split in two rooms. With proposed wording, there will be a gap in the calculation assumption if flooding time extends from 60 to 61s which is not satisfactory. The intent of present wording is to have a progressive approach, but this approach is effectively more complex.

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Round 1 Discussion: Opinion is fairly evenly divided on this issue with 7 in favour and 5 against Germany’s proposal to designate the first intermediate stage of flooding as the moment when the damage compartment has been flooded but equalization has not yet commenced. As coordinators, we have some difficulties with Germany’s proposal – for example point 6 suggests that in Reg 7-2 the first intermediate stage of flooding occurs after 60 seconds but we cannot see this written anywhere. To us, the combination of Reg 7-2, EN5 and MSC.245(83) in their present form make some sense:1) According to the definitions in Resolution MSC.245(83) paragraph 1:: Angle before commencement of cross-flooding. This assumes that the cross-flooding device is fully flooded but that no water has entered into the equalizing compartment on the opposite side of the damage (see appendix 1).

that is - when a room is damaged, floodwater is assumed to instantly fill it and the cross-flooding pipe or duct up to the entry point into the receiving space. This could be called the first stage of flooding in accordance with the definition of “flooding stage” in Reg 7-2. It is not associated with any time scale; in MSC.245(83) this stage is assumed to occur instantly and is given the designation T=0 in EN7. It is not the first intermediate stage of flooding - this may occur later. 2) Cross-flooding time is then calculated as the time it takes to fill the receiving space from that “first stage” (T=0) until equilibrium is achieved. If this takes longer than 60 s, then the status of the ship after 60 seconds is calculated and this is designated as the first intermediate stage. If it takes less than 60 seconds, flooding is assumed to be instantaneous with “sintermediate, i” determined as described in EN5. 3) EN 6 and 7 then describe what happens during the next 10 minutes where final equalization, if not already reached instantaneously or within 60 s, is either achieved or not. . Q33A. Do you agree with points 1-3 in the discussion above that Reg 7-2.2, EN5 and MSC.245(83) already give a sufficiently clear picture of how to treat crossflooding or do you think that further clarification is needed? No MI (concur), Finland, Italy, Japan, CLIA, UK, Sweden changes needed Changes Germany, China, France (with comments), Norway (with comment), US needed (with comment), Denmark Comments / Alternatives / Proposals for Modification to Reg. 7-2.2 or EN?:Germany: Germany is still of the opinion that discrepancies between SOLAS, EN and MSC.Res.245 exist. We try to explain the background in form of a sample. SOLAS allows “active cross-flooding devices” i.e. manual action by a crew member is needed to open a valve or similar. For such case it is logical that a damage stage exists which only includes the initial damaged rooms and no cross flooding at all can be considered. Having this in mind the same principle should be applied for “passive cross-flooding devices” which act automatically for the following reason •

The size of a damage acc. to SOLAS2009 (based on compartment limits) is in most cases considerably bigger than the effective diameter of the cross-flooding device. Therefore the amount of water volume that has already passed the flooding duct should be considered negligible (safe side approach)

•

Acc. to MSC.Res.245 the basis for the calculation of cross flooding time is a damage cases which does not account any cross flooding

For these reason we propose to apply the principle as laid down in SLF52/17/1 and incorporate

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this to the EN. China: The pictures in figure 1 of appendix 1 of MSC.245(83) are too small to clearly see the text on it, China has very big difficulty in developing the program code. This figure should be redrawn to be as clear as possible. France: Considering discussions on the subject, it appears that regulations or explanatory notes are not enough clear. Problem is the definition of the first intermediate stage and our understanding is the following : In explanatory notes it is said that “unrestricted spaces in way of damage should be considered as flooded immediately” which will correspond to the first intermediate stage. However the fact that a space is “unrestricted” should be justified by verifying that it is completely flooded within 60s. Otherwise for calculations, it should be split in several rooms flooded at different stages. Alternative proposal in explanatory notes is to consider that the first intermediate stage corresponds to the situation after 60s. This supposes that a flooding simulation is achieved and incorporated in probabilistic calculation. If definition of rooms used when applying the first method corresponds to a situation where they are flooded within a time close to 60s, the two approaches should give comparable results for the first intermediate stage, but this cannot be the case for all damage cases and all initial conditions. Norway: We think the German proposal is consistent with the wording (“any” and “before”) of regulation 7-2.1. US: We do not understand your discussion regarding the distinction between the first stage of flooding in accordance with the definition of “flooding stage” in Reg 7-2.2 and the first intermediate stage of flooding (that may occur later). In cross-flooding cases (as clarified by the proposed text provided by CLIA in the prior question), we agree with Germany’s proposal that the first intermediate stage of flooding should be (the potentially worst case) where the damaged compartment has been flooded but prior to any equalization via cross-flooding. Round 2 Discussion:- Opinion is very evenly divided on the issues raised by Germany (7 supporting “no change” and 6 still considering changes to be needed). For China’s point regarding the diagrams in fig. 1 of MSC.246(83), we have produced improved versions (see under MSC.245, below). It is clear that the issues will need to be discussed at the SLF 53 WG with the help of the new diagrams. We can understand the point being made by Germany and the US that we should be attempting to find the worst case before cross-flooding starts and this will be when the room is initially damaged and there is as yet no water in the cross-flooding duct or pipe. This, however, is not how the calculation of cross-flooding time is defined according to MSC.245(83) where is the angle of heel which occurs when the damaged room and the cross-flooding pipe or duct are filled. If this is not the case then MSC.245 would need to be amended. Also, Germany’s argument is that if the damage size is large the volume of flood water will be very large in comparison with the cross-flooding pipe or duct so water will not spread “instantaneously”. However, if the pipe or duct volume is as small as Germany suggests, then whether it contains flood water or not will make very little difference to the calculation of . However, if the pipe or duct restricts flow significantly then perhaps it would be better to assume that only the damaged room(s) floods “instantaneously” and that time T=0 is set to when flow through the cross-flooding device commences. This would mean changes to MSC.245(83). Q33B (for SLF 53 WG). To start the discussions off, would you agree that the definition of in MSC.245(83) should be altered so that the angle is calculated before water enters the cross-flooding pipe or duct and that this should be designated as the “first intermediate stage” of flooding for the purpose of calculating the equalization time?

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Yes, change is needed No, changes are not needed Comments / Alternatives / Proposals for Modification?:Post SLF 53 Comment:- Germany’s proposal was not accepted by the WG. However, as it could have involved change(s) to MSC.245(83) it may not have lain within our ToR which only covers S2009 updates. We do have another issue with MSC.245(83) – improving the diagrams – and to get those changed it now appears that we will need to go through IMO procedures for amending an MSC Resolution. So perhaps that would be an opportunity for Germany to re-open the debate on the cross-flooding issue they raised here and the two items could be dealt with at the same time in another forum. Further Comments by SDS CG 2011?:Q33C (for Round 4 questionnaire); for full background see the working document:As we must follow IMO procedures and make changes to MSC.245(83) separately, 1) Do you agree that we should ask the Secretariat to initiate the process of including our improvements to the cross-flooding diagrams? 2) At present cross-flooding through the duct or pipe can be considered to be instantaneous. If Germany wishes, would you want to support them in representing their proposals to IMO to clarify the definition of “first intermediate stage” of flooding in MSC.245 (83)? Vanuatu, US, France, Norway, China, RINA, Denmark, Germany, Finland, Q1 Yes Italy, UK, Spain Japan No Q2 Yes No

US (see comment), Norway, China, Denmark, Germany, UK, Spain Vanuatu, Japan, Italy, France

Further Comments (especially from Germany on Q2):US Q2: The aim of this question is not so clear to us. If the question is whether the definition of and the associated figure in Appendix 1 of MSC.245(83) should be revised to reflect no water in the cross-flooding device (for the “before cross-flooding case”), we can agree to this. However, we view the purpose of MSC.245(83) as only providing a methodology to calculate cross-flooding times, not to provide guidance for what is the first intermediate stage of flooding. Defining/clarifying the first intermediate stage of flooding should be done in the EN. Historic note regarding MSC.245(83): The original input regarding the cross-flooding device being filled with water before commencement of cross-flooding is as follows (submitted in the SDS CG for SLF 49): “Before cross flooding: For “before cross flooding there is an anticipated closing device in front of the cross flooding pipe on the reverse ship side of the damage (see Appendix II), so that no water can flow into the equalizing compartment”. So it seems this was more of a general assumption, which was incorporated into the guidance, than anything else. ----------------------------------------------------------------------------------------

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Separate / new issue regarding cross-flooding and regulation 7-2.2 EN 6: EN 6 for reg 7-2.2 does not seem consistent with regulation 7-2.1.1 (i.e. according to reg 7-2.1.1 it is not the smallest value of sintermediate or sfinal, as is indicated in EN 6). In addition, an EN in this context seems unnecessary (i.e. the “normal” case that is compliant with the 10 minute time limit in reg 7-2.2) and should be deleted. Then we propose combining EN 7 and 8 as follows: In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in regulation 7-2.1.1 should be the minimum of sfinal at 10 min or at final equalization. The sfinal at 10 min is calculated for the floating position achieved after 10 min of equalization. This floating position is computed by calculating the amount of flood water according to resolution MSC.245(83) using interpolation, where the equalization time is set to 10 min, i.e. the interpolation of the flood water volume is made between the case before equalization (T = 0) and the total calculated equalization time. Note: it is questionable whether the approach in EN 7 and 8 are actually permitted by reg 7-2.2. Denmark: Experience using MSC.245(83) has shown that it is difficult to comply. Even if a passenger ship has u-shaped tanks cross flooding according to MSC.245(83) can take more than 60 sec. The range of responses suggests that perhaps the regulations are not as clear as they might be; leading to varying application, and therefore we would support clarification. Germany: Looking at the working document, question Q33 relates to the interpretation of the 1st intermediate stage and has been answered already by most of the delegations. A majority is of the opinion that the definition of the 1st intermediate stage has to be updated; i.e. EN 7-2.2. Germany realizes that the application of the first intermediate still allows significant different interpretations, without knowing which one is more conservative. Therefore this subject needs to be further explored within the WG. France: The basic problem is always the definition of individual rooms. If cross flooding duct is of large dimension, it has to be defined as a room. If it is demonstrated that this room is flooded within less than 60s, it can be considered as instantaneously flooded. In the example of MSC.245(83), cross flooding device is identified as a pipe with a closing device. In this case, volume of pipe may be considered as negligible, but in practice, filling of this pipe will start only when valve will be opened. It can be consider that this is an example, so there is no need to update it. Additional comment could be added in explanatory notes. Round 6 Discussion: For Q1 there is a large majority (12-1) in favour of advising the Secretariat that we consider the diagrams in Appendix 1 of MSC.245(83) need to be improved - so we will take the necessary action. We hope the honourable delegation from Japan can accept this large majority verdict? For Q2 the voting was 7-4 in favour of Germany’s original proposal relating to reg. 7-2.2 EN5 being re-considered by IMO (it being recognised that our SDS CG does not currently have the required ToR for changing MSC.245(83) even if we think this necessary). However, as shown by your responses to Q1, we must change MSC.245(83) anyway to improve the diagrams, one of which (Fig. 1(c)) relates directly to the point that concerns Germany. So the idea was that we should ask the SLF subcommittee to allow us to make further changes to MSC.245(83) to ensure that it harmonises with our agreed interpretations of cross-flooding times, first stage of flooding etc which we also may wish to change in SOLAS 2009 Reg. 7-2.2 and/or the EN’s. This may involve re-considering Germany’s original proposal (below) in another forum as it was not accepted in the SLF 53 WG:Regulation 7-2.2 EN paragraph 5 (ref. SLF 52/17/1 – Germany) 1 This document wishes to recall the need for uniform application of the probabilistic provisions and refers, in particular, to the cross-flooding calculation as required by SOLAS regulation II-1/7-2 (resolution MSC.216 (82)). 2

A specification of the calculation procedure is given in the EN on SOLAS regulation II-1/7-2.2,

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paragraph 5 of which reads: “In any cases where complete fluid equalization exceeds 60 s, the value of sintermediate after 60 s is the first intermediate stage to be considered….” Background 3 More and more damage cases will not lead to symmetric flooding scenarios. In those, crossflooding may be the reliable measure to achieve residual stability margins, which, if proven to result in favourable s-values, can be taken into account in the summation of the attained subdivision index. 4 SOLAS provisions as supported by the EN do not provide for the degree of clarity needed for the calculation of cross-flooding arrangements, as might be deemed necessary. 5 Germany understands that it was not intended when the related regulations were developed to consider the floating position after 60 seconds of equalization as the first intermediate stage, as resolution MSC.245(83) (Recommendation on a standard method for evaluating cross-flooding arrangements) is based on the assumption that the damaged compartments are flooded completely before equalization starts. 6 It is Germany’s view that the consideration of the first intermediate stage after 60 seconds as per regulations II-1/7-2 is not the most conservative approach with respect to ship safety. Proposal 7 Germany proposes that at the first intermediate stage it should be assumed that the damaged compartment(s) have been flooded and no equalization through cross-flooding has yet occurred.

Taking each of your comments in turn: US. We hope we have explained the purpose of Q2 in our opening remarks, above. We apologise for not making the intent more clear. We simply wanted to try to establish whether or not Germany wished to pursue their proposal further, if necessary as a new agenda item or in another forum, and whether other SDS CG members would support this. We entirely agree with the US that the EN (or the regs) should define the first intermediate stage of flooding – it was our mistake to suggest in the question that this should be done in MSC.245(83). In fact, we believe that it is already defined in EN 5 which states that sintermediate should be the value calculated after 60 seconds of crossflooding but only in cases where the time for complete fluid equalization exceeds 60 seconds or sfinal does not achieve a value of 1 within 60 seconds. At this point, we agree with the US, that EN 5 sentence 1 hands responsibility for calculating the time for cross-flooding over to MSC.245(83) and we also agree that this is the resolution’s primary function. From studying the resolution with the help of the clearer diagrams in Appendix 1, it seems that time zero (T=0, the commencement) for calculating the time for equalization occurs when the ship is at θo degrees as shown in Fig 1c. The impacted spaces and the cross-flooding pipe are assumed to be instantaneously filled, an assumption not mentioned in SOLAS or the EN as far as we can see. We thank the US for the historical note explaining the background to this assumption in MSC.245; it does seem a little arbitrary and may need re-visiting to harmonize better with SOLAS / EN. If the cross-flooding device is not open and passive and contains valves, it conflicts directly with the last sentence of EN5. Paragraph 2.1 of MSC.245(83) then gives a formula for calculating the total crossflooding time from T=0 until final equilibrium at angle θf degrees. If this is less than 60 seconds EN 5 states that complete fluid equalization is assumed to be instantaneous and no intermediate stage flooding calculations are needed. Also, instantaneous flooding may be assumed if sfinal achieves a value of 1 in 60 seconds or less and does not subsequently reduce. Only if equalization from T=0 is greater than 60 seconds and

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sfinal is less than 1 after 60 seconds from T=0 is stage flooding assumed to occur and the first intermediate stage of flooding is as defined above in EN 5. At this point it would seem to us that the regulations, EN and MSC.245(83) are reasonably consistent and there would be little need to further clarify or define what is meant by “first intermediate stage” - as long as we accept the “definition” of T=0 as depicted in Fig 1c. The problem arises firstly (as we think Germany has pointed out), with the assumption of instantaneous cross-flooding of the pipe or duct which could give rise to an optimistic scenario. If the cross-flooding device is a large duct, the weight of floodwater in the duct itself will help the equalization process by transferring weight to the other of the ship, as shown in fig 1c. A worst case scenario, which could happen particularly where manual cross-flooding valves are fitted, occurs where water is contained on the damaged side for a considerable time until the valve is opened. An even worse case scenario may be transient asymmetrical flooding which could result in a large water load at the outboard side of the damage space before equalisation within the damaged compartment occurs. This, rejected at Malmo in December 2003, may be something for future consideration, Secondly, we are puzzled by what seems to be an anomaly in MSC.245 whereby considerable parts of it are concerned with the fluid mechanics of flooding through ducts, friction losses, air pipe venting, factor F etc and yet fig. 1c assumes that flooding through the cross-flooding device itself is instantaneous. Therefore it appears that no account need be taken in the overall flooding calculation of the time for floodwater to pass through the duct or pipe - surely a crucial factor in duct design and general safety? Or are we missing something obvious here? France has some ideas on this (below). To the co-ordinators, and, we think, Germany for different reasons, it would therefore seem more conservative to take T=0 as the time when the damaged tank is full but the cross-flooding pipe/duct is empty. This would mean either specifying T=0 in this way in the regulations and/or in the EN and in MSC.245 (by removing the shading in the pipe in fig.1c, for example). We thank the US for raising new issues with EN 6, 7 and 8 - we will open a new question box below. Denmark advises us that calculations with U-shaped tanks using MSC.245(83) often result in T>60 secs. It would be interesting to know whether this is based on the scenario in Fig 1c or whether allowances have been made for losses through the duct. Could Denmark please let us know, if possible? If we put T=0 before the duct/pipe is crossflooded then the time to achieve equalisation would be even greater, making Denmark’s “problem” worse. Perhaps the flow rate formulae in Section 2 of MSC.245(83) are too conservative? We recall that Japan did some related research on duct and pipe flow rates recently (ref. SLF53/INF.6) and we understand that research is continuing. Could Japan possibly update us on this work? Germany still thinks that the EN 5 for 7-2.2 should be updated and that we need to decide in the WG which is the most conservative interpretation of the regulations. France makes some interesting points - arguing that if a cross-flooding duct is “large” then it could be considered as a “room” defined separately from the connected compartments in the computer model. France makes a distinction between a crossflooding pipe (as shown in the figures in Appendix 1 of MSC.245) and a duct. The volume of a pipe is so small as to be negligible and it would therefore not matter, (from the “worst case” heeling moment point of view), whether the pipe was full or empty.

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However, from the “time to equalize” point of view, we co-ordinators would guess that flow through a pipe would be slower than through a duct leading to more cases with T>60 secs (that is, if we assume T=0 before any cross-flooding occurs through the pipe). Also MSC.245 contains illustrations of friction losses through both pipes and ducts suggesting that different flow rates will apply to each type of device. It is not totally clear to us how France would determine the rate of filling of the duct – when defined as a “room”. Would this be a separate procedure from para. 2.1 of resolution MSC 245(83)? Also we don’t think that it is necessarily the case that pipes are always manually controlled with valves as, we think, France may be suggesting. SUMMARY: We invite your comments on: 1) the issue of whether T=0 should occur:(a) just before water enters the cross-flooding pipe/duct OR, (b) as is currently shown in MSC.245 fig 1c, just before water enters the opposite tank or space. For (a) allowances for friction losses in the pipe/duct would be needed when using the formulae in MSC.245(83). For (b) cross-flooding through the pipe/duct would be assumed to be instantaneous with no friction losses. 2) if you prefer 1(a) could we define T=0 in EN 5 by adding, for example, the following text as highlighted in green at the end of the first sentence? The cross-flooding time should be calculated in accordance with the Recommendation on a standard method for evaluating cross-flooding arrangements (resolution MSC.245(83)) with the commencement of the cross-flooding time being when the damaged spaces are assumed to be filled to the outside water level but the cross-flooding device is empty. 3) also, if you agree with option 1(a) then we would also need to seek permission to change fig 1c in MSC.245(83) to remove all shading in the pipe. 4) if we obtain permission from the sub-committee to change MSC.245(83) should we make it clear that the diagrams apply equally to cross-flooding ducts or other devices by changing the title and amending the arrowed reference to “crossflooding pipe” in Fig 1a of Appendix 1. 5) Do you support France’s suggestion that cross-flooding ducts should be treated as “rooms” whereas the volume of pipes can be ignored and that this should be included in the EN? We cannot really use the word “large” as it may be complicated to define so would we also need to define “ducts” in the EN? Q33D (for Round 6 questionnaire). Can you please indicate your preferences to the numbered issues raised in the above summary? Yes: Japan (supports option (a)), RINA, Norway, Denmark, China, 1) Do you support US (support option a), UK (we support the assumption for T=0 just before water enters the cross-flooding device to account for the most conservative option (a) scenario. Consequently, designers will be encouraged to implement more Y/N? Comments? effective arrangements.) No: Finland, Germany, Italy Other: France (see comments below) Yes: Finland, Germany, Italy 1) OR do you support No: Norway, US, Denmark option (b) Y/N?

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Comments? 2) If you support 1(a) do you agree to amend EN5 Y/N? 3) If you support 1(a) do we need to change fig 1c in MSC.245 Y/N? 4) Should we clarify fig 1a in MSC.245 Y/N?

Yes: Japan, RINA, Norway, US, Denmark, China, UK (to the proposed EN 5 enhancement).

5) Should ducts be treated as “rooms” Y/N?

Yes: Poland, US (conceptually) No: RINA, Norway, Denmark, Italy, China, Finland (Definitions; pipe, small duct and large duct are dependent of ship size. Administrations should decide case by case the proper definitions), Germany (no, as the boundary between a pipe or a small duct and a room cannot be defined, it is up to the administration to decide on case by case basis), UK (No, at this stage we do not think that there is any need to specify an agreed lower limit for the suggested “room” treatment of the arrangement. In reality, it is up to the flag administration to accept if the duct is large enough to consider it instantaneous anyway.) Comment: France (see below) No: Poland, US, Denmark Comment: France (see below)

Yes: Japan, RINA, Norway, US, UK, Denmark, China

Yes: Japan, RINA, Finland, Norway, Germany, Poland, US (generally), UK, France, Denmark, China No: Italy

5) If “yes” should we define “large ducts” Y/N? Further Comments:Japan: Sorry we have not finalized the updated research of friction coefficients in crossflooding yet but have a plan to submit the report (INF paper) to SLF 54. [Co-ordinator’s Note:See SLF 54/4/2 and .INF14]

CLIA: No further comments France on 1): The answer to question 1) depends on the volume of the cross flooding duct/pipe. Option “a” of 1) would apply if this volume is such that it is necessary to describe it as a room. If cross flooding pipe is not described as a room, the question is irrelevant. France on 5): Usual practice is to define volume of duct as a room only if it is made of structural elements. A clearer criterion to define if duct is large (has to be described as a room) would be to define a minimum volume by reference to ship’s moulded displacement per centimetre. For calculation of cross flooding time, if pipe is not described as a room, it will not be possible to take into account the time necessary to fill the pipe. If pipe/duct is defined as a room, its volume will be taken into account in the cross-flooded volume. If its volume remains small in comparison with cross-flooded compartment, “k” factor will be calculated for the situation after filling of the duct which is pessimistic as actual k factor

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will be less during the phase of filling of the duct. If volume of duct is large, two successive cross flooding stages will be considered with specific “k” factors. Q33 R7-2.2 EN5 Summary of outcome of Q33D on text of EN: 5. The cross-flooding time should be calculated in accordance with the Recommendation on a standard method for evaluating cross-flooding arrangements (resolution MSC.245(83)) [with the commencement of the cross-flooding time being when the damaged spaces are assumed to be filled to the outside water level but the cross-flooding device is empty]. [Q33D(2); 7 support this] If complete fluid equalization occurs in 60 s or less, it should be treated as instantaneous and no further calculations need to be carried out. Additionally, in cases where sfinal = 1 is achieved in 60 s or less, but equalization is not complete, instantaneous flooding may also be assumed if sfinal will not become reduced. In any cases where complete fluid equalization exceeds 60 s, the value of sintermediate after 60 s is the first intermediate stage to be considered. Only passive open cross-flooding arrangements without valves should be considered effective for instantaneous flooding cases. [Coordinator’s Note: linked to this is the question of possible changes to MSC.245(83), in particular the cross-flooding figures and whether the cross-flooding pipe/duct should be assumed to be flooded instantaneously. [Q33D(1) (7 in favour 3 against);(3)(7 support) (4) (11-1 in favour] and France’s proposal to treat cross-flooding ducts as rooms [Q33D(5); 2 support, 8 against]. TO BE DISCUSSED FURTHER AT SLF 54.

6. If complete fluid equalization can be finalized in 10 min or less, the assessment of survivability can be carried out for passenger ships as the smallest values of sintermediate or sfinal . 7. In case the equalization time is longer than 10 min, sfinal is calculated for the floating position achieved after 10 min of equalization. This floating position is computed by calculating the amount of flood water according to resolution MSC.245(83) using interpolation, where the equalization time is set to 10 min, i.e. the interpolation of the flood water volume is made between the case before equalization (T = 0) and the total calculated equalization time. 8. In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in paragraph 1.1 should be the minimum of sfinal at 10 min or at final equalization. R7-2.2 EN6-8 (NEW ITEM INTRODUCED BY USA IN THEIR RESPONSE TO ROUND 4 QUESTIONNAIRE)

Separate / new issue regarding cross-flooding and regulation 7-2.2 EN 6: EN 6 for reg 7-2.2 does not seem consistent with regulation 7-2.1.1 (i.e. according to reg 7-2.1.1 it is not the smallest value of sintermediate or sfinal, as is indicated in EN 6). In addition, an EN in this context seems unnecessary (i.e. the “normal” case that is compliant with the 10 minute time limit in reg 7-2.2) and should be deleted. Then we propose combining EN 7 and 8 as follows: In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in regulation 7-2.1.1 should be the minimum of sfinal at 10 min or at final equalization. The sfinal at 10 min is calculated for the floating position achieved after 10 min of equalization. This floating position is computed by calculating the amount of flood water according to

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resolution MSC.245(83) using interpolation, where the equalization time is set to 10 min, i.e. the interpolation of the flood water volume is made between the case before equalization (T = 0) and the total calculated equalization time. Note: it is questionable whether the approach in EN 7 and 8 are actually permitted by reg 7-2.2. Coordinator’s Comments: We are not totally certain about the first statement from the US as reg. 7-2.1.1 appears to us to indicate that si is to be taken as the minimum of sint or sfinal.smom which does not conflict with EN 6. However, at this stage we will simply invite general comments on the US proposals, which may need further discussion at SLF 54. For easy reference the existing EN’s 6-8 are included below:6. If complete fluid equalization can be finalized in 10 min or less, the assessment of survivability can be carried out for passenger ships as the smallest values of sintermediate or sfinal . 7. In case the equalization time is longer than 10 min, sfinal is calculated for the floating position achieved after 10 min of equalization. This floating position is computed by calculating the amount of flood water according to resolution MSC.245(83) using interpolation, where the equalization time is set to 10 min, i.e. the interpolation of the flood water volume is made between the case before equalization (T = 0) and the total calculated equalization time. 8. In any cases where complete fluid equalization exceeds 10 min, the value of sfinal used in the formula in paragraph 1.1 should be the minimum of sfinal at 10 min or at final equalization. Q67D (for Round 6 Questionnaire). Do you agree with the above statements from the US and their proposal to delete EN 6 and combine EN 7 and 8? Japan, Finland, Germany (Yes, the US proposal for EN 7 and 8 seems to be Yes clearer), US, UK, EC (At least US has a point to question the approach taken in EN 7 and 8, which do not seem to be in line with Reg. 7-2.2.), France (see comment) Italy, Denmark, China No Further Comments:Japan: Has no strong position. US: Regarding the Co-ordinator’s Comments: “We are not totally certain about the first statement from the US as reg. 7-2.1.1 appears to us to indicate that si is to be taken as the minimum of sint or sfinal.smom which does not conflict with EN 6.” We apologize that our original comment was not very clear or explicit on what we meant. All we were trying to point out is an apparent typo in that the reg 7-2.2 EN 6 indicates the smallest value of sintermediate or sfinal, but in regulation 7-2.1.1 it is the smallest value of sintermediate or sfinal.smom (i.e. product of sfinal x smom). France: If paragraph 6 is kept, it should be amended by replacing sfinal by sfinal * smom. Q67. SEVEN MEMBERS SUPPORTED THE US PROPOSAL TO DELETE EN6 AND MERGE EN7 AND 8. THREE OPPOSED AND FRANCE HAS A FURTHER COMMENT. DISCUSS FURTHER AT SLF 54

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9. As an alternative to the procedure described above a time-domain flooding simulation [,computational fluid dynamics (CFD) or model testing][CLIA Q10D(2); 10-1 in favour; recommend change]may be carried out to assess the smallest values of [sintermediate (for situations within 600s) or][US propose deletion, see Q33C] sfinal (for situation after 600s). Cargo ships [9][10]. If the Administration considers that the stability in intermediate stages of flooding in a cargo ship may be [insufficient] [Q34 awaiting outcome of Q32D], it may require further investigation thereof. [Need to discuss all these EN’s together at SLF 54 once we agree to Q32D] Regulation 7-2.2 (ref. SLF 51/3/2 Annex – US and Sweden) Stability in intermediate stages of flooding for cargo ships: Although it was decided not to include a requirement for cargo ship intermediate stage flooding calculations in regulation 7-2.2, there were views that this important issue should be revisited in the future (see SLF 47/WP.6, paragraph 6 below). “6 Several delegations believed that intermediate stages of flooding should be considered for some cargo ships and that this issue should be revisited in any future revision of the regulations. The draft text of regulation 4, paragraph 2, permits some flexibility by the Administrations and there was general support to include the following in the Explanatory Notes:

“If the Administration considers that the stability in intermediate stages of flooding may be insufficient, it may require further investigation thereof”.” [Coordinator’s Note: The underlined sentence is included in the current text of the EN]. R7-2.2 EN9 (Should reference to cargo ships remain as an EN?) . Q34. Do you think that this issue should remain fairly general, as in current Explanatory Note 9, or should it be included as an amended regulation 7-2.2 as proposed by Norway (see Q32)? Yes

(leave as EN9): China, Finland, Germany, Japan, MI, CLIA, Italy, UK, France

No

(need amendments to Reg 7-2.2): Norway, Spain, Denmark, US, Sweden

Comments / Alternatives?:China: China reserve the position that for cargo ships the stability in intermediate stage of flooding need not be considered. Norway: “insufficient” is a vague expression not suitable for an EN. Spain: Explanatory notes are not mandatory. It should be mandatory to evaluate intermediate stages of flooding for some cargo vessels. Denmark: Clear guidance as to what is considered insufficient and how it should be investigated would be preferable. US: As indicated in Q32, this issue requires further consideration. France: (comment added after Round 2) If this issue was included into regulation 7-2.2, wording should be more precise. ( see comment to Q32).

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Round 1 Discussion: As this issue has already been discussed in detail under Q32, we propose to await your responses to Q32A above which should determine our future action. Any further comments?:France: This question is linked to Q32A. Round 2 Discussion: Await response to Q32B. Post SLF 53 Comment:- This item was discussed under Q32B above and, as reported by the WG to plenary, option 2 from the Round 1 discussion notes was preferred (i.e. leave the regulation and EN unchanged, thereby allowing the Administration to decide if further investigation is needed for cargo ships). However, the WG chairman said that because of the variety of views expressed this issue could be re-opened in the 2011 CG. So, does anybody in the 2011 SDS CG have any further comments?:Q34:- For Round 4 CG, see Q32C above. CLIA Q10C, above, may also be affected by the response to Q32C, relating to stage flooding for cargo ships. Further Comments?:US: We don’t really understand the question/issue; our position is per Q32C. Norway: As mentioned in Q32 we propose changes to the regulation. However, if the regulation remains unchanged we need to change the EN due to the vague expression “insufficient” which is not suitable for an EN. RINA: Intermediate stage flooding should be considered for cargo ships see RINA response to Q32C and CLIA Q10C. Denmark: No comments. Germany: Keep EN9 as it is. Finland: EN9 shall be in line with Q32C acc. to proposal from Norway. Italy: NO FURTHER AMENDMENTS TO 7-2.2 ARE NECESSARY. Round 6 Discussion: We apologise that the question was not clear. The future of old EN9 (new EN10) depends on the outcome of Q32 as to whether or not we apply intermediate stage flooding to cargo ships: Cargo ships 9 10. If the Administration considers that the stability in intermediate stages of flooding in a cargo ship may be insufficient, it may require further investigation thereof. If, as Norway says, we decide to keep the present text of reg. 7-2.2 as being applicable only to passenger ships then new EN 10 will remain in place but it may need to be changed (for example, by clarifying “insufficient”). So it is proposed that we leave this question open pending the outcome of Q32D, which may not be resolved until SLF 54.

Q34 AWAIT OUTCOME OF Q32D AT SLF 54 BEFORE TAKING FURTHER ACTION. 3

The factor sfinal,i shall be obtained from the formula:

where:

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GZmax is not to be taken as more than 0.12 m; Range is not to be taken as more than 16°; [Coordinators Note: PLEASE NOTE ERROR IN FOLLOWING INEQUALITIES (see S2009 consolidated errata sheet)

[Should read] K = 1

if θe ≥ θmin

[Should read] K = 0

if θe ≤ θmax ]

[New Notes for Round 2: JAPAN in Round 1 thinks that the original text is correct, i.e. if θe ≤θmin if θe ≥ θmax

K = 1 K = 0

US confirms that the original formulae taken from MSC.216(82) are correct, as shown in the original text above. Both the 2009 Consolidated Edition and the accompanying errata sheet are therefore incorrect. The SLF Secretariat has been informed. Also see SLF 53/14 paragraph 12.4.] [AT SLF 54 – NFA; LEAVE IT TO SECRETARIAT] 4 The factor smom,i is applicable only to passenger ships (for cargo ships smom,i shall be taken as unity) and shall be calculated at the final equilibrium from the formula:

where: Displacement is the intact displacement at the subdivision draught; Mheel is the maximum assumed heeling moment as calculated in accordance with subparagraph 4.1; and

Regulation 7-2.4 1. The displacement is the intact displacement at the subdivision draught in question (ds, dp and dl ).

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2. The calculations should be based on the same hull form as for intact stability calculations (including appendages and shell plating). 3. The stability levers (GZ) and centre of gravity positions (KG) for judging the final survival conditions should be calculated by the constant displacement (lost buoyancy) method. 4.

The calculations should be done for the ship freely trimming. [Q35]

Regulation 7-2.4 (ref. SLF 51/3/2 Annex – US and Sweden) Clarify the item that is now addressed in the Explanatory Notes: “The displacement is the intact displacement at the subdivision draught in question (ds, dp and dl).”

Regulation 7-2.4 (ref. SLF 52/17/5 Annex – Norway) Document SLF 51/3/2 contains a request that the meaning of the first sentence, “The displacement is the intact displacement at the subdivision draught in question (ds, dp and dl )” in the EN be clarified. This Administration believes that this text must be seen in connection with paragraph 3 in regulation 7: “That is, the constant displacement method of calculation should be used.” It is proposed that these paragraphs be harmonized with the following principles in MSC/Circ.406/rev.1: “3.1 The calculations should be based on moulded lines and include large appendages such as shaft bosses, skegs and bow thrusters. 3.2 The metacentric heights (GM), stability levers (GZ) and centre of gravity positions (KG) for judging the final survival conditions should be calculated by the constant displacement (lost buoyancy) method. 3.3

The calculations should be done for the ship freely trimming.”

[Coordinators Note: The above principles can be found, for example, in the BCH Code 2008 Edition. Can Norway please confirm the MSC/Circ.406 reference? It is entitled Annex “Guidelines on Interpretation of the IBC Code and the IGC Code and Guidelines for the Uniform Application of the Survival Requirements of the IBC and IGC Codes” and does not appear to contain the text quoted?].

R7-2.4 (Clarify definition of displacement in EN) . Q35. Do you agree that the underlined text should be added to the EN, as proposed by Norway? Yes Finland, Germany, Japan, Norway, CLIA, Spain, Denmark, UK, US, Sweden No Reasons / Comments / Alternatives?:China, MI: No comments. Finland: Method how to notice free surfaces during intermediate stages and phases to be also clearly defined. This may require further studies. If damage is considered to have a very large number of intermediate stages the stability curve of the last intermediate stage must be practically the same as the stability curve of the final stage (calculated with the lost buoyancy method) since in reality the flooding is a continuous process. Also the spirit of the rule concerning the damage

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extents should not be violated. Germany: Intermediate phases have to be calculated by “added weight” method. Norway: Please note that the Norwegian paper refers to MSC/Circ.406/Rev.1, i.e. the 1990 version. The paragraphs in question will be found under “GUIDELINES FOR THE UNIFORM APPLICATION OF THE SURVIVAL REQUIREMENTS OF THE BULK CHEMICAL CODE AND THE GAS CARRIER CODE” in the annex to that document. Denmark: We support additional detail in the EN, however we note that 3.1 should probably read “shaft bossing.” Round 1 Discussion: There are 10 in favour of this proposal, 2 “no comments” and 1 no vote. Thanks to Norway for clarifying the source of the text; Denmark suggests replacing “shaft bosses” with “shaft bossing”, which seems reasonable. Finland and Germany raise interesting comments on use of the added weight method and calculation of free surfaces during intermediate stages (IS) of flooding, issues which we discuss in detail under Q27. This matter is quite complex so we will await your responses to Q27A to see how to take it further with the SLF subCommittee. If we set that to one side for now, can we then agree to Norway’s proposal on the understanding that more text may be needed later to cover the calculation of IS flooding? . Q35A. Do you agree that the underlined text should be added to the EN, as originally proposed by Norway and amended by Denmark, in the knowledge that more text may be needed later to cover IS flooding, MFS and use of added weight during IS flooding? Yes MI (agree), Germany, Finland, Italy, Japan, RINA, France (but with proposed amendments – see comments below), Norway (with comments), CLIA, UK, US, Sweden, Denmark No Comments / Alternatives?:France: 3.1 : Line should be the same as for intact stability ( normally including all appendages and shell plating,) otherwise draft in intact condition will not correspond to this calculated from hydrostatics elements. That is the usual practice. So if comment is add in explanatory notes, it should be said : The calculations should be based on the same hull form as for intact stability calculations (including appendages and shell plating) 3.2 : Comment on GM and GZ should apply to paragraph 2, 3 and 4 of regulation 7-2. For intermediate stages, added weight method has to be used ( or combination of added weight and lost buoyancy). The physical parameter is the righting moment from which is derived the GZ (GM is no more used as a criterion and anyway it may be calculated from the slope of GZ curve). So what is important to say is that GZ must be calculated (from inclining moment) assuming a constant displacement equal to intact displacement. KG is a basic data, which represent the vertical position of ship centre of gravity in intact condition. So a preferable wording applicable to all these paragraph would be : Righting levers (GZ) for judging the survival conditions should be calculate referring to the displacement in intact condition at the draft in question. 3.3 Proposed formulation is accepted. : The calculations should be done for the ship freely trimming.” Norway: Using constant displacement in this context where no initial masses are considered lost (as opposed to cargo in MARPOL etc) will normally be slightly conservative with respect to the effect on the righting lever. We are not sure if the wording in regulation 7.3 was included for this reason. Please note that our proposal and MSC/Circ.406/rev.1 relates to the “final survival conditions”. We agree that the question on whether to disregard the transient added mass in partially flooded spaces not communicating directly with the sea as well as handling of free

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surface effects in these spaces should be discussed further. Round 2 Discussion: There is full support for Norway’s proposal, as amended by Denmark. (Also see Q27B for MFS and use of added weight method for stage-flooding). France has some alternative proposals. All the proposals are repeated below for easy reference:Norway “1 The calculations should be based on moulded lines and include large appendages such as shaft [bosses][bossing], skegs and bow thrusters. 2 The metacentric heights (GM), stability levers (GZ) and centre of gravity positions (KG) for judging the final survival conditions should be calculated by the constant displacement (lost buoyancy) method. 3 The calculations should be done for the ship freely trimming.” France “1 The calculations should be based on the same hull form as for intact stability calculations (including appendages and shell plating). 2 Righting levers (GZ) for judging the survival conditions should be calculated referring to the displacement in the intact condition at the draft in question. 3 The calculations should be done for the ship freely trimming.” Proposed revisions to reg. 7.3 (see Q27B) “3 When determining the positive righting lever (GZ) of the residual stability curve [in the final stage of flooding], the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used.[During intermediate stages of flooding the added weight method should be used ].” We must say that we are now slightly confused as to whether this proposal should be fitted in as extra EN’s to reg. 7-2.4 or new EN’s to reg. 7.3 (see Norway’s comment after round 1, above) so we suggest this should be discussed at the WG. Q35B (for the SLF 53 WG). Please state (a) whether you prefer Norway’s original proposal as modified by Denmark or France’s new proposal and (b) whether your preferred proposal should appear as three extra ENs to reg. 7-2.4 or three new ENs to reg. 7.3? (a) Do you prefer proposal from Norway or France? (b) EN for reg. 7.3 or reg. 7-2.4. Comments / Alternatives?:Post SLF 53 Comment:- In the end, France’s proposals in the Round 2 discussion were favoured by the WG (with very minor modifications) - see above. Note that we have renumbered the EN’s for consistency, giving the existing EN number 1. Q35. AT SLF 54 RECOMMEND EN FOR R7-2.4 BE ALTERED AS SHOWN BELOW AS AGREED AT SLF 53:-

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Regulation 7-2.4 1. The displacement is the intact displacement at the subdivision draught in question (ds, dp and dl ). 2. The calculations should be based on the same hull form as for intact stability calculations (including appendages and shell plating). 3. The stability levers (GZ) and centre of gravity positions (KG) for judging the final survival conditions should be calculated by the constant displacement (lost buoyancy) method. 4. 4.1

The calculations should be done for the ship freely trimming. The heeling moment Mheel is to be calculated as follows: Mheel = maximum {Mpassenger or Mwind or MSurvivalcraft}

4.1.1 Mpassenger is the maximum assumed heeling moment resulting from movement of passengers, and is to be obtained as follows: Mpassenger = (0.075 · Np) · (0.45 · B) (tm) where: Np is the maximum number of passengers permitted to be on board in the service condition corresponding to the deepest subdivision draught under consideration; and B is the beam of the ship breadth of the ship as defined in Regulation 2.8. [Q36] Alternatively, the heeling moment may be calculated assuming the passengers are distributed with 4 persons per square metre on available deck areas towards one side of the ship on the decks where muster stations are located and in such a way that they produce the most adverse heeling moment. In doing so, a weight of 75 kg per passenger is to be assumed.

[Coordinator’s Note for Round 2:-: MSC.272(85), which came into force on 1st July, 2010, has increased the average passenger mass to 82.5 kg for certain LSA applications. For consistency, should we also consider increasing this figure where highlighted in yellow in Reg 7-2.4.1.1 above? The 2008 IS Code uses 75 kg as a minimum to be assumed. Comments Invited: Germany: No. the mean weight of 75kg seems still be applicable for stability calculations. Japan: Supports coordinator’s proposal to change “75 kg” to “82.5 kg”. CLIA: Consistency with the IS Code is needed, so both would need to change to 82.5 Kg. UK: The average passenger weight seems to be increasing. However, within the damage stability regulations we could consider with immediate affect adding [“as a minimum”] to promote voluntary use of larger figures for special operational conditions until such time as we are presented with a supporting data set including relevant passenger profiles for different ship sizes and types. US: We support updating the reg 7-2.4.1.1 text to reflect the increased passenger weight. (This should also be done in the 2008 IS Code.)

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Coordinator’s Note for Round 3:-: Propose we discuss this at the SLF 53 WG to obtain the

views of other members and to decide the best course of action. Post SLF 53 Note:- There was no support in the WG for increasing the assumed weight or for changing the wording, therefore leave unchanged. NFA at SLF 54. ] Regulation 7-2.4.1.1 The beam B used in this paragraph means breadth as defined in regulation 2.8. Regulation 7-2.4.1.1 (ref. SLF 51/3/2 Annex – US and Sweden) Clarify the item that is now addressed in the Explanatory Notes: “The beam B used in this paragraph means breadth as defined in regulation 2.8.” R7-2.4.1.1 (Clarification of B definition) R7-2.4.1.1 (Delete EN?) . Q36. Do you agree that further clarification of the EN is needed? Yes Norway, Denmark, Sweden No

China, Finland, Germany, MI, CLIA, Italy, UK, US

Comments / Proposed wording?:Japan: No comments. Norway: It would perhaps be a better option to delete “B is the beam of the ship” from the regulation since the definition in regulation 2.8 makes it redundant. Spain: Probably further explanation is needed. Maybe the intention is to permit the use of another beam in special cases (e.g. accommodation deckhouses with a beam significantly lower than the maximum breadth of the vessel). Denmark: We should perhaps use ‘B is the breadth of the ship as defined in Regulation 2.8’ to avoid introducing new terms. US: The definition of B in regulation 7-2.4.1.1 should be revised directly (i.e. “B is the breadth as defined in regulation 2.8”); then the EN can be deleted. Round 1 Discussion: It would seem that the best solution is to simply state in the Regulation that “B is the breadth of the ship as defined in Regulation 2.8” and remove the EN altogether. Q36A. Do you agree that we define B in the regulation using the US/Denmark’s text (‘B is the breadth of the ship as defined in Regulation 2.8’) and delete the EN as proposed by the US? Yes MI, Germany, Finland, Italy, Japan, RINA, Norway (with comment), CLIA, UK, US, Sweden, Denmark No Comments / Alternatives?:Japan does not have a strong position. France: This proposal is acceptable, but present wording of regulation + EN seems equivalent. Norway: Denmark/US proposals are OK, but we think the sentences in the regulation and the EN are redundant given the definition in 2.8. Round 2 Discussion: There is unanimous support for the additional text in the regulation as proposed by US/Denmark and for deleting the EN although Norway and France think that we could omit both anyway as “B” is already defined. It just seems that because we are defining the other term in the formula for Mpassenger (Np) it may look slightly better to define B as well?

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Q36B (for SLF 53 WG). Do you agree to change reg. 7-2.4.1.1 to read “B is the breadth of the ship as defined in regulation 2.8.” and to delete the EN? Yes No Further Comments?:Post SLF 53 Note:- The WG agreed to change Reg. 7-2.4.1.1 and delete the EN. Note that the regulation for the definition of B is now 2.7. SLF 54 Accept changes agreed at SLF 53 but ensure the cross-reference is correct, (depending on outcome of Q66). 4.1.2 Mwind is the maximum assumed wind force acting in a damage situation: Mwind

= (P · A · Z) / 9,806 (tm)

P=

120 N/m ;

where: 2

A = projected lateral area above waterline; Z = distance from centre of lateral projected area above waterline to T/2; and T = ship’s draught, di. Regulation 7-2.4.1.2 The parameter A (projected lateral area) used in this paragraph does not refer to the attained subdivision index. 4.1.3 MSurvivalcraft is the maximum assumed heeling moment due to the launching of all fully loaded davit-launched survival craft on one side of the ship. It shall be calculated using the following assumptions: .1

all lifeboats and rescue boats fitted on the side to which the ship has heeled after having sustained damage shall be assumed to be swung out fully loaded and ready for lowering;

.2

for lifeboats which are arranged to be launched fully loaded from the stowed position, the maximum heeling moment during launching shall be taken;

.3

a fully loaded davit-launched liferaft attached to each davit on the side to which the ship has heeled after having sustained damage shall be assumed to be swung out ready for lowering;

.4

persons not in the life-saving appliances which are swung out shall not provide either additional heeling or righting moment; and

.5

life-saving appliances on the side of the ship opposite to the side to which the ship has heeled shall be assumed to be in a stowed position.

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5 Unsymmetrical flooding is to be kept to a minimum consistent with the efficient arrangements. Where it is necessary to correct large angles of heel, the means adopted shall, where practicable, be self-acting, but in any case where controls to equalization devices are provided they shall be operable from above the bulkhead deck. These *

fittings together with their controls shall be acceptable to the Administration. Suitable information concerning the use of equalization devices shall be supplied to the master of the ship. _______________ *

Reference is made to the “Recommendation on a standard method for establishing compliance with the requirements for cross-flooding arrangements in passengers ships”, adopted by the Organization through resolution [A.266(VIII), as may be amended]. [MSC.245(83), on 12th October, 2007 to replace resolution A.266(VIII)].

[Coordinator’s Note:- The existing footnote in the SOLAS2009 Consolidated Edition refers to A.266 “as may be amended”. Should we now refer specifically to the new resolution “as may be amended”? MSC. 245 (83) is included below for easy reference. Comments invited:Finland: Reference to new resolution is needed. The FLOODSTAND is investigating these matters and there might be a reason to return to it later on. Germany: Reference to new resolution preferred. Denmark: Yes, we should amend this footnote for clarity. US: The footnote should reference both A.266 and MSC.245(83), as there was resistance to superseding A.266. ] [Coordinator’s Note for Round 2:- Those who responded agree that reference should be made here to the latest MSC resolution but the US would prefer references to both A.266 and MSC.245. Is it true to say that A.266 should continue to be applied to ships constructed before 1/1/2009 and MSC.245 to “new” ships built under S2009 constructed on or after 1/1/2009 and that we should make this clear in the revised footnote or was this not the intention of MSC83? Comments invited:France: It would be better to have the correct reference. UK: In the light of MSC.245(83) we do not see the need to make further clarification. US: We would like to retract our previous comment to also include A.266. As indicated in your summary, S2009 Chapter II-1 applies to ships constructed on or after 1/1/2009 and they should only use MSC.245. Therefore we now agree with the others that the footnote should be updated to only include reference to MSC.245. Note: the resolution title has also changed slightly. ] [Coordinator’s Note for Round 3:- Thank you US. So we can agree to change the footnote to read:-

_____________ * Reference is made to the Recommendation on a standard method for evaluating crossflooding arrangements, adopted by the Organization by resolution MSC.245(83), as may be amended. ]

This change to the footnote was agreed by the WG at SLF 53. ]

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RESOLUTION MSC.245(83) (adopted on 12 October 2007) RECOMMENDATION ON A STANDARD METHOD FOR EVALUATING CROSS-FLOODING ARRANGEMENTS THE MARITIME SAFETY COMMITTEE, RECALLING Article 28(b) of the Convention on the International Maritime Organization concerning the functions of the Committee, RECALLING ALSO resolution A.266(VIII) entitled "Recommendation on a standard method for establishing compliance with the requirements for cross-flooding arrangements in passenger ships", adopted by the Assembly at its eighth session, NOTING that the above Recommendation does not include provisions for cross-flooding arrangements other than pipes (i.e., cross-flooding times through ducts) or a provision to ensure adequate air ventilation for efficient cross-flooding (i.e., to account for the restrictive effect of air counter pressure during cross-flooding), NOTING ALSO the revised SOLAS chapter II-1 subdivision and damage stability requirements for passenger and cargo ships, adopted by resolution MSC.216(82), RECOGNIZING the need to establish a methodology for evaluating cross-flooding arrangements on ships subject to the applicable subdivision and damage stability requirements of SOLAS chapter II-1 to ensure uniform treatment of cross-flooding and equalization arrangements, HAVING CONSIDERED the recommendations made by the Sub-Committee on Stability and Load Lines and on Fishing Vessels Safety at its fiftieth session, 1. ADOPTS the Recommendation on a standard method for evaluating cross-flooding arrangements, the text of which is set out in the Annex to the present resolution; 2. INVITES Governments to apply the annexed Recommendation to cross-flooding calculations and to bring the Recommendation to the attention of all parties concerned.

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Resolution MSC.245(83) 12 October 2007 Page 2

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Resolution MSC.245(83) 12 October 2007 Page 3

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Resolution MSC.245(83) 12 October 2007 Page 4

[Coordinator’s Note for SLF 54:- SLF 54/4 para. 3.1 states that the formula in 2.5 above is incorrect and should read as shown in Eq. 2 of the Annex to that paper.]

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Resolution MSC.245(83) 12 October 2007 Page 5

[Coordinator’s Note for SLF 54:- SLF 54/4 para. 3.2 proposes to replace the text under “4 Alternatives”, above, with “Values for k can be obtained from appendix 2 or other appropriate sources. Also CFD (computational fluid dynamics) can be used to evaluate the discharge coefficient for the whole cross duct.” ]

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Resolution MSC.245(83) 12 October 2007 Page 6

[Coordinator’s Note:– could something be done to improve the clarity of these diagrams – increase size and turn through 90 degrees clockwise, for example? Comments? China: The diagrams on Page 6 of annex to MS.245(83) are too small, I cannot see the text

clearly. It’s better to be updated. Finland: It is desirable to improve the clarity of figures on p. 6

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CLIA: Yes. Denmark: Yes, agreed. US: Yes – if someone will volunteer to do it! ][Co-ordinator’s Note Round 2: We will try. France: Diagram could be improved, but this is not a major point.]

Post SLF 53 Note:- It was agreed that the diagrams need improving but we need to ask the sub-committee for authorization to make these changes under a new work item.]

Upper Deck

Main Deck Location of damage cross-flooding pipe Tank Top

Flooded Compartments

Equalizing Compartment

Fig 1(a) Section showing cross-flooding pipe and compartments

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Maximum allowable angle of heel for final stage of flooding

Equilibrium flooding position

hf

Hθ

Before cross flooding

H0

θf θ θ0

Fig 1(b) Different stages of cross-flooding

Before cross flooding

θ0 H0

Water on flooded side before cross flooding

Anticipated closing device

Fig 1(c) Situation after damage but before cross-flooding

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Maximum allowable angle of heel for final stage of flooding Wθ = Volume of water to bring the ship from θ to θf

θ Hθ

Water inflow until the maximum allowable angle of heel is achieved

Fig 1(d) Situation at maximum allowable angle of heel

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Equilibrium floating position Wf = Volume of water to bring the ship from θ0 to θf

hf θf Water inflow until the equilibrium floating position is achieved

Fig 1(e) Situation at final equilibrium

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Resolution MSC.245(83) 12 October 2007 Page 7

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Resolution MSC.245(83) 12 October 2007 Page 8

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Resolution MSC.245(83) 12 October 2007 Page 9

[Coordinator’s Note for SLF 54:- SLF 54/4 para. 3.3 proposes removal of figures 13 and 14 with explanations from the resolution. The paper states that the current methods in Res MSC.245(83) “may result in a significant under-estimation of the cross-flooding time ….”. See SLF 54/8/1 para 15.11 for a proposal to ask the S/C for a new agenda item to update MSC.245(83) as it is not within the current ToR of the SOLAS updates AI.]

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Resolution MSC.245(83) 12 October 2007 Page 10

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Resolution MSC.245(83) 12 October 2007 Page 11

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Regulation 7-2.5 In cargo ships where cross flooding devices are fitted, the safety of the ship should be maintained in all stages of flooding. The Administration may request for this to be demonstrated. Cross-flooding equipment, if installed, should have the capacity to ensure that the equalization takes place within 10 min. 5.1 Tanks and compartments taking part in such equalization shall be fitted with air pipes or equivalent means of sufficient cross-section to ensure that the flow of water into the equalization compartments is not delayed. 5.2 In all cases, si is to be taken as zero in those cases where the final waterline, taking into account sinkage, heel and trim, immerses: .1

the lower edge of openings through which progressive flooding may take place and such flooding is not accounted for in the calculation of factor si. Such openings shall include air-pipes, ventilators and openings which are closed by means of weathertight doors or hatch covers; and

Regulation 7-2.5.2.1 Unprotected openings 1. The flooding angle will be limited by immersion of such an opening. It is not necessary to define a criterion for non-immersion of unprotected openings at equilibrium, because if it is immersed, the range of positive GZ limited to flooding angle will be zero so “s” will be equal to zero. 2. An unprotected opening connects two rooms or one room and the outside. An unprotected opening will not be taken into account if the two connected rooms are flooded or none of these rooms are flooded. If the opening is connected to the outside, it will not be taken into account if the connected compartment is flooded. An unprotected opening does not need to be taken into account if it connects a flooded room or the outside to an undamaged room, if this room will be considered as flooded in a subsequent stage. Openings fitted with a weathertight mean of closing (“weathertight openings”) 3. The survival “s” factor will be “0” if any such point is submerged at a stage which is considered as “final”. Such points may be submerged during a stage or phase which is considered as “intermediate”, or within the range beyond equilibrium. 4. If an opening fitted with a weathertight means of closure is submerged at equilibrium during a stage considered as intermediate, it should be demonstrated that this weathertight means of closure can sustain the corresponding head of water and that the leakage rate is negligible.

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5. These points are also defined as connecting two rooms or one room and the outside, and the same principle as for unprotected openings is applied to take them into account or not. If several stages have to be considered as “final”, a “weathertight opening” does not need to be taken into account if it connects a flooded room or the outside to an undamaged room if this room will be considered as flooded in a successive “final” stage. .2

any part of the bulkhead deck in passenger ships considered a horizontal evacuation route for compliance with chapter II-2. [Q37D – see below]

[.3

for ro-ro passenger ships, when damaged above the bulkhead deck, any part of the bulkhead deck in way of the damage opening in which the residual freeboard is less than [x] metres.

This could also apply to conventional passenger ships with large, un-subdivided spaces near the equilibrium waterplane. Proposal to be discussed under ro-ro damage stability agenda item] [Q37D– see below]. Regulation 7-2.5.2.2 1. Partial immersion of the bulkhead deck may be accepted at final equilibrium. The new This [CLIA Q11 CG agreed to retain original text] provision is intended to ensure that evacuation along the bulkhead deck to the vertical escapes will not be impeded by water on that deck. A “horizontal evacuation route” in the context of this regulation means a route on the bulkhead deck connecting spaces located on and under this deck with the vertical escapes from the bulkhead deck required for compliance with SOLAS chapter II-2. Regulation 7-2.5.2.2 EN 1 CLIA Q11: Comments received from CLIA/CCSF between round 1 and 2: Some small improvements have been made to clarify the definition of horizontal evacuation routes. 1. Partial immersion of the bulkhead deck may be accepted at final equilibrium. The [new] provision is intended to ensure that evacuation along the bulkhead deck to the vertical escapes will not be impeded by water on that deck. A “horizontal evacuation route” in the context of this regulation means a route on the bulkhead deck connecting spaces located on and under this deck with the vertical escapes from the bulkhead deck required for compliance with SOLAS chapter II-2. Coordinator’s Comments: CG Member’s Comments?:MI: Concur. Germany: Yes. China: 1. China has no objection to the word “[new]” inserted before “provision”. 2. However, for ro-ro passenger ships, the requirement that the evacuation route on bulkhead deck cannot be immersed is a big problem. Only crew evacuate from the machinery spaces below along the ro-ro deck (bulkhead deck) and passengers are not allowed to access into the ro-ro space at sea. Therefore the above text is suggested to be amended as follows: “1. Partial immersion of the bulkhead deck may be accepted at final equilibrium.

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The [new] provision is intended to ensure that evacuation along the bulkhead deck to the vertical escapes will not be impeded by water on that deck. A “horizontal evacuation route” in the context of this regulation means a route intended for the evacuation of passengers on the bulkhead deck connecting spaces located on and under this deck with the vertical escapes from the bulkhead deck required for compliance with SOLAS chapter II-2. ” Finland: Support. Italy: Agreed. France: OK US: It doesn’t seem the text in question (The new provision is...) is the actual text from reg 72.5.2.2 EN1. The actual text in MSC.281(85) reads: This provision is...; so we think ok as is. Round 2 Discussion:- Thank you US – a typing error when transposing MSC.281(85) must have crept in. Apologies. So we go back to the original text “This provision …etc.”. Meantime China has come up with a good point which illustrates the difference between conventional passenger ships and ro-pax ships. The problem for ro-pax ships is that partial immersion of the bulkhead deck in way of the damage opening at final equilibrium usually leads to the capsize of the ship (s=0) due to the WOD effect. So we suggest that China’s proposed amendment should only apply to the EN for regulation. 7-2.5.2.2 and we should consider introducing a new regulation specifically for ro-pax ships to account for the WOD effect:5.2 .3

for ro-ro passenger ships, when damaged above the bulkhead deck, any part of the bulkhead deck in way of the damage opening in which the residual freeboard is less than [x] metres.

This could also apply to conventional passenger ships with large, un-subdivided spaces near the equilibrium waterplane. CLIA Q11 (for SLF53 WG). Can we (a) agree that the original text is satisfactory and (b) that a new regulation may be needed for ro-ro passenger ships to ensure that si is zero if the residual freeboard in way of the damage opening when the roro vehicle space is damaged is less than [x] metres? (a) Yes/No? (b) Yes/No? Further Comments / Alternative proposals?:Post SLF 53 Notes:1. The WG agreed that the original text of EN 1 for Reg. 7-2.5.2.2 should remain unchanged (see above). 2. Proposed new Regulation 7-2.5.2.3 relating to residual freeboard and the “s” factor for ships with large, un-subdivided spaces near the equilibrium waterplane (see Round 2 Discussion) was put in the ToR for the 2011 SDS correspondence group (see SLF 53/9 paragraph 14.10.3) and will be dealt with by the Ro-Ro branch of the SDS CG (see SLF 54/8/1 paragraph 14.3).

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AT SLF54 1) NFA on Reg. 7-2.5.2.2. 2) Discuss under Ro-Ro damage stability (Agenda Item 6) in the context of other ongoing research projects. 2. Horizontal evacuation routes on the bulkhead deck include only escape routes (designated as category 2 stairway spaces according to SOLAS regulation II-2/9.2.2.3 or as category 4 stairway spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) used for the evacuation of undamaged spaces. Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) or escape routes within the damaged space. Landing areas and half landings of a staircase are part of the vertical escape way and not part of a horizontal escape route. [Q37D] [Coordinator’s Note: the CG in round 4 expressed some dissatisfaction with these EN changes which were agreed at SLF 53. Now we are awaiting responses to various options in the Round 6 questionnaire which may also involve changing the wording of the regulation itself. Discuss at SLF 54] No part of a horizontal evacuation route serving undamaged spaces should be immersed. Regulation 7-2.5.2 and 7-2.5.3 (ref. SLF 51/3/2 Annex – US and Sweden) The fact that part of escape routes or control systems of watertight doors or valves may be within the damage extent is not taken into account. It is specified in the explanatory notes that “Horizontal evacuation routes do not include corridors within the damaged spaces.” Is this acceptable if the corridor within the damaged space is used for evacuation from another undamaged space? R7-2.5.2.2 (Clarification of “horizontal evacuation routes”) . Q37. Do you agree that a change to the EN is needed? Yes

China, Spain, Denmark, UK, Sweden

No

Finland, Germany, Japan, MI, Norway, Italy, US

Comments / Proposals?:Norway: The current wording is a result of extensive discussions during previous sessions. A revisit should not be given priority at the moment. CLIA: see CSSF paper. Denmark: This EN will benefit from redrafting to improve clarity. US: Note: This SLF 51/3/2 item was made before the Explanatory Notes were finalized at SLF 51 and the space categories were added. Therefore this item does not account for the final discussions/decisions made at SLF 51. Round 1 Discussion: Based on the comments received, it would seem that there is a slight majority (7/5) in favour of keeping the EN as they stand. However, if there are ways in which the text can easily be improved and clarified, as hinted at by Denmark, may we invite specific proposals? Q37A. In the light of the comments received in Round 1, should we keep the EN relating to horizontal evacuation routes as they are? Please note the proposals by CLIA/CSSF below.

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Yes

MI, Germany, Finland, Japan, RINA, Norway, US (with comment), Sweden, Denmark

No

France (with comments), CLIA (see proposals), UK (with comment)

If “No” do you have specific proposals for improving the text?:China:- For ro-ro passenger ships, the requirement that the evacuation route on bulkhead deck cannot be immersed is a big problem. Only crew evacuate from the machinery spaces below along the ro-ro deck (bulkhead deck) and passengers are not allowed to access into the ro-ro space at sea. Therefore the above text is suggested to be amended as follows: “1. Partial immersion of the bulkhead deck may be accepted at final equilibrium. The [new] provision is intended to ensure that evacuation along the bulkhead deck to the vertical escapes will not be impeded by water on that deck. A “horizontal evacuation route” in the context of this regulation means a route intended for the evacuation of passengers on the bulkhead deck connecting spaces located on and under this deck with the vertical escapes from the bulkhead deck required for compliance with SOLAS chapter II-2. ” Italy: CLIA comment is agreed. RINA: Sketches describing the acceptable and non-acceptable arrangements would assist the understanding of the requirements. France: It seems that the intent is to exclude corridors designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers. To clarify this it may be sufficient just to delete “within the damaged spaces”. (Anyway, situation outside flooded spaces is not considered). This could be considered as not acceptable if escape route from an undamaged space go through such corridors and if there is no alternative way. So, alternative interpretation may be to consider that such corridors may be excluded only if they are used for evacuation of the space where they are (above the bulkhead deck). If evacuation route from undamaged spaces below the bulkhead deck go through such corridors, they should not be excluded. Alternative wording may be : “Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) within the damaged space, except if they are used for escape from undamaged spaces below the bulkhead deck.” CLIA: CLIA - See CLIA/SSF proposals. UK: CLIA/CSSF proposed modifications can be implemented. US: Accept as noted in response to second CLIA proposal below. Round 2 discussion of EN 2 follows CLIA’s additional comments, below. Additional comments received from CLIA/CCSF between round 1 and 2: Regulation 7-2.5.2.2 EN 2 2. Horizontal evacuation routes on the bulkhead deck include only escape routes (designated as category 2 stairway spaces according to SOLAS regulation II-2/9.2.2.3 or as category 4 stairway spaces according to SOLAS regulation II-2/9.2.2.4 for passenger

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ships carrying not more than 36 passengers) used for the evacuation of undamaged spaces. Horizontal evacuation [routes] do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) [or escape routes] within the damaged space. [Landing areas and half landings of a staircase are part of the vertical escape way and not part of a horizontal escape route.] No part of a horizontal evacuation route serving undamaged spaces should be immersed. Coordinator’s Comments: “Routes” and “escape routes” is made bold for emphasis. Please consider these modifications in your reply to Q37A, above. CG Member’s Comments?:Germany: CSSF proposals help to clarify. Finland: Proposal will help to clarify more precisely. France: It should be necessary to define what a vertical escape route is. US: We do not agree to the proposed additions. Round 2 Discussion:- There is good support for CLIA’s proposed amendments but the US is opposed. China’s comments regarding ro-ro passenger ships are noted and have been discussed under EN 1, above. RINA’s request for explanatory sketches is also noted (we are not sure whether the sketch provided for EN 4, below would be enough?). France would like a definition of “vertical escape route” and also has two alternative proposals:(1) 2. Horizontal evacuation routes on the bulkhead deck include only escape routes (designated as category 2 stairway spaces according to SOLAS regulation II-2/9.2.2.3 or as category 4 stairway spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) used for the evacuation of undamaged spaces. Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) [within the damaged space]. No part of a horizontal evacuation route serving undamaged spaces should be immersed. (2) 2. Horizontal evacuation routes on the bulkhead deck include only escape routes (designated as category 2 stairway spaces according to SOLAS regulation II-2/9.2.2.3 or as category 4 stairway spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) used for the evacuation of undamaged spaces. Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) within the damaged space, [except if they are used for escape from undamaged spaces below the bulkhead deck]. No part of a horizontal evacuation route serving undamaged spaces should be immersed. It would seem that this question will need to be discussed further by the SFL 53 WG when the views of the other members can also be obtained. Q37B (for the SLF 53 WG). In the light of the comments now received in Round 2, do you prefer to keep the EN relating to horizontal evacuation routes unchanged or do you prefer the amendments proposed by CLIA or France (1 or 2)?

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No change? CLIA? France (1)? France (2)? Further comments / alternatives?:Post SLF 53 Note:- The WG, after considerable discussion, agreed to amend EN2 as shown above. Q37C Any final comments (for Round 4 questionnaire)?:Comments?:US: We are not satisfied with this result and strongly prefer the original version of EN 2. A particular concern is the combination of adding “or escape routes” with the deletion of “within the damaged space” in the second sentence. This combination of different proposals cannot be correct because it would seem to exempt all escape routes and therefore contradict the first sentence. However, as a general comment we think it is important to keep in mind that the intent of regulation 7-2.5.2.2 is to cover the significant “non-stability” benefits of a margin line. With a margin line it didn’t matter whether the bulkhead deck escape routes/ corridors/stair landings were within the damage extent or not because the bulkhead (or where it used to be) had to remain dry. Norway: Having considered this matter in depth, Norway is very concerned about totally ignoring corridors from the term – horizontal evacuation routes. On larger vessels, a serious physical obstruction may occur in corridors (3 m head of water on 42 m beam vessel). Norway therefore proposes to keep the original EN (MSC 85/26/Add. 1 Annex 22, page 25) text. With regards to proposal of specifying landings and half-landings as “not part of a horizontal escape route” we cannot see the need for this. The start of a staircase at the bulkhead deck level will be defined as a flooding point, and any landing or half-landing will be above this level, and are thus governed by the flooding point at the bulkhead deck level. China: No comments. RINA: It is not clear as to why “or escape routes” at the beginning of the new text has been added? Denmark: Unable to understand the sentence ending with “or escape routes”; we still need to retain the words “within the damaged space”. Germany: No comments. Italy: The deleted part “within the damaged space” should be maintained. With ref. to the attached figures, supposing that the spaces are damaged below and also above the bhd. deck, with transversal extension of the damage up to B/2, the horizontal evacuation route would not be available (destroyed) – therefore a verification is not needed. AMENDMENT TO EN2 BY THE WG IS AGREED, AS SHOWN ABOVE. France: In the second sentence, is it correct to exclude “escape route”? What is the meaning of escape route in this sentence? It should be necessary to define what are a “landing area” and “half landing of a stair case”. Round 6 Discussion: Strictly speaking, this item was finalised by the SLF 53 WG but although it was discussed in detail there were a variety of options on the table and the outcome was, as we recall, decided by majority rather than unanimously. It is possible

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that the alterations in grey and the strikeout (taken from SLF.53/WP.6 Annex 5, page 79) do not correctly reflect what was finally agreed which is why we asked for comments in Q37C. The US points out that the agreed text as highlighted in grey above is not self-consistent. It would make more sense if the words “within the damaged spaces” were retained (Denmark, France, RINA and Italy agree). Norway has problems with totally ignoring corridors and also with including stairways in escape routes; Norway and the US prefer the original EN. The US points out that the underlying purpose of reg. 7-2.5.2.2 is to mitigate the loss of the concept of non-immersion of the old margin line in S90. The co-ordinators have always had some difficulties in understanding this regulation and accompanying EN so we thought we would break the latter into simpler sections to understand the implications more clearly (and to try to explain it better to ourselves!). To start with here is the relevant part of the original regulation for easy reference:5.2 In all cases, si is to be taken as zero in those cases where the final waterline, taking into account sinkage, heel and trim, immerses: .2 any part of the bulkhead deck in passenger ships considered a horizontal evacuation route for compliance with chapter II-2. Simplifying the original EN by cutting out the bracketed designations for “escape routes” and “corridors” it states:2. (a) Horizontal evacuation routes on the bulkhead deck include only escape routes used for the evacuation of undamaged spaces. (b)

Horizontal evacuation routes do not include corridors within the damaged space.

(c) No part of a horizontal evacuation route serving undamaged spaces should be immersed. Implication (a) is that a designated horizontal evacuation route on the bulkhead deck used as an escape route from a damaged space does not count as a horizontal evacuation route for the purpose of reg. 5.2.2; therefore in such damage cases si may be non-zero and contribute to A. Implication (b) is that corridors initially considered to form part of a horizontal evacuation route on the bulkhead deck but lying within a damaged space on the bulkhead deck in fact no longer count as horizontal evacuation routes for the purpose of reg 5.2.2; therefore in such damage cases si may be non-zero and contribute to A. This also implies that corridors on the bulkhead deck initially considered to form part of horizontal evacuation routes serving an undamaged space (on the bulkhead deck? anywhere?) and not themselves lying within a damaged space on the bulkhead deck may always be considered to be horizontal evacuation routes but if they become immersed si is to be taken as zero. This would be consistent with (c). Implication (c) is that if any part of the bulkhead deck containing a horizontal evacuation route serving an undamaged space becomes immersed si is to be taken as zero.

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The first text change agreed at SLF 53 was for (b) to read:(b)

Horizontal evacuation routes do not include corridors or escape routes.

This implies that corridors or escape routes are not considered to be horizontal evacuation routes; therefore in all damage cases involving corridors or escape routes si may be non-zero and contribute to A. This seems clearly wrong! If we leave in the struck out words “within the damaged spaces” we get:(b) Horizontal evacuation routes do not include corridors or escape routes within the damaged spaces. The implications here are similar to implication (b) above except that “corridors” is replaced with “corridors or escape routes”. The second text change agreed at SLF 53 was to introduce a new sentence:Landing areas and half landings of a staircase are part of the vertical escape way and not part of a horizontal escape route. This implies in effect that staircases are not considered to be part of the horizontal escape route; therefore in all damage cases involving staircases si may be non-zero and contribute to A. As Norway points out, however, it is hard to see the need for this. Co-ordinator’s Comments: 1) We think that the original intent of reg. 7-2.5.2.2 is simply, as the US pointed out, to replace the concept of margin line non-immersion. We now allow partial flooding of the bulkhead deck up to the waterline at which the designated passenger escape routes (or the openings defined in reg. 7-2.5.2.1 or the stairways mentioned in EN 3) become immersed. If the minimum of two such designated routes required by SOLAS CH II-2 Part D Reg. 13.2 are placed as near to the centreline as is reasonably allowed by the term “widely separated” or indeed are not placed on the bulkhead deck at all then, in theory, considerable (or total?) flooding of the bulkhead deck on passenger ships is now permissible. 2) The resulting complexity of the EN is obvious. Of course, simplification could be achieved by shortening reg. 7-2.5.2.2 to read:5.2 In all cases, si is to be taken as zero in those cases where the final waterline, taking into account sinkage, heel and trim, immerses: .2 any part of the bulkhead deck in passenger ships [considered a horizontal evacuation route for compliance with chapter II-2]. This is clearly no longer possible as we would effectively have re-introduced the margin line! 3) We do not really understand why reg. 7-2.5.2.2 refers to complex fire regulations in chapter II-2, especially those involving stairway and corridor spaces (in the

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EN). For stability purposes we are surely not interested in fire-proofed stairways or corridors but only in how far the damage waterline extends over the bulkhead deck and whether the designated escape routes are immersed. Incidentally, in the event of there being several escape routes must all of them be immersed for s=0 or only one? 4) We could therefore simply define the two (or all) approved escape routes required by Ch II-2 Part D Reg. 13.2 (but only where they involve evacuation along the bulkhead deck) in terms of (x,y,z) co-ordinates (similar to unprotected openings). Only the “outboard” co-ordinates would be needed for input to the probabilistic damage calculations. 5) Any damage case resulting in immersion of any part of any of the defined escape routes would be assigned s=0. The issue of whether all escape routes lie within the extent of a given damage scenario should not arise. We should only be penetrating to B/2 so there ought always to be an alternative escape route on the other side of the bulkhead deck. The software could be programmed to discount all escape route co-ordinates lying within the extent of damage of a particular case (just as for other openings) but if floodwater extends across the bulkhead deck past B/2 submerging the “non-discounted” co-ordinates then the case would be assigned as s=0. The co-ordinator’s experience of the complexity of passenger ship evacuation regulations and procedures is, however, very limited so we apologise if the above makes no sense! If a procedure like this does make sense, however, and is acceptable to the group we could amend the regulation by specifically quoting SOLAS CH II-2 Part D Reg. 13.2 and by simplifying EN 2, 3 and 4 considerably. EN 4 is discussed in CLIA Q12C, below. Q37D (for Round 6 questionnaire). Considering all the above points would you a) Consider clarifying reg. 7-2.5.2.2 by referring to Ch II-2 part D Reg. 13.2 and simplifying the EN by using the procedure outlined in the co-ordinator’s comments? OR b) prefer to leave the regulation alone but modify part of the EN to read:Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) or escape routes within the damaged space. Landing areas and half landings of a staircase are part of the vertical escape way and not part of a horizontal escape route. ? OR c) prefer to keep everything as agreed at SLF 53 (ref. SLF.53/WP.6, Annex 5)? d) prefer to revert to the original reg. and EN? Prefer a) Y/N?

Yes: RINA, Denmark, China No: Finland, Norway, Germany, France Comment: US (Although we are not necessarily opposed to this general approach, it would represent a significant departure from that negotiated in the current EN approach (as it is much closer to a complete escape route margin line)

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Prefer b) Y/N?

Yes: CLIA, Norway, UK No: Finland, Germany, US (but much better than option c), France, Denmark

Prefer c) Y/N?

Yes: Finland, Germany, France (but see comment) No: Norway, US, Denmark

Prefer d) Y/N?

Yes: Norway (but see comment), US No: Finland, Germany, France, Denmark

Further comments / alternatives?:Norway to d): prefer the amendments shown under b). Italy: “Horizontal evacuation routes do not include corridors (designated as category 3 corridor spaces according to SOLAS regulation II-2/9.2.2.3 or as category 2 corridor spaces according to SOLAS regulation II-2/9.2.2.4 for passenger ships carrying not more than 36 passengers) or escape routes within the damaged space. Landing areas and half landings of a staircase are part of the vertical escape way and not part of a horizontal escape route.” (i.e. text without deleting any part of the sentence and, in particular, maintaining “within the damaged spaces”) France: In wording agreed at SLF53, France would delete [or escape routes] in the second sentence and the third sentence in square bracket (otherwise, landing area and half landing area of a staircase should be defined.) Q37 There is no general preference for options a) through d), therefore we can only refer the various issues and proposals to SLF 54 for further discussion, also bearing in mind the link to CLIA Q12. DISCUSS FURTHER AT SLF 54 3. si = 0 where it is not possible to access a stair leading up to the embarkation deck from an undamaged space as a result of flooding to the “stairway” or “horizontal stairway” on the bulkhead deck. 4. Horizontal escapes situated in way of the damage extent may remain effective, therefore si need not be taken as zero. Contributions to the attained index A may still be gained. [CLIA Q12] [Coordinator’s Note: At SLF 53 it was agreed to replace the text of EN4 with a new diagram and introductory text, below. However some members did not accept this and so the entire question of EN’s 2,3 and 4 has been transferred to Q37.]:R 7-2.5.2.2 EN 4 CLIA Q12: Additional comments received from CLIA/CCSF between round 1 and 2: Regulation 7-2.5.2.2 EN 4 4. Horizontal [and vertical] escapes situated in way of the damage extent may remain effective, therefore si need not be taken as zero. Contributions to the attained index A may still be gained.

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[Example for horizontal escape routes:] "horizontal escape way" to be kept dry

Evacuation route from undamaged space

damaged compartments

Coordinator’s Comments: Please consider these proposed modifications in your reply to Q37A, above. CG Member’s Comments?:Germany: CSSF proposals help to clarify. Finland: Proposal will help to clarify more precisely. Italy: CLIA comments are agreed. US: We can accept this proposed change (i.e. the addition of [and vertical]). Note: for the example shown we understand this to be an s=0 case; if example is included this should be indicated. We propose that “if not immersed” be added after “remain effective” to clarify this point. Round 2 Discussion:- Three members support CLIA’s proposal and the US can accept provided the example is identified as an “s=0” situation and some clarification is added:4. Horizontal [and vertical] escapes situated in way of the damage extent may remain effective [if not immersed], therefore si need not be taken as zero. Contributions to the attained index A may still be gained. It seems that this should be put to the SLF WG for a final decision and to allow more members to contribute.

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CLIA Q12 (for SLF53 WG). Can you accept CLIA’s proposal as it stands (including the diagram) or do you prefer to include the US’ amendments? CLIA only? CLIA + US? Further comments / alternatives?:Post SLF 53 Note:- The WG decided to delete the EN altogether (believing it could be confusing) but to include an updated version of the sketch to try to show more clearly the difference between damaged and flooded compartments. Germany agreed to improve CLIA’s sketch and forward it to the CG for consideration and inclusion in the EN. CLIA Q12C (for Round 4 Questionnaire):- Is Germany able to improve the above drawing as agreed at the SFL 53 WG to better reflect the difference between “flooded” and “damaged” compartments/spaces? Space for Revised Drawing / Further Comments?:US: In line with our comments in Q37C above, we are generally not in favour of deleting EN 4. It may need some clarification/revision but we see this EN as trying to replicate the margin line concept that during stability calculations we ignore potential damage to the bulkhead deck. China: No comments. Denmark: No comments. Germany: (Has provided a new diagram – see below. Many thanks. However it is rather blurred – can the quality be improved a little?)

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Round 6 Discussion: The US would prefer to retain the EN for the reasons stated. We suggest that the future of EN’s 2, 3 and 4 will now depend on what is decided in response to Q37D, above. So we propose in future to link any action on CLIA Q12C to Q37D. Further Comments / alternatives?:Coordinator’s Note: New diagram provided by Germany in round 6 response (below). MANY THANKS!

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Denmark: No further comments. China: No (comments). CLIA Q12 Some CG members are not in favour of deleting the original text so the whole question of the EN’s for reg. 7-2.5.2.2 is to be re-examined under Q37D. DISCUSS AT SLF 54

5.3 The factor si is to be taken as zero if, taking into account sinkage, heel and trim, any of the following occur in any intermediate stage or in the final stage of flooding: .1

immersion of any vertical escape hatch in the bulkhead deck intended for compliance with chapter II-2;

Regulation 7-2.5.3.1 1.

The purpose of this paragraph is to provide an incentive to ensure that

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evacuation through a vertical escape will not be obstructed by water from above. The paragraph is intended for smaller emergency escapes, typically hatches, where fitting of a watertight or weathertight means of closure would otherwise exclude them from being considered as flooding points. 2. Since the probabilistic regulations do not require that the watertight bulkheads be carried continuously up to the bulkhead deck, care should be taken to ensure that evacuation from intact spaces through flooded spaces below the bulkhead deck will remain possible, for instance by means of a watertight trunk.

.2

any controls intended for the operation of watertight doors, equalization devices, valves on piping or on ventilation ducts intended to maintain the integrity of watertight bulkheads from above the bulkhead deck become inaccessible or inoperable;

.3

immersion of any part of piping or ventilation ducts carried through a watertight boundary that is located within any compartment included in damage cases contributing to the attained index A, if not fitted with watertight means of closure at each boundary.

.3

immersion of any part of piping or ventilation ducts [that is] located within the assumed extent of damage and carried through a watertight boundary if this can lead to the progressive flooding of compartments not assumed as flooded. Coordinator’s Note:- See below for reason for square brackets in amended text.

R7-2.5.3.3 (Clarification of “boundary”) CLIA Q13 Comments received from CLIA/CCSF between Round 1 and Round 2: Regulation 7-2.5.3 Watertight closure of open pipes: The wording “boundary” in para 3 could be interpreted as “boundary of the compartment”. It is our understanding that this is not the intention of the regulation.

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Therefore following change is proposed:.3 immersion of any part of piping or ventilation ducts carried through a watertight boundary that is located within any compartment included in damage cases contributing to the attained index A, if not fitted with watertight means of closure at each boundary. Coordinator’s Comments: Can we agree to this modification to Reg. 7-2.5.3.3? CG Member’s Comments?:MI: Concur. Germany: CSSF proposals help to clarify. Finland: Proposal will help to clarify more precisely. Italy: Agreed. France: The objective is to prevent progressive flooding of other compartment through pipes or ventilation ducts which may be broken by damage extent. Alternatively, progressive flooding may be taken into account in calculations. Other proposal may be .”3 immersion of any part of piping or ventilation ducts that is located within the assumed extent of damage and carried through a watertight boundary if this can lead to the progressive flooding of compartments not assumed as flooded.” UK: prefer to add “watertight” to enhance the addressing rather then removing it. [Coordinator – does UK mean to say “at each watertight boundary” at end of sentence – please clarify]. US: Not sure completely understand the concern; therefore abstain from comments. Round 2 Discussion:- There is good support for CLIA’s proposed amendment to the regulation amongst those who commented but the US and UK have reservations and France has an alternative proposal. We therefore suggest that this be discussed at the SLF 53 WG to allow others to contribute. CLIA Q13 (for SLF53 WG). Do you prefer “no changes” to the regulation or CLIA’s proposal or France’s alternative version? No change? CLIA? France? Further comments / alternatives?:Post SLF 53 Note:- The WG preferred France’s revision of Reg. 7-2.5.3.3:.3 immersion of any part of piping or ventilation ducts that is located within the assumed extent of damage and carried through a watertight boundary if this can lead to the progressive flooding of compartments not assumed as flooded. We have re-read this text and would like to propose a very minor change, if still possible, for language reasons:.3 immersion of any part of piping or ventilation ducts that is located within the assumed extent of damage and carried through a watertight boundary if this can lead to the progressive flooding of compartments not assumed as flooded. CLIA Q13C (for Round 4 Questionnaire). Although the revised text for Reg. 72.3.3.3 was agreed by the SLF 53 WG the coordinators propose to remove the words “that is” as shown within square brackets (for language reasons only). Are you happy with this minor edit (assuming we are still permitted to change it)?

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Yes No

Vanuatu, US, Sweden, Norway, Japan, RINA, Denmark, France, Germany, Finland, Italy, EC, UK, CLIA, ICS, MI (agree proposed editorial change), Spain China

Final Comments?:Denmark: Progressive flooding can be accepted according to EN Reg. 7-2, para. 3 provided that the calculation of the damage with and without progressive flooding is carried out and the damage giving the smaller s included in the index calculation. Round 6 Discussion. A large majority are in favour of this minor editorial change so we will report it to the sub-committee accordingly. We hope that the honourable delegation from China can accept the views of the majority? Denmark’s comments on reg 7-2 EN 3 are duly noted.

CLIA Q13 CONCLUDED; R7-2.5.3.3 TEXT CHANGED TO READ . 3 immersion of any part of piping or ventilation ducts that is located within the assumed extent of damage and carried through a watertight boundary if this can lead to the progressive flooding of compartments not assumed as flooded. WE RECOMMEND THIS MODIFICATION BE ACCEPTED AT SLF 54 5.4 However, where compartments assumed flooded due to progressive flooding are taken into account in the damage stability calculations multiple values of sintermediate,i may be calculated assuming equalization in additional flooding phases. 5.5 Except as provided in paragraph 5.3.1, openings closed by means of watertight manhole covers and flush scuttles, small watertight hatch covers, remotely operated sliding watertight doors, side scuttles of the non-opening type as well as watertight access doors and hatch covers required to be kept closed at sea need not be considered. 6 Where horizontal watertight boundaries are fitted above the waterline under consideration the s-value calculated for the lower compartment or group of compartments shall be obtained by multiplying the value as determined in paragraph 1.1 by the reduction factor vm according to paragraph 6.1, which represents the probability that the spaces above the horizontal subdivision will not be flooded. Regulation 7-2.6 The sketches in the figure illustrate the connection between position of watertight decks in the reserve buoyancy area and the use of factor v for damages below these decks.

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Regulation 7-2.6.1 The parameters x1 and x2 are the same as parameters x1 and x2 used in regulation 7-1. [New Co-ordinator’s Note for Round 2: It is proposed that we delete this EN and change the subscripts in this Reg. to match those in Reg 7-1 as this would involve the least number of changes. Comments invited: US: Unsure; recommend following whatever “standard convention” for subscript formatting is. Question: x1 and x1 are defined differently; is that an issue? Co-ordinator’s comment: Many thanks, US. For simplicity, we could just leave the EN as it stands. POST SLF 53 Note:- No further action needed] [NFA at SLF 54]

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Regulation 7-3 Permeability 1 For the purpose of the subdivision and damage stability calculations of the regulations, the permeability of each general compartment or part of a compartment shall be as follows: Spaces Permeability Appropriated to stores 0.60 Occupied by accommodation 0.95 Occupied by machinery 0.85 Void spaces 0.95 Intended for liquids 0 or 0.95* *

Whichever results in the more severe requirement.

2 For the purpose of the subdivision and damage stability calculations of the regulations, the permeability of each cargo compartment or part of a compartment shall be as follows: Spaces Dry cargo spaces Container spaces Ro-ro spaces Cargo liquids Regulation 7-3.2 1.

Permeability at draught ds

Permeability at draught dp

Permeability at draught dl

0.70 0.70 0.90 0.70

0.80 0.80 0.90 0.80

0.95 0.95 0.95 0.95

The following additional cargo permeabilities may be used: Spaces

Timber cargo in holds Wood chip cargo

Permeability at draught ds

Permeability at draught dp

Permeability at draught dl

0.35 0.60

0.70 0.70

0.95 0.95

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2. Reference is made to MSC/Circ.998 (IACS Unified Interpretation regarding timber deck cargo in the context of damage stability requirements) regarding timber deck cargo. [Coordinator’s Note: included below for easy reference].

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3

Other figures for permeability may be used if substantiated by calculations. Regulation 7-3.3 1. Concerning the use of other figures for permeability “if substantiated by calculations”, such permeabilities should reflect the general conditions of the ship throughout its service life rather than specific loading conditions. 2. This paragraph allows for the recalculation of permeabilities. This should only be considered in cases where it is evident that there is a major discrepancy between the values shown in the regulation and the real values. It is not designed for improving the attained value of a deficient ship of regular type by the modification of chosen spaces in the ship that are known to provide significantly onerous results. All proposals should be considered on a case-by-case basis by the Administration and should be justified with adequate calculations and arguments.

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Regulation 8 Special requirements concerning passenger ship stability EITHER (US Proposal to delete reg. 8.1):[1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for the three loading conditions on which is based the calculation of the subdivision index and for a damage involving all the compartments within 0.08L measured from the forward perpendicular.] OR:[1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index.] Regulation 8.1 The intention of this regulation is to prevent the fitting of a large compartment aft of the collision bulkhead. [Q39-41D] Regulation 8.1 (ref. SLF 52/17/6 - Norway) Paragraph 1 is inconsistent with paragraph 3, 3.2 and 3.4 in the same regulation. In this case it is proposed that the damage length should be relative to L in order to coincide with the damage length implied in regulation 12.1 on location of the collision bulkhead. Ls should then be replaced with L in the following paragraphs: Regulation 8.3 Regulation 8.3.2 Regulation 8.3.4 [Coordinator’s Note – indicated in square brackets below.] R8.1 (Inconsistent use of Ls) . Q38. Do you agree that the changes proposed by Norway are needed for consistency? Yes No

China, Germany, Japan, MI, Norway, CLIA, Italy, Spain, Denmark, UK, US, Sweden Finland

Comments / Alternatives?:Round 1 Discussion: A large majority is in favour (12/1). Can Finland accept the majority’s view? IT IS PROPOSED TO ACCEPT THESE AMENDMENTS SUBJECT TO ANY FINAL COMMENTS FROM FINLAND Comments?:Finland: Can accept.

CONCLUDED - PROPOSAL ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53.

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(See SLF 53/14 para 12.6). POST SLF 53 Note:- The changes were accepted in plenary at SLF 53; they are shown highlighted in red below. AT SLF 54 RECOMMEND ACCEPTANCE OF NORWAY’S PROPOSALS --------------------It has been concluded at several sessions that the revised SOLAS chapter II-1 must contain a requirement for full survivability (s = 1) in cases of damages forward of the collision bulkhead. This Administration shares this concern and proposes that appropriate amendments be included in regulation 12 as shown below [see Reg 12.1 for details]. Depending on the outcome of that discussion paragraph 8.1 may then become redundant. Otherwise paragraph 8.1 should be amended as follows [underlined]: “1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 in all service conditions used for calculation of a subdivision index assuming a damage involving all the compartments within 0.08L measured from the forward perpendicular.” R8.1 (and proposed new R12.2) covering fore end damages R8.1 (possible new EN) . Q39. Bearing in mind that Regulation 8 refers specifically to passenger ship stability only, and Reg 8.1 currently only applies to passenger ships carrying 400 or more persons, do you agree that s should be equal to 1 for cases of damage involving all the compartments within 0.08L measured from the FP for this specified class of ship only, as in current Reg. 8.1? The question of s = 1 in other forward damage cases, as raised by Japan in SLF 51/3/2, would then be covered by Regulation 12 (please also refer to Reg. 12). Yes Finland, Germany with comments (Q41 is preferred), Japan, Norway, CLIA, Italy, Spain, Denmark, Sweden No China, US Comments?:China: The proposed replacement of “3 loading conditions” with “all service conditions” implies that the damage stability of all real loading conditions in the loading manual should calculated, which leads to a huge volume of calculation in comparison with “3 loading conditions”. Finland: s=1 to be applied for all ships under SOLAS2009. Germany: Requirement s=1 shall be applicable for all vessels covered by SOLAS2009. Norway: If there is general agreement that regulation 12 should make this a universal requirement for all ships we can withdraw this proposal. UK: See Q41. US: With the proposed addition to regulation 12, regulation 8.1 should be deleted. Note: this also would solve what seems to be awkward text in regulation 8.1; it indicates “watertight subdivision abaft the collision bulkhead so that s=1” but it is addressing damage forward of the collision bulkhead. Please see Q41 for discussion.

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. Q40. If you answered “yes” to Q39 do you then agree with Norway’s clarifying amendment to Reg. 8.1, underlined in bold above? Yes Finland, Germany with comments (Q41 is preferred), Japan, Norway, CLIA, Spain, Denmark, Sweden No Italy Comments?:China: See comments to Q39. Germany: Requirement s=1 shall be applicable for all vessels covered by SOLAS2009 Norway: If there is general agreement that regulation 12 should make this a universal requirement for all ships we can withdraw this proposal. Italy: Text to be modified as follows : “…watertight subdivision abaft the collision bulkhead so that si = 1 for the loading conditions on which is based the calculation of a subdivision index …” Denmark: The service conditions used for calculation of the index don’t cover the permissible trim range (which is probably what this wording is trying to achieve), but rather 0.5%L less (or whatever the interval is going to be revised to). Surely the maximum trim(s) would be the limiting condition(s) to be checked? As to whether the intervening conditions less than this need to be checked as well is less clear. UK: See Q41. US: N/A; delete regulation 8.1. Please see Q41 for discussion.

. Q41. Norway proposes as an alternative that Reg 8.1 could be deleted altogether and the general issue of s = 1 for forward damages, as raised by Japan in SLF 51/3/2, could be dealt with under Regulation 12 with a new paragraph 12.2:“2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 for all service conditions if [the whole portion] [any part] of the ship forward of the collision bulkhead is flooded without vertical limits.” Given that Regulation 12 applies to all vessels – passenger and cargo ships without any size limitations – do you agree with this proposal by Norway and their proposed wording of new Reg. 12.2? (The main implication seems to be that the s=1 requirement for forward damages would now apply to all sizes and classes of ship). Yes

Finland, Germany, Japan, Norway, Italy, Spain, UK, US, Sweden

No

China, Denmark

Comments?:China: The proposal by Japan of full damage fwd of collision bulkhead is taken from the old SOLAS Reg.25-6.2 which applies to cargo ships of over 80m in Ls. For passenger ships, Reg.8 of SOLAS 2009 is enough. Norway: We support this as an alternative to amending regulation 8. CLIA: Other ship types. Italy: Agreed in principle, but subject to further verification.

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Spain: We think that 8.1 and new 12.2 are not equivalent. We prefer to maintain both regulations. Denmark: We agree with the principle that all damages in all likely service conditions forward of the collision bulkhead should be survived, however we would like to see some studies showing the implications of this requirement on vessels which have never been required to comply, in order to minimise unintended consequences. At the same time, the new wording has the effect of relaxing the existing requirements for passenger ships since the 0.08L length would for some vessels mean the damaging of compartments aft of the collision bulkhead. Discussion on Q39-41 and Reg. 12.1: There seems to be strong but not total support for applying s=1 to forward damages in both cargo ships and passenger ships by deleting Reg 8.1 altogether and introducing a new Reg. 12.2 with the text as proposed above by Norway (square brackets to be resolved). For ease of reference, here are the proposals for dealing with Reg. 12:“Regulation 12 (ref. SLF 51/3/2 Annex – US and Sweden) New paragraph? Japan would again like to draw attention to the issue that the revised SOLAS chapter II-1 does not contain a requirement for full survivability (s = 1) in case of damages forward of the collision bulkhead; this should be identified for future improvement of the SOLAS text (see SLF 49/17, paragraph 3.5.3). Also see SLF 49/3, paragraph 10 below: “10 In addition, Japan provided further information to the group regarding the issue that the new revised SOLAS chapter II-1 does not contain a requirement for full survivability (s = 1) in case of damages in front of the collision bulkhead (see SLF 48/21, paragraph 3.35). This information was circulated to the group and comments were requested. From the group‘s comments, there were three general conclusions: (1) there was general agreement that s = 1 for damages forward of the collision bulkhead should be a basic SOLAS chapter II-1 requirement for all ships; (2) this chapter II-1 regulatory omission is generally not viewed as a serious weakness/problem; and (3) this problem cannot be addressed in the Explanatory Notes; it will require a SOLAS amendment (consistent with the SLF 48 view).” Note: This is already covered by damage of 0.08L from the forward perpendicular for passenger ships carrying more than 400 persons. Regulation 12 (ref. SLF 52/17/6 - Norway) As pointed out above [Coordinator’s note: see Regulation 8.1 and 8.2] the revised chapter does not contain a requirement for full survivability (s = 1) in case of damages forward of the collision bulkhead. This Administration proposes to amend the regulation by adding a new paragraph 2: “2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 for all service conditions if [the whole portion] [any part] of the ship forward of the collision bulkhead is flooded without vertical limits.” Below is a brief summary of the advantages and disadvantages of deleting Reg. 8.1 and introducing a new Reg. 12.2:Advantages. 1)

It introduces harmonisation of the regulations for cargo ships with L>=80 m

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and passenger ships of all sizes and passenger numbers, based on the principle that damage forward of the collision bulkhead shall not result in loss of the vessel in any service condition. 2) As pointed out by the US, it resolves issues surrounding the rather awkward wording of Reg 8.1, particularly if the unambiguous text “…..the whole portion of the ship forward of the collision bulkhead….” is adopted in proposed Reg. 12.2. 3) We no longer need to revise the wording of Reg. 8.1 as proposed by Norway (see Q39 and 40). 4) As Japan has pointed out (ref. SLF 51/3/2), omission of something equivalent to SOLAS90 Reg. 25-6.2 in S2009 during the harmonisation process may have been an oversight which can only be properly corrected now:-

This regulation is necessary because survival of damages forward of the collision bulkhead would have been achieved automatically under the previous deterministic system of floodable lengths and 1 or 2 compartment damages for passenger ships whereas under a probabilistic system, it would be permissible for a ship to meet overall safety standards, such as A>=R but not survive a fore end collision. 5)

It removes the 400 person and 0.08L thresholds in Reg. 8.1.

Disadvantages. 1) China is concerned that applying the standards in proposed Reg. 12.2 to all service conditions could result in a large volume of extra calculations. 2) It would introduce step changes in safety standards resulting in a class of “pre-removal of Reg. 8.1 and introduction of Reg 12.2” S2009 ships. For example, passenger ships carrying 399 persons or less would now be required to meet s=1 for fore end collisions as would new cargo ships. Denmark suggests there may be a relaxation for some passenger ships where the existing regulations require damages up to 0.08L to achieve s=1; in some cases this could mean investigating damages aft of the collision bulkhead whereas the new proposal would only require s=1 for damages forward of the collision bulkhead. As Denmark and Italy point out, verification of these changes would be needed to ensure that there are no further unintended consequences. 3) Paragraph re-numbering and consequent revision of cross-references would be needed in Regs. 8 and 12. Further Comments 1) Spain does not believe that Reg. 8.1 and proposed Reg. 12.2 are equivalent and would prefer to keep them both. 2) China would prefer to keep the passenger ship elements of the regulations as they are. 3) There is some concern over the draughts and trims to be assumed or whether actual service conditions should be used to demonstrate s=1 for damages forward of the collision bulkhead. For example, SOLAS90 Reg 25-6.2 only requires examination at the deepest subdivision load line

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(no mention of trim). S2009 Reg. 8.1 requires use of “the 3 loading conditions on which is based the calculation of the subdivision index……” (presumably this would be for ds and dp at level trim and dl at service trim, but there is no mention of further conditions if trim exceeds 0.5% of L, a point mentioned by Denmark in their response to Q40). The proposal for new Reg 12.2 by Norway suggests that “all service conditions” should be examined whereas in their original proposal for updating Reg. 8.1 they referred to examination in all service conditions used for calculation of a subdivision index. Italy in responding to Q40 preferred the wording “for the loading conditions on which is based the calculation of a subdivision index” in updating Reg. 8.1. See also responses to Q42, below. 4) We wondered, if new Reg 12.2 is adopted, whether the word “flooded” should be replaced by “damaged” as the flooding would be naturally limited by the equilibrium waterline whereas the vessel could be damaged without vertical limits:“2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 for all service conditions if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded][damaged] without vertical limits.” Q39A - 41A Whilst recognising that further consideration of the full consequences is still needed and that the text of proposed Reg.12.2 may need to be adjusted slightly, would you agree that the advantages of deleting Reg. 8.1 and introducing a new Reg. 12.2 outweigh the disadvantages? Yes MI (with comments), Germany, Finland, Japan, Norway (with comment), CLIA (but this seems to be a cargo ship issue), UK, US, Sweden, Denmark No Further Comments?:MI: Concur, but the proposed text would need to be harmonised with that of 8.2 to read ‘in all service conditions used for calculation of a subdivision index.’ France: Proposed amendment to regulation 12 is not equivalent to paragraph 1 of regulation 8 which generally consider damage cases extending aft from collision bulkhead. The intention was to avoid a large compartment aft from the collision bulkhead. It is assumed that for a damage forward from the collision bulkhead, any ship will survive. Is it really necessary to verify this? For bottom damages, no calculation is required if minimum double bottom height is fulfilled. Norway: Further consideration needed regarding deleting Reg. 8.1. Round 2 Discussion:- Support for deleting regulation 8.1 and introducing a new regulation 12.2 seems unanimous but we had no reply from Spain (who were opposed after round 1) and now France and Norway have expressed concerns in their comments. Many thanks to France for their explanation of reg. 8.1 for which the intent has never been very clear to us. If we do decide to retain this regulation it would seem that a new EN along the lines of France’s comment would be very helpful. We can only suggest that we discuss all this again in the WG at SLF 53. Q39B – 41B. In the light of France’s new explanation of reg. 8.1 do you still favour deleting this regulation and inserting a new regulation 12.2? Yes No

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Further Comments?:POST SLF 53 Note:- Q39B – 41B were discussed in detail in the WG on Thursday afternoon (following completion of the WG paper). It was agreed that all WG discussions from this point onwards at SLF 53 would form the contents of a session document to be prepared and submitted to SLF 54 (ref. SLF 53/19 paragraph 14.9). The conclusion of the debate in the WG was that the issues relating to Reg 8.1 and proposed new Reg. 12.2 should be re-considered by the 2011 CG. Denmark was particularly concerned about the consequences of new Reg. 12.2 on smaller cargo vessels and advised the WG that they would send in some information for consideration by the 2011 CG. Here are some further discussion points for consideration by the 2011 CG as background to the round 4 questionnaire: 1) There now seems to be an increasing feeling that we need both Reg. 8.1 and a new 12.2. Norway originally wanted to delete Reg. 8.1 and introduce a more general requirement covering all ship types under new Reg. 12.2 to the effect that “s” must equal 1 for all damages forward of the collision bulkhead in all loading conditions used in the calculation of an index A. However, Norway now doubts whether we should delete 8.1; Spain and France agree. 2) France has clarified for us the intention of Reg. 8.1 which is to avoid the fitting of a large compartment aft of the collision bulkhead. However, given that several members and the coordinators were not clear that this was the intention of this regulation, we decided to look again to see if the wording could be improved. Perhaps simply changing the words around may help? For example we could change from:1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for the three loading conditions on which is based the calculation of the subdivision index and for a damage involving all the compartments within 0.08L measured from the forward perpendicular. to 1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index. It may also be advisable to add a new EN to explain the intention of this regulation:Regulation 8.1 The intention of this regulation is to prevent the fitting of a large compartment aft of the collision bulkhead. 3) Japan’s original problem was that the requirement that si = 1 for damages forward of the collision bulkhead in SOLAS90 had not been transferred to SOLAS 2009. This applied only to cargo vessels in the probabilistic regulations within SOLAS90 (Reg. 25) but also was indirectly covered for passenger ships through compliance with at least a 1-compartment subdivision standard and specific damage stability criteria. Japan’s problem could then be solved for both cargo and passenger ships by Norway’s proposed new Reg. 12.2:-

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2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits. 4) It would seem from this that both Reg. 8.1 and Reg. 12.2 may be necessary and we simply need to decide on the final wording of Reg. 12.2 (see square brackets above), remembering also that we need to renumber the remaining paragraphs under Reg. 12. 5) Several countries, particularly Germany and Denmark expressed some reservations in the WG about applying proposed new Reg. 12.2 to smaller cargo vessels – we await their comments / data. Q39C – 41C. In the light of the discussion above and at SLF 53, would you agree with the proposed changes to Reg. 8.1 (including the new EN) and the introduction of a new Reg. 12.2 as shown? Yes Vanuatu, Norway, Japan, RINA, Denmark (with comments), Germany, Italy, Finland, UK, France, CLIA, EC (ongoing research might have a bearing on this. Results should be taken into account), Spain (with comments below). No US, China Further Comments / preferred wording for Reg. 12.2 / other alternatives?:US: We fully agree with introducing new regulation 12.2, but with the addition of that new requirement we continue to believe regulation 8.1 is unnecessary and should be deleted. Our rationale is as follows: It is reasonable for all ships required to have a collision bulkhead that there is also a SOLAS requirement that s = 1 for any damage forward of the collision bulkhead; new reg 12.2 will accomplish that. With that addition there will now be a deterministic/ prescriptive requirement for a collision bulkhead and related damage stability survivability for extreme forward damages. Additionally regulation 8.3.2 requires s = 0.9 survivability for a damage case across the collision bulkhead. Under a probabilistic concept, we believe these two additional deterministic/prescriptive requirements in combination are sufficient. Note: reg 8.1 seems to have originated from SOLAS 90 reg II-1/7.3, and is not directly related to the collision bulkhead or 400 persons. Japan: With regard to the words in square brackets, Japan prefers “for the loading conditions on ...”, “the whole position” and “flooded”. RINA: [Preferred wording] The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 for the loading conditions on which is based the calculation of a subdivision index if any part of the ship forward of the collision bulkhead is flooded without vertical limits. The reservations regarding the application of this regulation to smaller cargo ships deserve further examination. See RINA comments in Q6C. Denmark:- Trim range to be covered. This could be outlined in EN. Agree to new EN Reg. 12.2 for cargo ships having a length L > 80 m but we still have reservations on Reg. 12.2 for the very small cargo ships being in mind that this can be cargo ships down to a length of 24 m. Germany: The wording “for the loading conditions on which is based the calculation of a subdivision index” does not apply to vessels which are not subject to B-1, thus should not be used. Generally, throughout SOLAS, the wordings “initial loading conditions di”, “all service conditions”, “all three loading conditions” should be revisited with respect to vessels not subject to B-1 (small cargo and pax vessels, bulker). We suggest using “initial loading conditions di” as

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used in Reg. 7-2.1.1 throughout SOLAS and to specify what is meant by this for vessels not subject to B-1. Finland: We prefer “for the loading conditions on which is based the calculation of a subdivision index if any part of the ship forward of the collision bulkhead is flooded without vertical limits.” Italy: The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 for the loading conditions on which is based the calculation of a subdivision index if any part of the ship forward of the collision bulkhead is damaged without vertical limits. France: For regulation 8.1, we cannot see a real difference with the previous wording? Spain: Support Germany and Denmark - reservations in the WG about applying proposed new Reg. 12.2 to smaller cargo vessels. Round 6 Discussion: We must firstly point out that the WG discussions on this and subsequent questions at SLF 53 now form the contents of a report submitted to SLF 54 (ref. SLF 54/8 dated 30 June 2011) by the Chair of the WG. You are invited to refer to this document when considering the remaining questions. In response to Q39-41C there is now a large majority (13-2) in favour of the proposed changes to reg. 8.1 (including the new EN) and the introduction of a new reg. 12.2. However, there are many comments, some questions and a strong argument for deleting reg. 8.1 altogether. So we will look at all your comments in turn:The US supports new reg. 12.2 but still believes that reg. 8.1, should be deleted because its provisions are covered by reg. 8.3.2 (both are shown below for comparison purposes – amendments already agreed elsewhere in 8.2 and 8.3 are highlighted in red; the proposed amendment for reg. 8.1 with EN is shown ):8.1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index. Regulation 8.1 The intention of this regulation is to prevent the fitting of a large compartment aft of the collision bulkhead. 8.2 A passenger ship intended to carry 36 or more persons is to be capable of withstanding damage along the side shell to an extent specified in paragraph 3. Compliance with this regulation is to be achieved by demonstrating that si, as defined in regulation 7-2, is not less than 0.9 for the three loading conditions on which is based the calculation of the subdivision index. If the subdivision index is calculated for different trims, this requirement must also be satisfied for these loading conditions. 8.3 The damage extent to be assumed when demonstrating compliance with paragraph 2, is to be dependent on both N as defined in regulation 6 the total number of persons carried, and Ls L as defined in regulation 2, such that:

…….. .2

where 400 or more persons are to be carried, a damage length of 0.03 Ls L, but

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not less than 3 m is to be assumed at any position along the side shell, in conjunction with a penetration inboard of 0.1B but not less than 0.75 m measured inboard form the ship side, at right angle to the centerline at the level of the deepest subdivision draught;

New reg. 12.2 applies to all cargo and passenger ships forward of the collision bulkhead whereas reg. 8.1 only applies to passenger ships carrying 400 or more passengers and is designed to ensure that the subdivision is sufficient to ensure that s=1 is achieved at the three standard draughts following damage immediately aft of the collision bulkhead. We are not totally convinced that reg. 8.3.2 is equivalent to reg. 8.1, as the US argues:1) Reg. 8.3.2 covers minor damage only whereas reg. 8.1 covers “all compartments” lying within 0.08L abaft of the forward perpendicular – clearly a major damage scenario with unlimited penetration depth. We think it may be there in case the collision bulkhead is destroyed after a large fore end damage. 2) The required standard for reg. 8.3.2 is si = 0.9 for the 3 standard loading conditions whereas reg. 8.1 requires si = 1 for the same 3 conditions – a significantly higher standard. So reg. 8.1 overall represents a higher safety standard than reg. 8.3.2 for spaces immediately aft of the collision bulkhead. Whether this was the intention is not certain. In this respect we thank the US for drawing our attention to SOLAS 90 reg. II-1/7.3 which is a special requirement concerning passenger ship subdivision:7.3 In ships of 100 m. in length and upwards, one of the main transverse bulkheads abaft the forepeak shall be fitted at a distance from the forward perpendicular which is not greater than the permissible length.

Although we agree with the US that the collision bulkhead is not referred to directly here, it is often the case that the after bulkhead of the forepeak is the collision bulkhead so there may be some correlation here between the intent of II-/7.3 in SOLAS90 and II1/8.1 in SOLAS2009. There does not appear to be any equivalent provision for cargo ships in SOLAS90 – only that s=1 following damage to all compartments forward of the collision bulkhead with unlimited vertical extent, a requirement which we now propose to cover in reg. 12.2. Japan supports the proposal and prefers the following text for new Reg. 12.2: 12.2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits. RINA wants further examination of the application of this regulation to smaller cargo ships and prefers the following text: 12.2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits.

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Denmark asks for trim range to be covered in reg. 8.1 (perhaps in an EN). However we could imply this by deleting [the] below as is already done in some other regulations where calculation of the effect of trim is required:8.1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index. Denmark also shares RINA’s concern on applying reg. 12.2 to small cargo ships which can go down to 24 m in length. We will discuss this below. Germany in reg. 12.2 argues that for the loading conditions on which is based the calculation of a subdivision index could only apply to vessels subject to probabilistic damage stability analysis in part B-1 and suggests that “initial loading conditions di” as used in reg. 7-2.1.1 should be applied throughout SOLAS to replace “all service conditions” and “all three loading conditions” for vessels not subject to the full probabilistic damage analysis (such as small cargo ships etc). We will ask for the views of the group on this idea. Finland prefers the following text for reg. 12.2:12.2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits. Italy prefers the following text for reg. 12.2:12.2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits. France asks why we changed reg. 8.1 FROM 8.1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for the three loading conditions on which is based the calculation of the subdivision index and for a damage involving all the compartments within 0.08L measured from the forward perpendicular. TO 8.1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward

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perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index. This originated from the co-ordinators because, until France explained the true intention of this regulation in round 1, several of us could not really understand the sentence properly. So we proposed the above change to the order of the words to try to remove the word “and” between “subdivision index” and “for a damage” which we felt may have been causing some confusion. We hope the new word order now makes it clearer by putting emphasis on the damage and its extent rather than on the three loading conditions. But we agree – the difference is very small! Spain shares the concerns of Germany, Denmark and RINA about applying new Reg. 12.2 to smaller cargo vessels. SUMMARY 1) We hope that we have been able to convince the US that we still need reg. 8.1 but we will nevertheless ask the group’s opinion. 2) The concerns regarding the applicability of reg. 12.2 to small cargo ships are addressed elsewhere in the wider context of reg. 4.1 (in particular see Q6D). 3) Germany’s proposal to use “initial loading conditions di” wherever the probabilistic damage regulations do not apply would need to be carefully considered in the context of each regulation. We ask the group below whether they approve of this in principle before we highlight all the necessary changes. 4) Regarding text in square brackets:(a) If we agree to retain reg. 8.1 we suggest that we delete [the] and use [a] to denote that trim calculations may be involved. (b) For the square brackets in new reg. 12.2:All 4 members who expressed a preference wanted to delete “for all service conditions”; 3 out of 4 wanted to delete “the whole portion” and 3 out of 4 wanted to delete “damaged”. 5) We include the text changes to reg. 8.1 and 12.2 agreed by the majority below but we recognise that some wider issues, such as the applicability to small cargo ships, US proposal to remove reg. 8.1 (1) and Germany’s proposal (3) still need to be resolved if necessary by the WG at SLF 54. 8.1 A passenger ship intended to carry 400 or more persons shall have watertight subdivision abaft the collision bulkhead so that si = 1 for a damage involving all the compartments within 0.08L measured from the forward perpendicular for the three loading conditions upon which is based the calculation of [the] [a] subdivision index. Regulation 8.1 The intention of this regulation is to prevent the fitting of a large compartment aft of the collision bulkhead. 12.2 The ship shall be so designed that si calculated in accordance with regulation 7-2 will not be less than 1 [for all service conditions] [for the loading conditions on which is based the calculation of a subdivision index] if [the whole portion] [any part] of the ship forward of the collision bulkhead is [flooded] [damaged] without vertical limits.

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Q39D – 41D (for Round 6 questionnaire). 1) Do you agreed with the US in (1) above that reg. 8.1 should be deleted? 2) Do you agree in principle with Germany’s proposal in (3) to use “initial loading conditions di” where appropriate throughout SOLAS? 3) Do you accept the square bracket deletions for reg. 8.1 and 12.2 at the end of the above summary? Yes: US (please see comments) (1) Y/N? No: Japan, CLIA, RINA, Finland, Norway, Germany, Poland, Italy, UK, EC, France, Denmark, China Yes: Japan, CLIA, Finland, Norway, Germany, Italy, Denmark, UK (In (2) principle “yes”, however it is not clear to us what benefits the full proposed Y/N? changes will bring.) No: US, China No comment: RINA Yes: Japan (see comments below), CLIA, RINA, Finland, Norway, China, Germany, EC, France (see comments) No: Italy, Denmark Comment: US (Subject to decision on deleting reg 8.1 - Yes Note: in reg 12.2 we question whether “without vertical limits” is necessary if the text “any part” is added?) Further Comments?:Japan: It is difficult to apply the requirement to small cargo ships because such ships are not applied to Part B-1 and not required to calculate si.. US: Regarding the Round 6 Discussion on keeping or deleting reg 8.1: Although reg 8.3.2 is referred to as “minor damage”, we think that a 0.1B transverse extent and a 0.03L longitudinal extent are less minor in the bow area under consideration. But more significantly, we are not trying to say that reg 8.3.2 is completely equivalent to reg 8.1. What we are saying is that with reg 8.3.2 and the new requirement in reg 12.2, we believe reg 8.1 adds very little additional safety value and is therefore not necessary (i.e. it seems to us that 3 different deterministic regs to cover damage stability in this area is overkill!) France: Cargo ships which are shown to comply with subdivision and damage stability regulation in other instrument will not have subdivision index calculated. So it would be preferable to refer to “all service conditions”. For ships which have to fulfil the stability requirements of part B-1, it will be sufficient to made calculations for the loading conditions on which is based the calculation of a subdivision index. Q39-41D – proposed new EN - see also proposal for reg. 12.2 (3) Y/N?

(1) There was voting of 13-1 against the US proposal to delete Reg 8.1; (2) 8-2 were in favour of Germany’s proposal and (3) 9-2 were in favour of the proposed bracket deletions in reg. 8.1 and new 12.2. IF GERMANY’s PROPOSAL IS ACCEPTED, IT WILL BE NECESSARY TO IDENTIFY WHERE THE PHRASE “INITIAL LOADING CONDITIONS di” SHOULD BE EMPLOYED NOT UNANIMOUS - SO DISCUSS AT SLF 54.

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2 A passenger ship intended to carry 36 or more persons is to be capable of withstanding damage along the side shell to an extent specified in paragraph 3. Compliance with this regulation is to be achieved by demonstrating that si, as defined in regulation 7-2, is not less than 0.9 for the three loading conditions on which is based the calculation of the subdivision index. If the subdivision index is calculated for different trims, this requirement must also be satisfied for [these loading conditions][all loading conditions used for the calculation of the subdivision [indexes][indices]]. [Q42] Regulation 8.2 (ref. SLF 52/17/6 - Norway) Replace the text in paragraph 8.2 to take into consideration that the principle must apply to all calculated trims for the purpose of this paragraph as well: “2 A passenger ship intended to carry 36 or more persons is to be capable of withstanding damage along the side shell to an extent specified in paragraph 3. Compliance with this regulation is to be achieved by demonstrating that si, as defined in regulation 7-2, is not less than 0.9 in all service conditions used for calculation of a subdivision index. R8.2 ( Need to emphasize multiple trims) . Q42. Do you agree to the changes to Reg. 8.2 proposed by Norway, as underlined above? Yes Germany (with comments), Japan, Norway, CLIA, Spain, Denmark, UK, US, Sweden, France (added after Round 2 – with comments) No China, Finland, Italy (with comments) Comments?:China: See comments to Q39. Germany: We support a revised wording as follows “for the three loading conditions on which is based the calculation of a subdivision index”. Italy: Text to be modified as follows : “…by demonstrating that si, as defined in regulation 7-2, is not less than 0.9 for the loading conditions on which is based the calculation of a subdivision index.” France: More general wording applicable if several A index are calculated. Round 1 Discussion: We will need to harmonize the text of Reg. 8.2 either with modified Reg. 8.1 or with new Reg. 12.2, depending on the outcome of Q39A – 41A. Q42A. Any further comments at this stage?:RINA: We can find no definition of service conditions or understand the intent of loading conditions. Both refer to actual ship operational conditions; consequently should they be used in probabilistic calculations. As an alternative we would prefer to use the subdivision draughts ds, dp and dl, all of which are defined in Reg. 2. Note: Service conditions appear throughout this paper. France: Different wording will be necessary for regulation 8 and for possible additional reg. 12.2. Round 2 Discussion: For information, the term “service conditions” is defined in the EN for reg. 9.8:1. The term “all service conditions” used in this paragraph means the three loading conditions used to calculate the attained subdivision index A.

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RINA is correct in saying that the term “service conditions” appears in many places in the regulations, sometimes in different contexts, so perhaps it does merit a definition under regulation 2? Apart from that, we now have 3 proposals for changing reg. 8.2:Original …… is not less than 0.9 for the three loading conditions on which is based the calculation of the subdivision index. 1) Norway …….is not less than 0.9 in all service conditions used for calculation of a subdivision index. 2) Germany …… is not less than 0.9 for the three loading conditions on which is based the calculation of [the] [a] subdivision index. 3) Italy …… is not less than 0.9 for the [three] loading conditions on which is based the calculation of [the] [a] subdivision index. Also, as France says, we will still need to harmonize the text of Reg. 8.2 either with modified Reg. 8.1 or with new Reg. 12.2, depending on the outcome of Q39B – 41B. Q42B (for SLF 53 WG). Please indicate which alternative you prefer and whether you think we need a definition of “service conditions” in reg. 2 No change? 1) Norway? 2) Germany? 3) Italy? New definition of service conditions? POST SLF 53 Note:- Q42B (see working document for background) was discussed in detail in the WG on Thursday afternoon (following completion of the WG paper).The conclusion of the debate was to add the following extra sentence at the end of the regulation If the subdivision index is calculated for different trims, this requirement must also be satisfied for these loading conditions. Q42C (for Round 4 Questionnaire). Have you any final comments on the above? Further Comments?:China: No comments. RINA: No further comment. Denmark: No further comments. Germany: We suggest using “… for these initial loading conditions di” as in reg. 7-2.1.1 to achieve a uniform use of this terminology throughout SOLAS.

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EC: Ongoing research might have a bearing on this. Results should be taken into account. France: Would it be possible to replace “must also be satisfied for these loading conditions” by “must be satisfied for all loading conditions used for the calculation of the attained indexes”. Round 6 Discussion: The WG discussions on this and subsequent questions at SLF 53 now form the contents of a report submitted to SLF 54 (ref. SLF 54/8 dated 30 June 2011) by the Chair of the WG. Germany’s point is noted and is dealt with under Q39D-41D (Q2), above for which we await the outcome. The EC’s comment is also noted – any change agreed now may have to be altered again following completion of the current research projects, which may be another reason for asking the S/C to extend the deadline for this agenda item. France prefers the following wording:2 A passenger ship intended to carry 36 or more persons is to be capable of withstanding damage along the side shell to an extent specified in paragraph 3. Compliance with this regulation is to be achieved by demonstrating that si, as defined in regulation 7-2, is not less than 0.9 for the three loading conditions on which is based the calculation of the subdivision index. If the subdivision index is calculated for different trims, this requirement must be satisfied for all loading conditions used for the calculation of the attained indexes. We will ask the group for their preference; the coordinators’ only comment is that “indexes” should read “indices”, which is, very strictly speaking, the correct plural of index!! Sorry! Q42D (for Round 6 questionnaire). Do you prefer France’s alternative for the last sentence of reg. 8.2 but using “indices” instead of “indexes”? Yes Japan, CLIA, RINA, Norway, Italy, UK, EC, France, Denmark, China No

Finland, Germany, Poland, US

Further Comments?:Germany: How to deal with different trims in various locations of the regs and EN has been discussed in round 5. The result is pending. Poland: Subdivision indexes might be [Could Poland please clarify this? – coordinators] Q42 Voting was 10-4 in favour of France’s proposed deletions and use of “indices” instead of “indexes”. NOT UNANIMOUS SO DISCUSS AT SLF 54 3 The damage extent to be assumed when demonstrating compliance with paragraph 2, is to be dependent on both N as defined in regulation 6 the total number of persons carried [Q43C], and Ls L [Q38] as defined in regulation 2 [Q43C], such that: .1 the vertical extent of damage is to extend from the ship’s moulded baseline to a position up to 12.5 m above the position of the deepest subdivision draught as defined in regulation 2, unless a lesser vertical extent of damage were to give a lower value of si, in which case this reduced extent is to be used; .2 where 400 or more persons are to be carried, a damage length of 0.03 Ls L [Q38], but not less than 3 m is to be assumed at any position along the side shell, in conjunction with a penetration inboard of 0.1B but not less than 0.75 m measured

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inboard form the ship side, at right angle to the centerline at the level of the deepest subdivision draught; .3 where less than 400 persons are carried, damage length is to be assumed at any position along the side shell between transverse watertight bulkheads provided that the distance between two adjacent transverse watertight bulkheads is not less than the assumed damage length. If the distance between adjacent transverse watertight bulkheads is less than the assumed damage length, only one of these bulkheads shall be considered effective for the purpose of demonstrating compliance with paragraph 2; .4 where 36 persons are carried, a damage length of 0.015 Ls L [Q38] but not less than 3 m is to be assumed, in conjunction with a penetration inboard of 0.05B but not less the 0.75 m; and .5 where more than 36, but fewer than 400 persons are carried the values of damage length and penetration inboard, used in the determination of the assumed extent of damage, are to be obtained by linear interpolation between the values of damage length and penetration which apply for ship carrying 36 persons and 400 persons as specified in subparagraphs .4.and .2. Regulations 8.3.2 to 8.3.5 The number of persons carried, which is specified in these paragraphs, equals the total number of persons the ship is permitted to carry (and not N = N1 + 2 N2 as defined in regulation 6). Regulation 8.3.2 to 8.3.5 (ref. SLF 51/3/2 Annex – US and Sweden) Clarify the item that is now addressed in the Explanatory Notes: “The number of persons carried, which is specified in these paragraphs, equals the total number of persons on board (and not N = N1 + 2N2 as defined in regulation 6)” ----------------------------Note: See regulation 12 regarding the issue of a requirement for full survivability (s = 1) in case of damages forward of the collision bulkhead (which is an issue for both passenger and cargo ships).[Co-ordinator’s Note:- See Q39-41, above, for this item.] Regulation 8.3.2 to 8.3.5 (ref. SLF 51/17/5 Annex – Norway) Document SLF 51/3/2 requests a clarification on the following text in the Explanatory Notes “The number of persons carried, which is specified in these paragraphs, equals the total number of persons on board (and not N = N1 + 2N2 as defined in regulation 6)” In the opinion of this Administration the 400 persons is an equivalent to old regulation II1/8-3, which did not take lifeboat capacity into account. The text in the EN is appropriately included to avoid a too stringent application by ensuring that the multiplier 2 will be disregarded for the purpose of this regulation. It is proposed that the text remains as it is.

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R8.3 (Minor damage) R8.3.2 to 8.3.5 EN . Q43. Do you agree with Norway that the current EN does not need amending? Yes

China, Finland, Germany, Japan, MI, Norway, CLIA, Italy, Spain, Denmark

No

Sweden

Comments?:UK: We need further explanation of the intended reason for clarification from ref. SLF 51/3/2 Annex – US and Sweden. US: Sorry but there is a big misunderstanding regarding the intention of this item in SLF 51/3/2. This holding file item was intended to initiate a future amend / fix directly to regulation 8.3, so that the EN could be deleted altogether. i.e. regulation 8.3 should read: “The damage extent... ...is to be dependent on the total number of persons carried and Ls, such that:” Round 1 Discussion: Many thanks to the US for clearing this up. So the proposal now is to change the opening sentence of Reg 8.3 as shown below and delete the EN covering Regs. 8.3.2 to 8.3.5: 3 The damage extent to be assumed when demonstrating compliance with paragraph 2, is to be dependent on [both N as defined in regulation 6] [the total number of persons carried], and [Ls][L] as defined in regulation 2, such that: Q43A. Following the clarification by the US do you now agree to the change in text shown above in Reg. 8.3 and deletion of the EN covering Regs. 8.3.2 to 8.3.5? Yes MI, Germany, Finland, Italy, Japan, France, Norway, CLIA, UK, US (with comment), Sweden, Denmark No Comments?:US: Don’t think we need “as defined in regulation 2”. (This was included before because “N” was defined in reg 6 and therefore needed special reference). Round 2 Discussion: Support is unanimous for this amendment but the US proposes another change which would make the regulation read: 3 The damage extent to be assumed when demonstrating compliance with paragraph 2, is to be dependent on [both N as defined in regulation 6] [the total number of persons carried], and [Ls][L] [as defined in regulation 2], such that: Do you agree to this further amendment? Q43B (for SLF 53 WG). Do you agree that “as defined in regulation 2” can also be deleted along with the EN for reg. 8.3.2 to 8.3.5? Yes No

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POST SLF 53 Note:- Q43B was discussed in the WG on Thursday afternoon (following completion of the WG paper). The conclusion of the debate was to accept the amendments to the opening sentence of regulation 8.3 and delete the EN for Regs. 8.3.2 to 8.3.5 as highlighted above. Q43C (for Round 4 Questionnaire). Have you any final comments on the above amendments? Further Comments?:China: No comments. RINA: No further comment. Denmark: No further comments. France: No further comment.

Q43. CONCLUDED AMENDMENT OF REG 8.3 AND DELETION OF EN8.3.2 TO 8.3.5 TO BE RECOMMENDED AT SLF 54.

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Regulation 8-1 [Note: changes highlighted below agreed at MSC 89/25 (9.10-9.13)] System capabilities and operational information after a flooding casualty on passenger ships 1

Application

This regulation applies to passenger ships constructed on or after 1 July 2010 to which regulation II-2/21 applies. Passenger ships having a length, as defined in regulation II-1/2.5, of 120 m or more or having three or more main vertical zones shall comply with the provisions of this regulation. .[Note: check cross-reference – await outcome of Q66D under reg. 2.26] 2

Availability of essential systems in case of flooding damage *

A passenger ship constructed on or after 1 July 2010 shall be designed so that the systems specified in regulation II-2/21.4 remain operational when the ship is subject to flooding of any single watertight compartment. Regulation 8-1.2 1. In the context of this regulation, “compartment” has the same meaning as defined under regulation 7-1 of these Explanatory Notes (i.e. an onboard space within watertight boundaries). 2. The purpose of the paragraph is to prevent any flooding of limited extent from immobilizing the ship. This principle should be applied regardless of how the flooding might occur. Only flooding below the bulkhead deck need be considered.

3

Operational information after a flooding casualty

For the purpose of providing operational information to the Master for safe return to port after a flooding casualty, passenger ships constructed on or after 1 January 2014 shall have: .1 onboard stability computer; or .2 shore-based support, [in accordance with] guidelines developed by the Organization** [Note: for further consideration and possible adoption at MSC90]

_______________________ * Refer to the Performance standards for the systems and services to remain operational on passenger ships for safe return to port and orderly evacuation and abandonment after a casualty (MSC.1/Circ.1214) [Coordinator’s Note: included below for easy reference]. ** Refer to the Guidelines on operational information for masters of passenger ships for safe return to port by own power or under tow (MSC.1/Circ.1400).

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POST SLF 53 Note:- The changes highlighted in red, above, were agreed at SLF 53 and approved at MSC 89 in May 2011. The new guidelines on operational information for Masters of Passenger ships are included below for easy reference. Note that the cross-reference to regulation II-1/2.5 under “Application” will have to be checked depending on the outcome of Q66D under reg. 2.26

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Note: The following is from SLF 53/WP.6 Annex 3 (now adopted at MSC89 as MSC.1/Circ.1400)

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Part B-2 Subdivision, watertight and weathertight integrity Regulation 9 Double bottoms [in passenger ships and cargo ships other than tankers] [Q6D(4)[1]; discuss at SLF 54] 1 A double bottom shall be fitted extending from the collision bulkhead to the afterpeak bulkhead, as far as this is practicable and compatible with the design and proper working of the ship. Regulation 9.1 1. This regulation is intended to minimize the impact of flooding from a minor grounding. Special attention should be paid to the vulnerable area at the turn of the bilge. When justifying a deviation from fitting an inner bottom an assessment of the consequences of allowing a more extensive flooding than reflected in the regulation should be provided. 2. Except as provided in regulations 9.3 and 9.4, parts of the double bottom not extended for the full width of the ship as required by regulation 9.1 should be considered an unusual arrangement for the purpose of this regulation and is to be handled in accordance with regulation 9.7. Double bottom arrangements as shown in the example below are to be considered as “unusual”, requiring compliance with regulation 9.8.

B/20

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R9.1 EN2 (Unusual DB tanks) CLIA Q14 Additional comments received from CLIA/CCSF between round 1 and 2: Regulation 9.1 EN 2 Additional Explanation: [Double bottom arrangements as shown in the example are to be considered as unusual double bottom arrangement and require compliance with regulation 9.8.2]

B/20

Coordinator’s Comments: Should Reg. 9.8.2 not be Reg. 9.8? CLIA to clarify. Are members happy that the diagram is self-explanatory? CG Member’s Comments?:Germany: Acceptable. Finland: Support. France: Correct reference is Reg 9.8. Term “unusual” is perhaps not adapted for this example. Norway: Supports the clarification if it refers to Reg. 9.8. CLIA: Yes, 9.8 is correct. Round 2 Discussion: There is good support for this proposal from those who responded provided we change the reference to 9.8, although France is not convinced. So, if agreed, EN 2 would now read:2. Except as provided in regulations 9.3 and 9.4, parts of the double bottom not extended for the full width of the ship as required by regulation 9.1 should be considered an unusual arrangement for the purpose of this regulation and is to be handled in accordance with regulation 9.7. [Double bottom arrangements as shown in the example [below] are to be considered as [an] unusual [double bottom] arrangement [and require][requiring] compliance with regulation 9.8[.2]]

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B/20

[Co-ordinator’s Note: One or two minor changes are suggested for your consideration as shown in square brackets].

CLIA Q14. CONCLUDED - PROPOSAL ACCEPTED BY CG. AWAIT APPROVAL BY SUB-COMMITTEE AT SLF 53. (See SLF 53/14 para. 12.7). POST SLF 53 Note: CLIA’s proposal (as amended) was accepted in plenary at SLF 53 (see SLF 53/WP.6 para. 21) and is shown highlighted in grey above. CLIA Q14 (for Round 4 Questionnaire). The coordinators shortened the agreed text from “unusual [double bottom] arrangement [and require][requiring] compliance with regulation 9.8” to that shown above. Is this simplification acceptable? Final Comments?:US: It seems in reality that reg 9.1 EN2 is actually misplaced as it addresses issues related to regulation 9.2 (not regulation 9.1). Further, it seems the sketch is just an example of what the existing EN2 is describing. So we suggest simply indicating “an example is provided below”. Therefore, our proposal is as follows: 1. Relocate and edit current regulation 9.1 EN2 as follows: Regulation 9.2 1 Except as provided in regulations 9.3 and 9.4, parts of the double bottom not extended for the full width of the ship as required by regulation 9.2 should be considered an unusual arrangement for the purpose of this regulation and should is to be handled in accordance with regulation 9.7. An example is provided below. 2. Renumber the existing regulation 9.2 EN to EN 2. China: No comments. Denmark: Simplification is acceptable. Germany: Yes. Finland: Agree. Italy: Agreed. France: Agreement on coordinators’ modification. Round 6 Discussion: There seems to be acceptance amongst those who responded for the slight change to the text but the US would like to relocate EN2 as follows:Currently agreed reg. 9.1 and 9.2 with EN:1 A double bottom shall be fitted extending from the collision bulkhead to the afterpeak bulkhead, as far as this is practicable and compatible with the design and proper working of the ship.

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Regulation 9.1 1. This regulation is intended to minimize the impact of flooding from a minor grounding. Special attention should be paid to the vulnerable area at the turn of the bilge. When justifying a deviation from fitting an inner bottom an assessment of the consequences of allowing a more extensive flooding than reflected in the regulation should be provided. 2. Except as provided in regulations 9.3 and 9.4, parts of the double bottom not extended for the full width of the ship as required by regulation 9.1 should be considered an unusual arrangement for the purpose of this regulation and is to be handled in accordance with regulation 9.7. Double bottom arrangements as shown in the example below are to be considered as “unusual”, requiring compliance with regulation 9.8.

B/20

2 Where a double bottom is required to be fitted the inner bottom shall be continued out to the ship's sides in such a manner as to protect the bottom to the turn of the bilge. Such protection will be deemed satisfactory if the inner bottom is not lower at any part than a plane parallel with the keel line and which is located not less than a vertical distance h measured from the keel line, as calculated by the formula: h = B/20 However, in no case is the value of h to be less than 760 mm, and need not be taken as more than 2,000 mm. Regulation 9.2 If an inner bottom is located higher than the partial subdivision draught dp, this should be considered an unusual arrangement and is to be handled in accordance with regulation 9.7. US Proposal (text changes highlighted in green): 1 A double bottom shall be fitted extending from the collision bulkhead to the afterpeak bulkhead, as far as this is practicable and compatible with the design and proper working of the ship.

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Regulation 9.1 1. This regulation is intended to minimize the impact of flooding from a minor grounding. Special attention should be paid to the vulnerable area at the turn of the bilge. When justifying a deviation from fitting an inner bottom an assessment of the consequences of allowing a more extensive flooding than reflected in the regulation should be provided. 2 Where a double bottom is required to be fitted the inner bottom shall be continued out to the ship's sides in such a manner as to protect the bottom to the turn of the bilge. Such protection will be deemed satisfactory if the inner bottom is not lower at any part than a plane parallel with the keel line and which is located not less than a vertical distance h measured from the keel line, as calculated by the formula: h = B/20 However, in no case is the value of h to be less than 760 mm, and need not be taken as more than 2,000 mm. Regulation 9.2 1. Except as provided in regulations 9.3 and 9.4, parts of the double bottom not extended for the full width of the ship as required by regulation 9.[1][2] should be considered an unusual arrangement for the purpose of this regulation and [should] [is to] be handled in accordance with regulation 9.7. Double bottom arrangements as shown in the example below are to be considered as “unusual”, requiring compliance with regulation 9.8. An example is provided below.

B/20

2. If an inner bottom is located higher than the partial subdivision draught dp, this should be considered an unusual arrangement and is to be handled in accordance with regulation 9.7. CLIA Q14D (for Round 6 Questionnaire). Do you prefer the changes proposed above by the US or those agreed at SLF 53? Japan, Norway, Germany, Denmark, China, US, RoK (prefer the proposed US? changes), UK, France (see comment), RINA (There is not a great deal of difference but prefer the US proposal),

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SLF 53?

CLIA, Finland, Poland, Italy

Comments? France: We don’t see a significant difference CLIA Q14 8 members fully support the US proposal and another 2 support it but do not see much difference with the other alternative. 4 members prefer to keep the text and diagrams agreed at SLF 53. NOT UNANIMOUS - FINAL DECISION TO BE MADE AT SLF 54 2 Where a double bottom is required to be fitted the inner bottom shall be continued out to the ship's sides in such a manner as to protect the bottom to the turn of the bilge. Such protection will be deemed satisfactory if the inner bottom is not lower at any part than a plane parallel with the keel line and which is located not less than a vertical distance h measured from the keel line, as calculated by the formula: h = B/20 However, in no case is the value of h to be less than 760 mm, and need not be taken as more than 2,000 mm. Regulation 9.2 If an inner bottom is located higher than the partial subdivision draught dp, this should be considered an unusual arrangement and is to be handled in accordance with regulation 9.7. 3 Small wells constructed in the double bottom in connection with drainage arrangements of holds, etc., shall not extend downward more than necessary. In no case shall the vertical distance from the bottom of such a well to a plane coinciding with the keel line be less than 500 mm. A well extending to the outer bottom is, however, permitted at the after end of the shaft tunnel. Other wells (e.g., for lubricating oil under main engines) may be permitted by the Administration if satisfied that the arrangements give protection equivalent to that afforded by a double bottom complying with this regulation. In no case shall the vertical distance from the bottom of such a well to a plane coinciding with the keel line be less than 500 mm. [Post SLF 53 Note:- The above changes were initiated by the SLF 53 WG and later approved in plenary (Ref:- SLF 53/WP.6 paragraphs 27 and 28 for the rationale)].

[Co-ordinator’s Note:- NEW QUESTION FROM GERMANY FOR 2011 CG] R9.3 (Proof of “equivalent protection” is needed) Post SLF 53 Comments:- Clarification regarding “equivalent protection” as mentioned in Reg. 9.3 was verbally agreed by the SDS-WG in SLF 53, namely to show compliance with the requirements laid down in Reg. 9.8.

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Germany proposes adding the following sentence in Reg. 9.3 (new text highlighted). Other wells (e.g. for lubricating oil under main engines) may be permitted by the Administration if satisfied that the arrangements give protection equivalent to that afforded by a double bottom complying with this regulation. Proof of equivalent protection is to be shown by demonstrating that the vessel is capable of withstanding bottom damages as specified in paragraph 8. Q65D. Do the members agree to adding this sentence? Yes?

No?

France, CLIA, Finland, Norway, Germany, US, UK, China, Denmark, RoK (agree), EC (Seems OK), IACS (can generally support the German proposal. However, “small wells” should be clarified in the same way "other wells" have been clarified) Japan (see comments below), RINA (see comments), Italy

Comments:Japan: Japan in general agrees with the concept made by Germany to require the compliance with Reg. 9.8, as the proof of equivalent protection, for well with vertical height between the well bottom and baseline less than 500mm. Small ships normally can not provide with other wells complying with the minimum height of 500mm as required by Reg. 9.3. Subsequently, SDS WG in SLF53 agrees to amend Reg. 9.3 to limit the 500mm clearance restriction to small double bottom well. Actually, even any size of ships do not have other well only for LO Sump tank with vertical height of greater than B/20 (min. 760mm / max.2000mm) as required by Reg. 9.2. In the same manner as the problem caused in small ships, such a well less than 500 mm in height should be demonstrated to withstand bottom damages as specified Reg.9.8. Based on above, Japan would propose further modification to Reg. 9.3 as follows; “Small wells constructed in the double bottom in connection with drainage arrangements of holds, etc., and other wells (e.g. for lubricating oil under main engines) shall not extend downward more than necessary. In no case shall the vertical distance from the bottom of such a well to a plane coinciding with the keel line be less than 500 mm. However, in case that the vertical distance from the bottom of such a well to a plane coinciding with the keel line is less than 500 mm, proof of equivalent protection is to be shown by demonstration that the vessel is capable of withstanding bottom damages as specified in paragraph 8. A well extending to the outer bottom is, however, permitted at the after end of the shaft tunnel. Other wells (e.g. for lubricating oil under main engines) may be permitted by the Administration if satisfied that the arrangements give protection equivalent to that afforded by a double bottom complying with this regulation. In no case shall the vertical distance from the bottom of such a well to a plane coinciding with the keel line be less than 500 mm.” RINA: We prefer that the requirements for equivalent protection / not impair the safety of the ship in 9.3/9.4 are incorporated in the proposed amendment to 9.8 below: 9.8. Compliance with paragraphs 3, 4, 6, or 7 is to be achieved by demonstrating that si, when calculated in accordance with regulation 7-2, is not less than 1 for all service conditions when subject to a bottom damage assumed at any position along the ship’s bottom and with an extent specified in subparagraph .2 for the affected part of the ship:

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Q65 Voting was 12-3 in favour of the proposal by Germany. Japan, RINA and IACS all have significant comments, however. FURTHER DISCUSSION NEEDED AT SLF 54 Regulation 9.3 (ref. SLF 51/3/5 – IACS) [Coordinator’s Note:- This paper, proposing a basis for an interpretation to the requirement for the DB height under the main engine, was not supported (ref. SLF51/WP.1 paragraph 6)]. 4 A double bottom need not be fitted in way of watertight tanks, including dry tanks of moderate size, provided the safety of the ship is not impaired in the event of bottom or side damage. [New Coordinator’s Note for SLF53:- Concern has been expressed that LO drain tanks or sump tanks may have open tops, often not clearly marked on drawings. How should these be treated?]. [Post SLF 53 Note:- The above was discussed by the WG. Germany showed slides, highlighting the design difficulties for smaller vessels with low double bottom heights. ] 5 In the case of passenger ships to which the provisions of regulation 1.5 apply and which are engaged on regular service within the limits of a short international voyage as defined in regulation III/3.22, the Administration may permit a double bottom to be dispensed with if satisfied that the fitting of a double bottom in that part would not be compatible with the design and proper working of the ship. [Q6D(3)] [Asks members’ opinion in general on the degree to which regs. 9.6 through 9.8 should be applied to small dry cargo ships – various options are given. Option(a) reduce s=1; 5 in favour; (b) introduce flexibility; 3 in favour (c) do not apply to small cargo vessels; 2 in favour US and Japan comments; Option (d) other alternatives from RINA and Norway. See SLF 54/8/1 para. 14.2. Discuss at SLF 54] 6 Any part of a passenger ship or a cargo ship that is not fitted with a double bottom in accordance with paragraphs 1, 4 or 5 shall be capable of withstanding bottom damages, as specified in paragraph 8, in that part of the ship. [This does not apply to small dry cargo ships.] [Q6D(4)[2]; discuss at SLF 54.] Regulation 9.6 1. Any part of a passenger ship or a cargo ship where a double bottom is omitted in accordance with regulation 9.1, 9.4 or 9.5 shall be capable of withstanding bottom damages, as specified in regulation 9.8. The intent of this provision is to specify the circumstances under which the Administration should require calculations, which damage extents to assume and what survival criteria to apply when double bottoms are not fitted. [This does not apply to small dry cargo ships.] [Q6D(4)[2] discuss at SLF 54]

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2. The definition of “watertight” in regulation 2.17 implies that the strength of inner bottoms and other boundaries assumed to be watertight should be verified if they are to be considered effective in this context. 7 In the case of unusual bottom arrangements in a passenger ship or a cargo ship, it shall be demonstrated that the ship is capable of withstanding bottom damages as specified in paragraph 8. [This does not apply to small dry cargo ships.] [Q6D(4)[4] discuss at SLF 54] Regulation 9.7 The reference to a “plane” in regulation 9.2 does not imply that the surface of the inner bottom may not be stepped in the vertical direction. Minor steps and recesses need not be considered unusual arrangements for the purpose of this paragraph as long as no part of the inner bottom is located below the reference plane. Discontinuities in way of wing tanks are covered by regulation 9.4.

8 Compliance with paragraphs 6 or 7 is to be achieved by demonstrating that si, when calculated in accordance with regulation 7-2, is not less than 1 for all service conditions when subject to a bottom damage assumed at any position along the ship's bottom and with an extent specified in subparagraph .2 below for the affected part of the ship: .1

Flooding of such spaces shall not render emergency power and lighting, internal communication, signals or other emergency devices inoperable in other parts of the ship.

.2

Assumed extent of damage shall be as follows: For 0.3 L from the forward perpendicular of the ship 1/3 L2/3 or 14.5 m, whichever is less B/6 or 10 m, whichever is less

Longitudinal Extent Transverse Extent Vertical Extent, B/20 or 2 m, whichever is less measured from the keel line

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Any other part of the ship 1/3 L2/3 or 14.5 m, whichever is less B/6 or 5 m, whichever is less B/20 or 2 m, whichever is less

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.3

If any damage of a lesser extent than the maximum damage specified in sub-paragraph .2 would result in a more severe condition, such damage should be considered.

Regulation 9.8 (ref. SLF 51/3/2 Annex – US and Sweden) The assumed extent of damage; the longitudinal and vertical extent is the same all along the ship. This should be verified referring to damage statistics. R9.8 R9.8 EN . Q44. Do you think that the extents of damage in this Regulation need to be rechecked? Yes No

Japan (but see proposal), Norway, Spain (see comment), UK, Sweden, France (added after Round 2) Finland, MI, CLIA, Italy, Denmark

Comments?:China: The damage extent of Reg.9.8 is similar to the bottom damage extent of IBC, IGC and MARPOL. Finland: Not until verified damage statistics are available. Refer to GOALDS. Germany: No, until other evidence is available (results GOALDS). Japan: Japan concurs with this proposal. The requirement “si is not less than 1” should also be reconsidered referring to the statistics. Japan also thinks that the alternative regulation regarding bottom damage could be accepted like as side damage (paragraph 4.1). Please find attached file (Q44 proposal.doc, included below for easy reference):Japan proposes amendments of SOLAS II-1/9.8 and EN as follows. Proposal amendment of SOLAS II-1 Add following sentences as footnote in SOLAS II-1/9.8. ----* In the case of ships which comply with the regulations shown in the footnote of paragraph 4.1, the assumed bottom damage as specified in paragraph 9.8.2 shall be applied to all conceivable locations along the length of the ship between adjacent transverse bulkheads. Where the damage between adjacent transverse watertight bulkheads is envisaged, no main transverse bulkhead or a transverse bulkhead bounding side tanks or double bottom tanks shall be assumed damaged, unless: .1 the spacing of the adjacent transverse bulkhead is less than the longitudinal extent of assumed damage specified in regulation 9.8.2; or .2 there is a step or recess in a transverse bulkheads of more than 3.05m meters in length, located within the extent of penetration of assumed damage. ----Proposal amendment of Explanatory Note Add the following sentences (underline) to the explanation in paragraph 9.8.2 of EN.

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---2. The damage extents specified in this paragraph should be applied to all parts of the ship where no double bottom is fitted, as permitted by regulations 9.1, 9.4 or 9.5, and include any adjacent spaces located within the extent of damage. Small wells in accordance with regulation 9.3 do not need to be considered damaged even if within the extent of the damage. Possible positions of the damages are shown in an example below (parts of the ship not fitted with a double bottom are shaded; the damages to be assumed are indicated by boxes).

In the case of ships which comply with the regulations shown in the footnote of paragraph 4.1, the term “at any position” used in this paragraph means anywhere in the ship’s length between adjacent transverse bulkheads, unless: .1 the spacing of the adjacent transverse bulkhead is less than the longitudinal extent of assumed damage specified in regulation 9.8.2; or .2 there is a step or recess in a transverse bulkheads of more than 3.05m meters in length, located within the extent of penetration of assumed damage. Possible positions of the damages are shown in an example below (parts of the ship not fitted with a double bottom are shaded; the damages to be assumed are indicated by boxes).

Background SOLAS II-1/4.1 accepts the regulations listed in the footnote, ex. MARPOL 73/78 etc., as alternative regulations in part B-1 (side damage stability). Regarding the tank shown below, side damage indicated by blue boxes would cause the same flooding caused by bottom damage indicated by red boxes. Accordingly, in the case of ships which comply with the regulations shown in the footnote of paragraph 4.1, the same assumptions in accordance with MARPOL / LL could also be accepted in the case of bottom damage (paragraph 9.8).

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End of Japan’s Proposals Norway: A further investigation could be useful to clarify the extent of damage. Please note that the distribution shown on page 3 of Annex 1 to SLF 47/INF.4 indicates that a change could be justified. The number of data points in these statistics is perhaps too low to draw firm conclusions. Spain: It could be verified referring to damage statistics. Anyway, if the damage statistics confirm the suggested differences, we think that it is better to define only two zones (forward part and rest of the ship), for simplicity reasons. UK: We support re-checking, and consider that in particular the vertical extent needs to be revised. US: Only if additional information is available; we believe the GOALDS project is looking at this issue. Round 1 Discussion: Opinion on the issue of carrying out further investigations into the statistics underlying the extent of bottom damage regulations is evenly divided (5/5) – many thanks for the comments and proposals received, in particular the detailed ideas for an additional footnote and extended EN from Japan. Several members think that we need further investigation if additional information becomes available (perhaps via the GOALDS project) whereas Norway thinks that change may be justified on the basis of the distribution in Annex 1 of SLF 47/INF.4 if more data points are now available. Proposed Action: As it seems that there is sufficient concern for this matter to be taken further but some consider that we need more data to do this properly, it is proposed that we flag up the issue to the SLF sub-committee recommending further discussion either at SLF 54 or when more statistical data becomes available (perhaps via GOALDS). In the meantime we invite your thoughts and comments on Japan’s proposals which could perhaps be used as an interim measure. Q44A Do you agree with the proposed action, above? Yes

MI, Germany, Finland, Japan, France (with comments), Norway, CLIA, UK, US, Sweden, Denmark

No Comments (particularly on Japan’s proposal) / Alternatives?:Italy: Further input may come from GOALDS. However we do not support any interim measure. France: GOALDS project effectively deals with this question. Japanese proposal would lead to consider the flooding of only one compartment which is not equivalent to present reg 9. According to Q6A, ship of less than 80m may be excluded.

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Round 2 Discussion: Support was unanimous for the proposed delay, which has been included in the CG report (ref. SLF 53/14 paragraph 13.5) so we will await the decision of the S-C. We could, however, discuss Japan’s proposed amendments to the EN further with the other members in the WG (France and Italy do not fully support it). Q44B (for SLF 53 WG) Whilst we await the decision of the S-C regarding the proposed delay to discussion of this item until more bottom damage data is available do you in the meantime support Japan’s proposed amendments to the EN? Yes No Post SLF 53 Notes:- There was considerable debate in the WG on Reg. 9.8, especially now that it has been agreed that regulation II-1/9 applies to cargo ships of less than 80 m in length. In the end the matter was returned to us in the 2011 CG (ref. SLF 53/WP.6 paragraph 26) with the following ToR:SLF 53/WP.6 paragraph 32.5 - “consider the validity of applying sub-paragraph 9.8 to smaller ships and, if necessary, suggest appropriate amendments”. Discussion also turned to the phrase “for all service conditions”. Germany and Denmark were concerned that this could involve undertaking the calculation for scores of conditions; both members stated that they would submit papers either to the CG or to SLF 54. Discussion Notes for 2011 SDS CG: 1) With regard to the original request for confirmation of the extents of damage we will continue to await the conclusions of the GOALDS project but we may need to find out from the project leaders when we can expect this work package to be completed so that we can conclude our deliberations in time for SLF 54, in Jan 2012. Norway mentioned that we may be able to do some work on this ourselves using the distribution in Annex 1 of SLF 47/INF.4 if more data points are now available. Could Norway take this any further for us? 2) We need to ask your opinion on the phrase [for all service conditions]. Denmark, we believe, has an alternative proposal (and Germany?). 3) Can we apply Reg. 9.8 to cargo vessels of less than L = 80 m? 4) Recalling the amendments now agreed to Reg. 4.1 which now only relate to Part B-1 (see Q6B):1 [In Part B-1, .1 regulation 5 shall apply to passenger ships of all sizes and every cargo ship having a length (L) of 24 m and upwards (including tankers covered by MARPOL Annex 1, the IBC and IGC Code). .2 regulation 5-1 shall apply to passenger ships of all sizes and every cargo ship having a length (L) of 24 m and upwards including those vessels which are shown to comply with stability regulations in other instruments* developed by the Organization but shall not apply to tankers covered by MARPOL Annex 1, the IBC and IGC Code. .3 the remaining regulations in Part B-1 shall apply to passenger ships of all sizes and, with the exception of regulations 8 and 8-1, to cargo ships having a length (L) of 80 m and upwards but they shall not apply to any vessels which are shown to comply with subdivision and damage stability regulations in other instruments* developed by the Organization.]

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__________________ Do you think that a footnote of some sort is now needed for Part B-2 to clarify the application, once we decide on the appropriate length for dry cargo vessels? The footnote proposed below was rejected at SLF 53 but it is still felt that something similar may be necessary. [* The regulations in Part B-2 apply to passenger ships regardless of length and to cargo ships of [24][80] m in length (L) and upwards but shall not apply to those cargo ships which are shown to comply with subdivision and damage stability regulations in other instruments developed by the Organization (Ref. footnote to Regulation 4.1).]

Q44C (for Round 4 Questionnaire):a) Can we do anything ourselves about the extents of damage before GOALDS reports its findings? b) Should we change “for all service conditions”? c) Should we apply Reg. 9.8 to cargo vessels of less than 80 m in length L? d) Do we need a new footnote to Part B-2 clarifying the application, similar to that in Part B-1? Bear in mind the Germany/UK paper to MSC (Ref. MSC 89/22/8). e) Are there any further comments on Japan’s proposals for changing the EN? France stated under Q44A that “the Japanese proposal would lead to consider the flooding of only one compartment which is not equivalent to present reg. 9.” a)

Please comment on each question below. US (No comment), Vanuatu (No opinion) Norway (The database material in SLF 47/INF.4 is probably to small to complete a probabilistic revision for the double bottom damage. Norway invites the members of the correspondence group to submit any data that they may have that can contribute to the SLF 47/INF.4 sample). Japan (Yes. We could consider the scope to be applied reg 9.8). Sweden, UK, Spain and RINA (Prefer to await the results of the GOALDS report). Denmark (For small cargo ships we can investigate if existing designs being built within the last 5 years have a double bottom fitted according to Reg. 9 requirements and, if not, whether they fulfil Reg. 9.8. Further, have a look on the existing damage statistics). Germany, Finland, France, Italy: (No).

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b)

c)

Vanuatu (phrase seems clear enough) US (Yes; the reg 9.8 text “all service conditions” should be revised to reflect the existing EN1 text “the three loading conditions used to calculate the attained subdivision index A”. Then reg 9.8 EN 1 can be deleted). Norway (Propose to change from “all service conditions” to “the three loading conditions used to calculate the attained subdivision index A” and delete the EN). Japan, France (No) China (There is no need to change it). RINA (Note that the term is already explained in EN 1:“The term “all service conditions” used in this paragraph means the three loading conditions used to calculate the attained subdivision index A.”) Denmark (It must be outlined that the conditions should cover the operational trim range). Germany (We suggest using “initial loading conditions di“ as used in Reg. 7-2.1.1 throughout SOLAS and to specify what is meant by this for vessels not subject to B-1). Finland (Prefer to use instead of “for all service conditions”, “the loading conditions on which is based the calculation of a subdivision” index.”) Italy (Keep the term as already explained in EN1). UK (Would prefer to solve this probabilistically, where possible i.e. avoid use of any other prescriptive loading conditions). Vanuatu (No. As previously stated, we believe application of 9.8 to beamy vessels would not benefit the process). US (No; this would not seem consistent as there is no collision/side damage requirement for these cargo ships). Norway, UK (Yes). Japan (thinks that it seems difficult for cargo ships with L 0.00) should also be submitted for passenger ships and ro-ro ships fitted with long lower holds including full details of the calculated factors. 2.3.2

Special consideration

For intermediate conditions as stages before cross-flooding or before progressive flooding, an appropriate scope of the documentation covering the aforementioned items is needed in addition.

THE FOLLOWING APPENDICES RELATE TO REGS 5-1 to 7.2: APPENDIX 1)

Norway’s original proposals

APPENDIX 2)

Current clean text of SOLAS 2009 and EN

APPENDIX 3)

Alternative proposals by UK

APPENDIX 4)

Round 5 discussions and questionnaire results

APPENDIX 5)

Norway’s revised proposals for discussion at SLF 54

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APPENDIX 1 [Co-ordinator’s Note: In view of the major re-organisation proposed by Norway to the regulations and explanatory notes covering Regulation 5-1 (Stability Information to be supplied to the master) and Regulation 7 (the attained subdivision index, A) a revised text is shown below with all comments removed for ease of reference. Norway’s proposed changes to the Regulations are shown in blue and alterations to the EN in italic font. Appendix 2 shows the current SOLAS Consolidated Edition 2009 and EN for comparison. Appendix 3 shows an alternative set of proposals].

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Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) and maximum permissible trim versus draught which assures compliance with the relevant intact stability requirements of part A of the 2008 IS Code and relevant damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability according to the requirements of part A of the 2008 IS Code and stability after damage.

Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information.

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456); Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706);[Q6] and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/− 0.5% of [Ls] [L]. Applied trim values shall coincide in all stability information intended for use on board. [Coordinator’s Note for Round 2: Not yet finally decided - please see Q20(a)A, Q20(b)A and Q20(c)A for further questions on this Regulation in Round 2]

4 The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations. Information not required for determination of stability and trim limits should be separated from this information. 5 If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If it is intended to develop curves of maximum permissible KG it shall be ensured that the resulting maximum KG curves correspond with a linear variation of GM. 6 When curves or tables of minimum operational metacentric height (GM) versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition. Regulation 5-1.3, 5-1.4 and 5-1.5 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated.

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3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

4 As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed at the deepest subdivision draught ds and the partial subdivision draught dp respectively. The lowest values of each partial index As and Ap across trims will then be used in the summation of the attained subdivision index A according to regulation 7.1. At the light service draught the partial index Al is assumed constant. This will result in one GM limit curve based on the GM used at each draught. A trim limit diagram showing the assumed trim range is then developed as shown in the figure.

[Coordinator’s Note:- Is the above diagram understandable to everybody? For example, what does the vertical axis represent – minimum GM? What happens if KG is used?]

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5 It is not required that the trim values at ds and dp coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked at 0.5% Ls [L] in excess of the largest calculated trims as shown in the figure. There will be no trim limits in the draught range between dl and dp unless the limiting GM is governed by other applicable intact or damage stability criteria. ----------------------------------------Q21. Looking at Regulation 5-1.4 and the EN, it would appear that the amendments proposed in SLF 51/3/2 have been superseded by Norway’s proposals in SLF 52/17/4 and 52/17/6. The EN amendment in 51/3/2 would then be superseded by Norway’s revised EN, which also includes alterations to Reg. 7. A clean copy of all the proposed SOLAS text revisions and the changes to the EN are shown in Appendix 1 at the end of this questionnaire. Taking into account all the comments and notes above would you agree to the amendments to Regulation 5-1 with EN as proposed by Norway and as shown in Appendix 1? Yes No

China (but amended diagram needed), Finland (with comment), Germany (with comment), Japan, MI, Norway, Italy (with comment), US (with comment), Sweden CLIA, Spain, Denmark, UK

Comments / Alternative Proposals?:China: Reference is made to the trim limiting curve on page 3 of the annex of document SLF 52/17/4 Norway . Following figure is a hard-copy:

This is a good proposal except that the two slope lines should be vertical and the trapezoid curve should be rectangular as the proposed figure by Norway uses two different sets of trim range

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in the calculation of partial index A for draught dp and ds respectively. Paragraph 2 of notes to Regulation 5-1.3 and 5-1.4 of MSC.281(85) says “then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading condition of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded”. I interpret this sentence in this way: draught dp and ds represent cargo loading conditions. “Operational range of trims” is the trim range starting from the least trim to the maximum trim on the sorted results of the trims of all cargo loading conditions. For example, if the real trims(i.e., without deduction of ±0.5%Ls for all cargo loading conditions are sorted and listed as below: -1.7%Ls, -0.4% Ls, 0.8% Ls, 1.6% Ls, 2.4% Ls Then the real trim range is -1.7% Ls ~2.4% Ls. Trim range of -1.2% Ls ~1.9% Ls. range should be applied in the calculation of partial index A for both dp and ds. This means the trim range of dp is the same as the trim range of ds. Although for the cargo loading conditions in the loading manual, the range of trims of the loading conditions of which the draft is ds may differ from the trims range of the loading conditions of which the drafts are less than ds, but in real operation the loading conditions may differ from the loading manual and the real trims of ds may exceed the used trim range and run into the trim range of dp. And the same case may occur for the used trim range of dp. Therefore using two separate trim ranges for draught dp and ds respectively is only of theoretical meaning and may not be consistent with the real operation. However, using the same trim range for both draught dp and ds as illustrated above is practical and concords with the explanatory notes. END of CHINA’s PROPOSALS Finland: Reg 5-1.4 (proposed 5-1.5, see Q18). Propose to add ; “If the subdivision index is calculated for different trims, an envelope curve with the highest GM values of the several required GM curves will be established in the same way. Agree with Norwegian proposed text into EN with the exception that calculations for trim variation also include variable trim for dl. Germany: has the following comments (the wording of the proposed text by NOR would need to be revised at several parts (including the diagram)!) c) We regard it as NOT meaningful that the light service draft dl is “fixed” in draft/trim (as a consequence Al is constant). Such restriction is in conflict with the general methodology of the probabilistic concept Î we regard dl as a “design parameter” which can be freely chosen by the designer. This includes that calculations for trim variation also include variable trims for dl. Any load cases need later to be verified to be within the limitations of trim/GM as a result of the damage stability calculation. This allows full flexibility for the designer and also inherits the required safety level d) With respect to Reg. 5.1.5 and the diagram we have the following comments: It is proposed that in the draft range between dl and dp NO trim limitation is valid. We are concerned for drafts close below dp as here per proposed definition no limit exists. We regard it as important that the trim limitation of +/- 0.5%L is valid for the entire draft range. This is to be seen in conjunction with our proposal that trim variations for dl are allowed. MI: Proposals acceptable as a complete package including use of ‘L’.

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Norway: It is realised that the second figure may be difficult to explain, however the principle for dealing with draughts below dp can not be dealt with without considering the effect on A and the calibration of the R-formulas. CLIA: This issue and the EN is handled in the CSSF work:The calculation of different trims as proposed by Norway (SLF52/17/4) is shown below in a slightly simplified way and supported by the group. The concept of fixed trim at the light service draught has been removed and the normal trim range of 0.5% Ls is also applied here. However more examples might be useful in the final EN to illustrate the concept, in particular for trim variations at draughts between dl and dp. “3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7 an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations 4 As an alternative to an envelope curve the calculations for additional trims may be carried out with one common GM for all of the trims assumed at the deepest subdivision draught ds and the partial subdivision draught dp respectively. The lowest values of each partial index As and Ap across trims will then be used in the summation of attained subdivision index A according to regulation 7 5 It is not required that the trim values at ds, dp and dl coincide as long as the limitations with respect to variation between trims are observed at each draught.” Italy: Yes in principle but the lack of trim limits in the draught range between dl and dp is not acceptable. Spain: We do not agree with the proposal contained in points .4 and .5 (“As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed...”). The proposed limiting trim curve is not very clear for us. Anyway, if the group decides to accept the proposal, we have two comments: 3) What are the trim limits between dl and dp? 4) We suggest to change the axis (e.g. draught X axis and trim Y axis):

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END of SPAIN’s COMMENTS Denmark: In terms of presentation, I would be concerned that the trim limit diagram will be potentially confusing to ship’s staff, we prefer UK’s proposal for a trim limit diagram. Also Reg 51.5 should be the maximum of minimum GM limit curves. EN 3, Ls should be changed to L for consistency? We agree with the principle to clarify the regulations, but think that the presentation of max trim needs to be improved. UK: We are of the opinion that the details of each trim value used in the calculations should be presented as separate curves, alongside with the envelope curve (see Q25). US: Yes in principle; however some details need to be further considered and refined. e.g. The relationship between proposed new regulation 5-1.4 and the existing provision in regulation 5-1.2 is unclear to us; should these paragraphs be consolidated or should paragraph 4 precede paragraph 2? Also as indicated in the Coordinator’s Note, the new figure for EN paragraph 4 needs additional details / clarifications. Round 1 Discussion: See end of Appendix 1 for general discussion on the issues raised by Q21, Q23 and Q25.

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Regulation 7 Attained subdivision index A 1 An attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula:

i=t Ac = ∑ pi [vi si] i=1

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2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating each index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. The light service condition will be common for all calculations of index A.

Q23.

Do you agree with the proposed changes to Reg 7.1.5 EN (shown in blue)?

Yes

China, Finland, Japan, Norway, Spain, Denmark, Sweden

No

Germany, MI, Italy, UK, US

Comments?:China: Propose to replace “mean draught d” with “correspondent draught d” as color text below: “5 Three initial loading conditions should be used for calculating each index A. The loading conditions are defined by their meancorrespondent draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. The light service condition will be common for all calculations of index A.”

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Germany: Refer to our answer to Q21. CLIA: See CSSF EN for this issue. Italy: Not acceptable because there may be loading conditions corresponding to light service draught with different trims. US: We prefer the original text; this EN is describing the general case. Round 1 Discussion: See end of Appendix 1 for general discussion on the issues raised by Q21, Q23 and Q25. 6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. 7 A previously approved partial index Al may be considered to remain valid for a sister ship and in other cases where differences in light ship particulars result in minor deviations from the assumed draught and trim in the light service condition. It is recommended that the limits for validity of stability documentation in case of lightship deviations set out in regulation 5.2 be applied also for this purpose.[Coordinator’s Note: Please see Q24A for possible amended version of this text]. 2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The [actual] [anticipated] service trim shall be used for the light service draught dl. If in any anticipated service condition within the draught range from ds to dp the trim variation in comparison with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of A are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. The partial index Al is considered constant for the purpose of these calculations. [Regulation 7.2 EN removed] 3 Each additional value of A calculated in accordance with paragraph 2 shall comply with regulation 6 and 7.1. Q25. Norway proposes to replace the existing text of Reg 7.2 and re-organize and re-number the remaining regulations and EN in association with Reg 5-1.4 (see Appendix 1 for complete version). It is assumed that these amendments are intended to replace Norway’s earlier proposals in SLF 51/3/2. An alternative proposal from the UK in 51/3/2 suggests that maximum allowable KG’s rather than minimum GM’s should be used and that the limiting curves should be presented as a variation against trim for the 3 specified draughts (assuming linear interpolation between draughts). Combined critical KG curves would then cover all the relevant stability criteria, both intact and damage. No specific

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changes to the text of the Regulations or EN were proposed. As this is a fairly complex issue we would simply like to ask if there is support at this stage for Norway’s package of proposals for Reg 7 as shown in Appendix 1; are there any objections, questions or alternative proposals? Yes (Accept Norwegian proposals in App 1)

China, Finland, Germany, MI (but see comments), Norway, Italy, US

Japan, Spain (see comments), Denmark, UK, Sweden No Comments, reasons, alternative proposals?:Finland: Support Norway. No support for UK proposal. Prefer GM-limiting rather than KGlimiting curves. Germany: Support Norway’s proposal (strong objections against UK proposal!) Japan: It is not clear how to deal the case that the trim in the loading case between Dp and Dl exceeds the range of calculated trim. MI: Could support Norway’s proposals because they are in a package but the UK suggestion of using max allowable KGs and resulting combined critical KG curves has considerable merit and should be further discussed before a final decision is made. CLIA: CSSF EN work. Italy: See also comments on item 21. Spain: We accept the proposals except the trim versus draught graph. As we have explained, it is not very clear in our opinion. We have made one proposal: -

To change the axis (e.g. draught X axis and trim Y axis):

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Spain (continued): Regarding UK proposal, we think it is more clear than the other proposed trim limit curve (we can accept it), but we think that for the master is more intuitive to have GM or KG curves versus draught (and different curves depending on trim), e.g.: Max Allowable KG vs Draught Trim Aft

Trim 0

Trim Fwd

8.5 8

Critical KG (m.)

7.5 7 6.5 6 5.5 5 4.5 4 4

4.5

5

5.5

6

6.5

7

Draught (m.)

End of Spain’s Proposals

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Denmark: We wonder if it is worth considering whether the trim limits should be restricted to no greater than the calculated conditions, as it is for deterministic damage stability. Consider that if the partial indices are at 0.5R or 0.9R for a particular trim, allowing 0.5%L more trim will most certainly reduce the attained partial indices. US: We support in principle; details subject to further consideration. Round 1 Discussion: See end of Appendix 1 for general discussion on the issues raised by Q21, Q23 and Q25. 4 When determining the positive righting lever (GZ) of the residual stability curve, the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. 5 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 6 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.6 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only to the centreline and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads.

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7 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed in the final stage of flooding. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. 8 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.8 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total cross-sectional area of not more than 2

710 mm between any two watertight compartments. General Discussion on Q21, Q23 and Q25 covering:1. Reg. 5-1.4 (Stability information to be supplied to the master) and associated EN 2. EN 5 for Reg. 7.1 (Attained subdivision index A) 3. Reg. 7.2 and associated EN for the trims to be used in the calculation of A As coordinators we have found it quite difficult to draw any firm conclusions from the responses made to date on how best to present the results of the S2009 damage stability analysis to the master although the proposals by Norway have helped greatly in clarifying the issues involved and providing a basis for discussion. In an attempt to try to see more clearly what we are trying to achieve by integrating all the limiting GM/KG curves for intact and damage stability into something understandable for the crew, we have drawn up a table (below) summarizing all the criteria with the appropriate draughts and trims relevant to a passenger ship. It can be clearly seen from the table that in integrating intact and damage stability critical curves we are attempting to combine data from deterministic and probabilistic sources and it may be this that is causing us some difficulty as the two do not really mix very well. For example, when we calculate A to ensure that A>=R, this is not really a stability characteristic comparable, say, with the area under the residual GZ curve. It is really a “spot check” on the overall safety level of this ship in comparison with the safety level of a large fleet of similar vessels. The regulations as they stand require this “spot check” to be carried out at 2 specified draughts at level trim and a light draught at the corresponding service trim. The KG or GM used in these calculations may not necessarily be “critical” such that A=R; in some cases A could be much greater than R, in which case no critical GM/KG can be said to exist for that “criterion” as the choice of input KG/GM can be almost random.

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With respect to trim, the regulations currently imply that compliance with A>=R using level trim for ds and dp and service trim for dl can then be assumed across a trim range from +0.5%L to 0.5%L. Only if the operating trim exceeds these limits are further A>=R calculations needed, to ensure that there is no major reduction in safety at operating trims in excess of +/-0.5%L. But this is again a “spot check” and does not readily lend itself to the production of valid GM/KG limit curves interpolated between level trim and the extremes of the operating trim as the choice of input GM/KG can be fairly arbitrary and it is quite possible for A to be much greater than R. In a similar way, the additional requirement in Reg. 6.1 that the partial indices As, Ap and Al are each greater than or equal to 0.9R for pax ships and 0.5R for cargo ships is designed to ensure that there is a significant contribution to A at each of the 3 load draughts, which used to be a problem in SOLAS90 Reg.25 for cargo ships where nearly all the contribution to A could come from the light draught. Again, this is a “spot check” to overcome a specific problem, and is therefore not really amenable to the production of “critical” GM/KG curves interpolated across a range of trims. The regulations within SOLAS2009 which are more amenable to producing meaningful critical KG/GM curves are those requiring “si” to be a certain value (Reg. 8.1, 8.2 and 9.8) although only Reg. 9.8 is stated to be applicable “for all service conditions”. As Denmark suggests, the critical situation for compliance with Reg. 8.1 is likely to be at ds with maximum operational bow trim, whereas for Reg. 8.2 and 9.8 the operational range of trims and draughts should be covered. The above begins to suggest a procedure for the designer to develop useful limiting curves:1. First calculate the intact stability limiting GM/KG curves in accordance with 2008 IS Code covering criteria I1 to I8 in the table below at suitable draught and trim increments across the operational ranges. 2. For the same draughts and trims calculate damage criteria for Reg. 8.1, 8.2 & 9.8. 3. Plot minimax critical GM/KG curves across the operational range of draught and trim for the intact and damage criteria in 1 and 2 only. 4. Using the critical KG/GM’s from these calculations, at the appropriate trim(s) and ds, dp and dl ensure that A>=R and that the partial indices in Reg. 6.1 are all compliant. 5. If the operational trim range exceeds +/- 0.5%L carry out further spot checks on A>=R and the partial indices using the appropriate critical GM/KG’s derived from 1 and 2 but do not attempt to plot any critical curves based on the “criteria” in Reg. 6.1. 6. Add a statement in the Stability Booklet to say that “Provided the ship is loaded in accordance with the limiting GM/KG curves/tables, the minimum A/R ratio for damage stability will be 1.xxx and the partial indices at ds, dp and dl will be always >= 0.9R (>=0.5R for cargo ships)”. If the above procedure is agreed to in principle, we could either try to provide appropriate revisions to the Regulations and EN in time for Round 3 or use a drafting group at SLF 53.

Appendix 1 Q1. Do you agree in principle with the procedure outlined above for providing integrated limiting GM/KG curves to the crew whilst verifying that the probabilistic elements of S2009 Reg. 6 and 7 are complied with?

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Yes

MI, Japan, Norway, CLIA (Agree in part – see comments), UK, Denmark

No

Germany (with comments), Finland (with comments), Italy (with comments)

Comments?:MI: Yes, agree in principle with the procedure. Germany: 1) Also for reg 8 and 9 the same initial conditions as for reg 6 (dl, dp, ds) should be used resulting in one GM limit curve for all damage aspects. Trim range of 0.5%Ls should be used for all 3 draughts. 2) The procedure from the coordinator to obtain GM/KG limit curve is technically meaningful for designers, but this does not solve the problem in application of correct limiting curves covering the relevant parameters draft, trim, GM. Germany understands the damage stability calculation as a “design parameter” that shows the capabilities of a vessel and ensures the required safety level. Having this in mind the following principles should be incorporated to the EN 1. DRAFT Î as close as possible” in alignment with the load case “Ballast Arrival” (this ensures that the entire operation scope of the vessel is covered by the limit curve) 2. TRIM Î trim is a “design parameter” and can freely chosen by the designer (*** see below remark) 3. GM Î GM is a “design parameter” and can freely chosen by the designer (*** see below remark) Important remark *** for all load cases Î it is to be ensured that ALL load cases (incl. “Ballast Departure”) are within the limitation (trim, GM) from the damage stability calculation. This could also mean that additional damage stability calculations with different trim level are to be carried out by the designer We appreciate the proposal by Norway and related technical comments as a good approach to give a general guidance. However, several details need to be clarified such as - clarity of diagrams related to trim restriction for “easy on-board use - application of +/- 0.5%L trim range also for the light service draft DL, etc). Further we are concerned that for certain scenarios inappropriate restrictions to designers could occur. Therefore we regard any such proposal as an additional part of the EN only, but such guidance should not be tailored as a compulsory schema. Therefore we regard the methodology of the “GM envelope curve” as the paramount principle. Finland: For all 3 draughts trim range of 0.5 %Ls should be applied. Italy: The procedure outlined above is not acceptable. In particular on item 2 the damage assessments for Reg. 8.1, 8.2 & 9.8 were never intended to be carried out with all drafts and trims of intact stability. Moreover on item 4, if A< R it is not clear what should be done. For these reasons ITALY fully supports the proposal made by CLIA/CSSF, here attached for easy reference :

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“This issue and the EN is handled in the CSSF work:The calculation of different trims as proposed by Norway (SLF52/17/4) is shown below in a slightly simplified way and supported by the group. The concept of fixed trim at the light service draught has been removed and the normal trim range of 0.5% Ls is also applied here. However more examples might be useful in the final EN to illustrate the concept, in particular for trim variations at draughts between dl and dp. “3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7 an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations 4 As an alternative to an envelope curve the calculations for additional trims may be carried out with one common GM for all of the trims assumed at the deepest subdivision draught ds and the partial subdivision draught dp respectively. The lowest values of each partial index As and Ap across trims will then be used in the summation of attained subdivision index A according to regulation 7 5 It is not required that the trim values at ds, dp and dl coincide as long as the limitations with respect to variation between trims are observed at each draught.” France: Outlined procedure is a possible option but may not be the only one. It should always be possible to study independently intact and damage stability criteria and to combine them in final. One of the problems is that usually much more draft/trim conditions are studied for intact stability criteria than for damage stability criteria. In addition, for some ships, two sets of intact stability curves are presented depending on encountered weather conditions. In the same way, two set of damage stability curves may be provided if several subdivision load lines are assigned. Anyway this principle can help us in the process to define integrated limiting GM/KG curves. CLIA: In our experience, for Cruise Vessels the following is the procedure used in reality and the limit diagrams produced: 1) Calculate the Intact limiting GM/ KG values for a range of draughts at a range of trims. Present them as GM or KG limit curves with an X axis of draught, with a curve for each trim. 2) Calculate limiting GM/ KG values for regulation 6-7 (including partial A indices requirements) for A=R, at dl, dp, ds, then check at the limiting GM values for each of the three conditions, that compliance with regulations 8 and 9 is achieved. Present them as GM or KG limit curves on the same axes as intact limits. 3) If trim is more than 0.5%Ls, then there will need to be Reg 6-7 A=R GM or KG limit curves for each trim (although not normally the case for cruise ships). 4) For a ship where compliance with Reg 8 or 9 is NOT achieved at the Reg 6-7 limiting GM values, then calculate the limiting GM/ KG curve for compliance with Reg 8 (or 9) at the same 3 draughts. At that limit curve, A will be >R and this can be stated on the diagram/ manual.

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5) For each of the trims from the Intact limits (it’s assumed that if needed, trims chosen for damage stability would coincide), overall “envelope” limits for GM or KG for both intact and damage requirements can be drawn, with X axis of draught, making a very simple presentation for the master, equivalent to the limit diagrams from the SOLAS 90 rules.

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Criteria to be complied with 2008 IS CODE INTACT STABILITY Regulation 2.2.1 Area under GZ curve not to be less than 0.055 m-rads up to 30 degrees 2.2.1 Area under GZ curve not to be less than 0.09 m-rads up to 40 deg or downflooding 2.2.1 Area under GZ curve not to be less than 0.03 m-rads between 30 to 40 deg (or d'flood) 2.2.2 GZ shall be at least 0.2 m at an angle of heel equal to or greater than 30 degrees 2.2.3 The maximum righting lever shall occur at an angle of heel not less than 25 degrees 2.3 Severe wind and rolling criterion - area b>=area a 3.1.1 Angle of heel due to passenger crowding not to exceed 10 degrees 3.1.2 Angle of heel due to turning not to exceed 10 degrees S2009 DAMAGE STABILITY Regulation 6.1 Attained Index A not to be less than Required Index R The draughts and trims to be used in calculating A are specified in Reg. 7.2:"In the calculation of A, the level trim shall be used for dl and dp. The actual service trim shall be used for dl. If, in any service condition, the trim variation in comparision with the calculated trim is > 0.5%Ls, one or more additional calculations of A are to be submitted for the same draughts but diffeent trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5%Ls."

Code

Trims?

Draughts?

I1 I2 I3 I4 I5 I6 I7 I8

Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range

Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range Operating Range

D1

D1a

Actual Service dl Level if trim < 0.5%Ls dp Level if trim < 0.5%Ls ds If trim >=0.5%Ls, A to be calculated again at trim = 0.5%Ls & so on until the difference between the actual and reference trim does not exceed 0.5%Ls (dp & ds only)

6.1

Partial indices As, Ap and Al are to be each individually >= 0.9R (0.5R for cargo ships)

D2 D3 D4

As for A? As for A? As for A?

dl dp ds

8.1

si = 1 for damage to all compartments within 0.08L from the FP (>= 400 pax)

D5 D6 D7

As for A? As for A? As for A?

dl dp ds

8.2

si = 0.9 for minor side damages with penetration depth varying with pax numbers

D8 D9 D10

As for A? As for A? As for A?

dl dp ds

9.8

si = 1 when subject to specified bottom damage

D11

All service

All service

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APPENDIX 2 [Coordinator’s Note: For information, the current regulations in the SOLAS2009 Consolidated Edition covering Regulation 5-1 (Stability Information to be supplied to the master) and Regulation 7 (the attained subdivision index, A) and the explanatory notes are shown without comments for easier comparison with the proposed changes in Appendix 1.] Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) versus draught which assures compliance with the relevant intact and damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact and stability after damage.

Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information.

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456); Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706); and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls. 4 For ships which have to fulfil the stability requirements of part B-1, information referred to in paragraph 2 is determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way. 5 When curves or tables of minimum operational metacentric height (GM) versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated.

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Regulation 7 Attained subdivision index A 1 The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted.

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2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1 2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below.

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs.

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2 In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of Ls, one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. Regulation 7.2 1. The calculations for differing trim should be carried out with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. 3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

3 When determining the positive righting lever (GZ) of the residual stability curve, the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used.

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4 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 5 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only to the centreline and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads. 6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. 7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired.

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Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total cross-sectional area of not more than 2

710 mm between any two watertight compartments.

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APPENDIX 3 [Coordinator’s Note: For information, the current regulations in the SOLAS2009 Consolidated Edition covering Regulation 5-1 (Stability Information to be supplied to the master) and Regulation 7 (the attained subdivision index, A) and the explanatory notes are shown amended in accordance with the method outlined under the discussion at the end of Appendix 1 (Ref. Appendix 1 Q1, above.] Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) versus draught which assures compliance with the relevant intact [stability requirements of part A of the 2008 IS Code] and [relevant] damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact [stability according to the requirements of part A of the 2008 IS Code] and stability after damage.

[Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information.]

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456)[; Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706)] and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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3 The [intact and damage] stability information [required by regulation 2.1] shall [encompass the operating range of draught and trim.]. [shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls.] 4 For ships which have to fulfil the stability requirements of part[s] B-1 [and B-2, the limiting GM/KG] information referred to in regulation[s] 2[.1] [and 3] is determined from considerations [of the appropriate intact stability criteria in combination with the damage stability criteria in regulations 8.1, 8.2 and 9.8. No limiting GM/KG curves/tables are to be calculated for demonstrating compliance with the criteria in regulations 6.1 and 6.2. Instead a note is to be added to the stability information provided to the master stating the achieved A/R ratio and partial indices at level trim and also at the extremities of the trim ranges forward and/or aft but only if these exceed +/-[0.2][0.5]% of L at any of the three draughts specified in regulation 7.1.]

related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) Linear interpolation of the limiting values between the draughts ds, dp and dl is 1. only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated.

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[1. The combined intact and damage limiting GM/KG curves/tables may be produced as follows:.1 Calculate the limiting GM/KG curves/tables for the appropriate intact stability criteria at suitable draught and trim increments across the operational range. .2 For the same draughts and trims calculate the limiting GM/KG curves/tables for the damage stability criteria in regulations 8.1, 8.2 and 9.8. .3 Combine all the results to determine the most onerous criteria across the trim range at specified draughts and produce limiting curves or tables of GM/KG for use by the master. .4 For the three draughts specified in Regulation 7.1 select, at level trim, the most onerous values of GM or KG at each draught (by linear interpolation if necessary) and use these values to calculate the attained subdivision index, A and the partial indices As, Ap and Al to demonstrate compliance with Regulation 6.1. .5 If the operating trim range exceeds +/- [0.2][0.5]% of L at any of the 3 draughts specified in Regulation 7.1, then repeat the calculation of A and the partial indices at the extremities of the trim range forward and/or aft using the appropriate limiting GM/KG for each draught / trim (by linear interpolation if necessary) to ensure compliance with Regulation 6.1. 2. If it is found that the attained index or partial indices do not meet the criteria in Regulation 6.1 then the subdivision arrangements must be improved and the procedure repeated until compliance is achieved. Compliance with Regulations 6.1 and 6.2 may not be achieved by increasing the GM (lowering the KG). 3. In addition to the curves/tables of limiting GM/KG the statement below should be added to the stability information booklet giving the calculated values of the A/R and the partial indices ratios to demonstrate compliance with Regulations 6.1and 6.2:“Provided the ship is loaded in accordance with the limiting GM/KG curves/tables, the ratio of attained / required index (A/R) at level trim for damage stability will be 1.xxx (minimum 1.000). At maximum operational bow trim the A/R ratio increases/decreases to 1.yyy and at maximum operational stern trim the A/R ratio increases/decreases to 1.zzz. At level trim the partial indices As, Ap and Al are x.xxxR, x.xxxR and x.xxxR respectively (minimum 0.9R or 0.5R, as appropriate) changing to x.xxxR, x.xxxR and x.xxxR at maximum operational bow trim and x.xxxR, x.xxxR and x.xxxR at maximum operational stern trim”.] 5 When curves or tables of minimum operational metacentric height (GM) [or maximum operational (KG)] versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the [intact and damage] stability criteria are satisfied for this loading condition.

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Regulation 7 Attained subdivision index A 1 The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted.

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2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1 2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG) [(refer to the Explanatory Notes for regulations 5-1.3 and 5-1.4 for determination of the GM (or KG) to be used)]. The mean draught and trim are illustrated in the figure below.

The GM (or KG) values for the three loading conditions could, as a first attempt, 6. be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact

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loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. 2 In the calculation of A, [the] level trim shall be used for the [deepest subdivision] [three] draught[s specified in regulation 7.1.] [and the partial subdivision draught. The actual service trim shall be used for the light service draught]. If [, at any of the three draughts,] [in any service condition], the [maximum operational] trim [variation in comparison with the calculated trim is greater than] [exceeds +/-] [0.2][0.5]% of [Ls ][L], [one or more additional] [further] calculations of A are to be submitted for the same [three] draughts [at the maximum operational trim forward and/or aft specific to each draught.] [but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls.]. [Note: A clean version of the above paragraph is given below for ease of reference:-] 2 In the calculation of A, level trim shall be used for the three draughts specified in regulation 7.1. If, at any of the three draughts, the maximum operational trim exceeds +/[0.2][0.5]% of L, further calculations of A are to be submitted for the same three draughts at the maximum operational trim forward and/or aft specific to each draught. Regulation 7.2 1. The calculations for differing trim should be carried out [as described in the Explanatory Notes for Regulations 5-1.3 and 5-1.4.] with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. 3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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3 When determining the positive righting lever (GZ) of the residual stability curve, the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. 4 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 5 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only to the centreline and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the

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methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads. 6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. 7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a total cross-sectional area of not more than 2

710 mm between any two watertight compartments.

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APPENDIX 4 •

THIS APPENDIX CONTAINS THE ROUND 5 DISCUSSION ON REGULATIONS 5-1 and 7 AND THE ACCOMPANYING QUESTIONNAIRE, WITH RESPONSES.

•

IT CONSISTS OF THREE MAIN SECTIONS AS EXPLAINED AND IS COLOUR-CODED.

•

IT SUPERSEDES APPENDICES 1 to 3, ABOVE WHICH ARE RETAINED FOR REFERENCE ONLY.

•

PLEASE NOTE THAT THE SECOND SECTION CONTAINS NORWAY’S PROPOSALS PRIOR TO SLF 53.

•

THESE WERE THEMSELVES SUPERSEDED BY NEW PROPOSALS FROM NORWAY WHICH CAN BE FOUND IN THE ROUND 6 SUPPLEMENTARY DISCUSSION PAPER AND QUESTIONNAIRE IN APPENDIX 5.

•

AT SLF 54 IT IS PROPOSED TO CONCENTRATE ON THE LATEST PROPOSALS FROM NORWAY IN APPENDIX 5 WHICH THE MEMBERS GENERALLY PREFERRED TO THE ALTERNATIVE FROM THE UK IN APPENDIX 3.

•

SOME ISSUES WILL NEED TO BE RESOLVED BY DISCUSSION AT SLF 54.

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SOLAS Consolidated Edition 2009 with

Explanatory Notes (Res. MSC.281(85)) Applicable to Passenger and Cargo Ships with keels laid on or after 1st January, 2009 KEY TO COLOUR CODES and FONTS USED IN THIS DOCUMENT SOLAS Consolidated Edition 2009;

Current SOLAS text

Resolution MSC.281(85);

Current Explanatory Notes (EN)

Agreed Regulatory Text Changes

Changes to SOLAS agreed up to Round 4

Agreed EN Text Changes

Changes to EN text agreed up to Round 4

Q21

Reference to question in working document

SOLAS Consolidated Edition 2009;

Regulation text still under discussion

Resolution MSC.281(85);

EN text still under discussion

This document contains Round 5 of the 2011 SDS CG questionnaire covering the following regulations and explanatory notes only:Regulation 5-1 ...................................................Stability Information to be Supplied to the Master Regulation 7 …....................................................................................Attained Subdivision Index A 1) Comprises the 2009 Consolidated Edition text and EN with text changes etc. as agreed at SLF 53 in January 2011 using the above colour codes followed by a discussion of the main problems found to date with the above regulations and EN’s. 2) Consists of a series of amendments in blue proposed by Norway prior to SLF 53. 3) An alternative series of amendments in blue proposed by the UK / Co-ordinators. There is a question at the end of each of the three sections for comments, additional items that may have been overlooked or alternative proposals. Please refer to the working document for full background information, including previous questions, discussions and responses.

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1)

2009 Consolidated Text & EN with SLF 53 agreed amendments

Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) [and maximum permissible trim] Q18 versus draught which assures compliance with the relevant intact [stability requirements of part A of the 2008 IS Code] and [relevant] Q19 – proposed inserts not accepted damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability [according to the requirements of part A of the 2008 IS Code] Q19 – proposed inserts not accepted and stability after damage.

Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information. 3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls 3 The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board. Q20

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456) [; Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706)] Q6; and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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2009 Consolidated Text & EN with SLF 53 agreed amendments

4 For ships which have to fulfil the stability requirements of part B-1, information referred to in paragraph 2 is determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated. Q21 – to be considered in Round 5 5 When curves or tables of minimum operational metacentric height (GM) versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition.

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1)

2009 Consolidated Text & EN with SLF 53 agreed amendments

Regulation 7 Attained subdivision index A 1 The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Q22 – to be considered in Round 5 A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1

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19th September, 2011

1)

2009 Consolidated Text & EN with SLF 53 agreed amendments

2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below.

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. Q23 and Q24 – to be considered in Round 5 2 In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of Ls, one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls.

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2009 Consolidated Text & EN with SLF 53 agreed amendments

Regulation 7.2 1. The calculations for differing trim should be carried out with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. 3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

Q25 and Q26 – to be considered in Round 5 3 When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding Q27(2) and see Reg. 7.6 , the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. Regulation 7.3 “The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be

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1)

2009 Consolidated Text & EN with SLF 53 agreed amendments

assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.” Q27(3) 4 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 5 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only [to the centreline] to one half of the ship breadth B CLIA Q2 and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. 3. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads. 6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed [in the final stage of flooding]. Q27(2) and see Reg. 7.3. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed.

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2009 Consolidated Text & EN with SLF 53 agreed amendments

7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck. CLIA Q3 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than 2

[710 mm ] [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all [this] [these] small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]]. CLIA Q4 Why do we need to consider changes to regulations 5-1 and 7 covering stability information to be supplied to the master? New Discussion for Round 5 of CG. Some of the main reasons why changes have been proposed by Norway and the UK to the above regulations and EN summarized from discussions in earlier rounds of the CG are given below:1) Difficulties with integrating KG/GM limit curves for intact and damage criteria 1.1 There are real difficulties in providing the draught/trim/limiting GM/KG curves in a form easily usable on board especially in consolidating all the applicable intact and damage criteria across the operating range of draughts and trims into simple graphs or tables for use by the master. For example there was no requirement in S2009 for a vessel with an operating trim range of < +/- 0.5%L to be provided with anything other than level trim damage critical GM/KG information (see Reg. 7.2). A problem then arises where, according to the 2008 IS Code applied, for example, to a ship with L = 200 m. having an operating draught range of 4.0 to 5.8 m. and trim range just below +/- 0.5%L (= 1 m.) the critical KG information could be presented as shown in Fig. 1 below. Note that each point on the intact stability curves is the lowest of the complete set of applicable intact stability criteria. It is only possible to plot three points from the damage stability criteria - at draughts dl=4.15m (assumed service trim = 0.75 m by stern), dp=5.14m and ds=5.8m (at level trim only) making interpolation of a specific critical KG for a given draught at non-zero trim impossible. The same applies to the next figure (fig. 2) showing critical KG against draught. It is also not clearly stated in the Reg. 7.2 or EN whether the variation of critical KG/GM with trim applies only to the A>R criterion in Reg. 6.1 or also to:a) partial indices criteria >0.9R (0.5R for cargo ships) in Reg. 6.1 b) fore end damage criteria in Reg. 8.1 c) minor side damage criteria in Reg. 8.2 d) bottom damage criteria in Reg. 9.8 (which are to be calculated for all draughts and trims). For this exercise it is assumed that the damage critical KG’s shown in the figures below are the minima from all the above damage criteria.

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2009 Consolidated Text & EN with SLF 53 agreed amendments

Max Allowable Intact + Damage KG vs Trim dr = 4.0

dr = 4.2

dr = 4.4

dr = 4.6

dr = 4.8

dr = 5

dr = 5.2

dr = 5.4

dr = 5.6

dr = 5.8

dl = 4.15

dp=5.14

ds = 5.8

10.50

10.00

Crit KG (m.)

1)

9.50

9.00

8.50

8.00 -1

-0.5

0

0.5

1

Trim (m.) Fig. 1 Trim vs Critical KG’s (intact and damage) at specified draughts with Trim Range < 0.5%L

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2009 Consolidated Text & EN with SLF 53 agreed amendments

Fig. 2 Max. Allowable Intact + Damage KG vs Draught Trim = -1

Trim = 0

Trim = 1

Damage Trim -0.75

Damage Trim = 0

Damage Trim = 0

10.50

Critical KG (m.)

10.00

9.50

9.00

8.50

8.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

Fig. 2 Draught vs Critical KG curves (intact and damage) at specified trims with Trim Range < 0.5%L 1.2 It can be seen from the above that interpolation to determine the damage/intact critical KG for any other than the 3 damage draught/trim combinations shown by the spots is not possible. If the operating trim range in the above example ship was, say, 2.0 m. by the stern and 2.0 m. by the bow, then according to regulations 5-1.3 (before the alterations agreed at SLF 53) and 7.2, further critical KG calculations are required such that the “difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls.” These extra calculations now make interpolation between trims possible but there are still some uncertainties (see Fig. 3 and Fig.4 below).

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2009 Consolidated Text & EN with SLF 53 agreed amendments

Fig. 3 Max Allowable Intact + Damage KG vs Trim dr = 4.0

dr = 4.2

dr = 4.4

dr = 4.6

dr = 4.8

dr = 5

dr = 5.2

dr = 5.4

dr = 5.6

dr = 5.8

dl = 4.15

dp = 5.14

ds = 5.8

10.50

10.00

Crit KG (m.)

9.50

9.00

8.50

8.00 -2

-1.5

-1

-0.5

0

0.5

1

1.5

2

Trim (m.)

Fig. 3 Trim vs Critical KG curves (intact and damage) at specified draughts with Trim Range > 0.5%L 1.3 It can be seen that this combined diagram as it stands cannot easily be used for interpolating between intact and damage critical KG’s at specific intermediate draughts and trims. Only by separating the intact and damage curves, interpolating KG for draught and trim for each and then finding the minimum value could any answers be obtained. It would make it easier if the intact criticals could also be calculated at ds, dp and dl. Even so interpolation between dp and dl to find the damage critical KG is not possible as only the service trim is calculated for dl.

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2009 Consolidated Text & EN with SLF 53 agreed amendments

Fig. 4 Max. Allowable Intact + Damage KG vs Draught Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

Damage Trim -2

Damage Trim -1

Damage Trim -0.75

Damage Trim 0

Damage Trim 1

Damage Trim 2

10.50

Critical KG (m.)

10.00

9.50

9.00

8.50

8.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

Fig. 4 Draught vs Critical KG curves (intact and damage) at specified trims with Trim Range > 0.5%L 1.4 Although this diagram is easier to interpret than fig. 3 there is a gap in the damage critical KG curves between dl (4.15 m.) and dp (5.14 m). The current explanatory notes for Reg. 5-1.3 and 5-1.4 are based on linear interpolation between dl, dp and ds but only for limiting GM lines so interpolation using the above KG diagram would not be valid. Under the existing regulations the “gap” between dl an dp must be closed by linear interpolation on limiting GM (as shown in fig. 7 below). The limiting GM curves derived from the above are shown in fig. 6. The assumed KM curves used to convert KG to GM using GM = KM – KG are shown in fig. 5 below for information.

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Fig. 5 KM against Draught for various trims Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

15.00

14.00

KM m.

13.00

12.00

11.00

10.00 4.00

4.50

5.00

5.50

6.00

Draught m.

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Fig. 6 Min. Required Intact + Damage GM vs Draught Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

Damage Trim -2

Damage Trim -1

Damage Trim -0.75

Damage Trim 0

Damage Trim 1

Damage Trim 2

6.00 5.50 5.00 4.50

Minimum GM (m.)

4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

Fig. 6 Draught vs Limiting GM curves (intact and damage) at specified trims with Trim Range > 0.5%L 1.5 The maximum allowable KG curves in fig. 4 have been converted to minimum required GM curves using GM = KM (from fig. 5) – KG. Fig. 7 below shows how the linear extrapolation between dp and dl is carried out in accordance with the current EN for Reg. 7.1 and 7.2.

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Fig. 7 Min. Required Intact + Damage GM vs Draught Showing Linear Extrapolation between dp and dl Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

Damage Trim -2

Damage Trim -1

Damage Trim -0.75

Damage Trim 0

Damage Trim 1

Damage Trim 2

6.00 5.50 5.00 4.50

Minimum GM (m.)

4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

Fig. 7 Draught vs Limiting GM curves (intact and damage) at specified trims with Trim Range > 0.5%L showing linear extrapolation converging to a single value at dl 1.6 How would the Master use the above curves to calculate minimum GM at a specified draught and trim? It can easily be seen that for draughts > approximately 4.72 metres the damage stability limiting GM curves are more onerous than the intact. So if the actual draught is, for example, 5.5 metres and the trim is 1.2 metres by the stern the minimum GM by interpolation is approximately 3.15 metres. At draughts less than 4.72 metres (for example 4.5 metres and trim of -1.2 metres), the intact and damage minimum GM’s would be read off separately with the largest value being the overall critical GM – e.g. damage 3.83 m. intact 3.98 m so critical GM is 3.98 m. According to EN3 for Reg. 7.2 Fig. 7 can be simplified by using an envelope curve:-

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Fig. 8 Min. Required Intact + Damage GM vs Draught Showing Envelope Curve Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

Damage Trim -2

Damage Trim -1

Damage Trim -0.75

Damage Trim 0

Damage Trim 1

Damage Trim 2

6.00 5.50 5.00 4.50

Minimum GM (m.)

4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

Fig. 8 Draught vs Limiting GM curves (intact and damage) at specified trims with Trim Range > 0.5%L showing an envelope curve covering all trims 1.7 Using the above example, the minimum GM for draught 4.5 metres at any trim is 4.05 m. It should be noted that:• the current EN’s only show an envelope curve for damage stability limiting GM data. • the EN method will provide a safety margin whenever the actual trim lies within the extreme limits. • for passenger ships, where the trim range is usually quite small, this method may be satisfactory but for ro-pax or cargo ships the master may legitimately prefer to use the correct trim curves rather than the envelope, especially if compliance is marginal.

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We are slightly puzzled as to why the critical KG curves show that that the bow trim curves (+2 metres) for intact and damage stability in fig. 4 are the most onerous whereas for the limiting GM curves in fig. 8 the stern trim curves (-2 metres) are more onerous. Of course, we are not using data from an actual ship so that there may be inconsistencies but we wonder whether this may point to the fact that with limiting GM curves another variable has been introduced which varies with trim (i.e. KM). Limiting KG and limiting GM may not therefore be equivalent. This is discussed in more detail below.

2) Are Critical KG Curves and Limiting GM Curves Equivalent? 2.1 The regulations and EN’s would suggest that limiting KG and GM curves are interchangeable and equivalent but the previous calculations (expanded below) appear to indicate otherwise. Beginning with the GM limiting envelope curve (heavy red line in fig. 8) and following the guidance in Reg. 5-1.3 and 5-1.4 EN1:1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught We obtained:Fig. 9 Converting GM envelope to KG envelope curve using KM interpolation method in EN1 for Reg. 5-1.3 Draught 4.00 4.15 4.20 4.40 4.60 4.80 5.00 5.14 5.20 5.40 5.60 5.80

GM env 5.65 5.00 4.79 4.29 3.90 3.80 3.71 3.65 3.59 3.35 3.11 2.90

at Trim? Intact -2 Intact -2 Intact -2 Intact -2 Linear Int* Linear Int* Linear Int* Damage -2 Damage -2 Damage -2 Damage -2 Damage -2

KM at trim

14.50 14.20 14.10 13.90 13.29 13.21 13.14 13.10 13.02 12.70 12.10 11.40

KG env 8.85 9.20 9.31 9.61 9.39 9.41 9.43 9.45 9.43 9.35 8.99 8.50

* Trim obtained by linear interpolation between damage at trim -2 and draught 5.14 and damage at trim -0.75 and draught 4.15 metres:Draught 4.15 4.60 4.80 5.00 5.14

Trim -0.75 -1.32 -1.57 -1.82 -2.00

KM see fig 5

13.97 13.29 13.21 13.14 13.10

The resulting KG envelope curve is shown below (fig. 10):-

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Fig. 10 Max. Allowable Intact + Damage KG vs Draught (Fig. 4 with added KG Envelope Curve derived from GM envelope) Trim = -2

Trim = -1

Trim = 0

Trim = 1

Trim = 2

Damage Trim -2

Damage Trim -1

Damage Trim -0.75

Damage Trim 0

Damage Trim 1

Damage Trim 2

From GM envelope

10.50

Critical KG (m.)

10.00

9.50

9.00

8.50

8.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

2.2 It can be seen that in this case the KG envelope curve is easier to comply with than the lines plotted for each individual trim (in the regions where these can be directly compared). This contrasts with the limiting GM envelope curve which had an increased safety margin compared to the individual trim lines. The above KG envelope curve appears to give optimistic results for critical KG, eg draught 5.5 m. - envelope curve limit is 9.2 m. - level trim limit only 8.8 m. 2.3 Again, we think this may be due to the fact that KM varies with trim at a given draught but it seems to confirm that limiting GM and limiting KG curves may not be equivalent. The problem is made worse where the trim range is less than 0.5%L and only level trim limiting GM/KG curves are calculated for dp and ds. As France stated in an earlier CG discussion:“If constant GM or KG is kept for a trim range, presentation in max KG is more favourable for trim by bow and presentation in GM is more favourable for trim by stern. Up to 0.20m difference may be observed - so limit of 0.5% of Ls may be questioned”.

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3) Choice of initial KG/GM to calculate A – influence on critical KG/GM 3.1 EN5 and 6 for Reg. 7.1 state:5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below.

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. 3.2 The first point to note with EN’s 5 and 6 is that they only relate to obtaining the required index R at level trim for dp and ds and at the service trim for dl (Reg. 7.2 deals with trim >0.5%L). The procedure for calculating the combined damage/intact GM/KG limit curve in cases where the trim range is =R go to b) b) For Reg. 6.1 calculate Al, Ap and As. If each >= 0.9R (0.5R for cargo ships) go to c) c) For Reg. 8.1 calculate s for each of the 3 draughts for a damage involving all compartments lying within 0.08L aft of the FP. If s = 1 for each draught go to d) d) For Reg. 8.2 calculate s for each of the 3 draughts for minor damages in Reg. 8.3. If s >=0.9 for each draught go to e) e) For Reg. 9.8 calculate s for “all service conditions” when subject to specified bottom damages. If s = 1 (presumably for all draughts in the range specified for the intact stability calculation at level trim and for dl at the service trim) then the calculation for level trim is finished 3.4 If, at any of the above steps, a criterion is not met then the KG is decreased (GM increased) and the calculation repeated until compliance is achieved for all the damage criteria. This implies that the damage stability limit curve is more onerous than the intact, as explained in EN 6 for Reg. 7.1. If the KG has to be lowered (GM increased) at step b) to e) to achieve compliance, then A will increase as will one or more of the partial indices in step b). It is not clear as to whether step a) and b) should then be repeated using the new lowest KG(s) (highest GM(s)) and the improved “A” and partial indices noted somewhere. This could be clarified in the EN.

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Fig. 11 Starting point - Calculate A using Intact Critical KG's at each draught Trim = -1

Trim = 0

Trim = 1

dl Damage Trim -0.75

dp Damage Trim = 0

ds Damage Trim = 0

10.50

Critical KG (m.)

10.00

9.50

9.00

8.50

8.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

3.5 If, at step a) or b), the damage stability criteria for A or the partial indices are not met then the KG must be lowered (GM raised) at one or more of the three draughts dl, dp or ds. Here there is a slight ambiguity. “dl” may be at a different trim from dp and ds – the “actual service trim” which is always fixed. Is the KG/GM for dl also fixed or can it be lowered/raised along with the KG/GM for dp and ds to increase “A” and/or the partial indices? This is not made clear in the regulations or EN. Technically, changing the KG/GM would have a small influence on trim therefore there is a case for saying that trim and KG/GM for dl must be fixed throughout. There is another slight ambiguity here. We have shown in fig. 11 above the KG for dl corresponding to the limiting intact stability KG as suggested in Reg. 7.1 EN6. But what if the KG for the actual light service draught dl is less than the intact critical KG? Must that fixed KG from an actual loading condition be used throughout the damage calculations? Again this is not clear from the regulations or EN.

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3.6 Shown below in fig. 12 is one method of increasing A to meet R in step a) if it is found that AR in the first iteration of step a) meaning that there would not necessarily be a critical KG/GM value for A=R. Also, perhaps not all software packages are capable of iterating to a solution for A=R. In this case “A”/ “R” simply becomes a number and the limiting KG/GM curves are determined by the intact or other damage stability criteria.

Fig. 12 Increasing "A" so that A=R by lowering KG at dp Trim = -1

Trim = 0

Trim = 1

dl Damage Trim -0.75

dp Damage Trim = 0

ds Damage Trim = 0

10.50

Critical KG (m.)

10.00

9.50

9.00

8.50

8.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

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3.7 If shifting the KG for dp as shown in fig. 12 results in A=R and all the remaining damage criteria in steps a) to e) above are satisfied then the above graph must be converted to show minimum GM rather than maximum KG to allow for linear interpolation for intermediate draughts (see fig. 13 below). Fig. 13 Increasing "A" so that A=R by increasing GM at dp Minimum Required GM Trim = -1

Trim = 0

Trim = 1

dl Damage Trim -0.75

dp Damage Trim = 0

ds Damage Trim = 0

6.00 5.50 5.00 4.50

Minimum GM (m.)

4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 4.00

4.50

5.00

5.50

6.00

Draught (m.)

3.8 Apart from the anomaly mentioned earlier that for the minimum GM intact curves stern trim is more onerous whereas for the maximum allowable KG curves head trim is more onerous a question arises about what to do if the ship is operating at a non-zero trim, bearing in mind that if the trim range is within + / - 0.5%L there is no requirement to calculate trimmed damage curves. CLIA mentions that passenger vessels often operate within these narrower trim limits. In the above example, if the ship is sailing at a draught of 5.7 metres with a stern trim of 0.9 metres how does one interpolate between the level trim damage curve and the intact curves at -0.9 metres trim? The situation is even more confusing if the draught is less than dp as the trim for the

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damage critical GM line varies between zero trim at dp and -0.75 metres trim at dl. From fig. 13, how does one interpolate the correct limiting GM for a draught of say 4.5 metres with a stern trim of 0.9 metres, for example? 3.9 Also, if the full S2009 damage calculations were to be carried out specifically at a draught of 5.7 m. and trim -0.9 m. then the minimum allowable GM to comply with all the damage criteria may be, for example, 2.5 metres. In fig. 13, the red damage GM line linearly interpolated at 5.7 metres is only 1.1 metres so there is the potential for a considerable error. If the actual GM for the loading condition lies on the red limit line above at 5.7 metres draught (1.1 m.) the ship would appear to comply with S2009 whereas in reality she could have a GM deficit of up to (2.5 – 1.1 = 1.4 m). All these numbers are hypothetical but it is hoped that the point is made. 3.10 The situation improves somewhat if the operating trim exceeds + / - 0.5%L as further trimmed damage critical GM limit curves are produced at, say, + / - 0.5% L and + / - 1.0% L. There remain presentational problems in integrating the intact and damage limit curves and on interpolating for the actual draught and trim. 4) SUMMARY 4.1 Norway and the UK tried to address some of the issues raised in the above discussion and their proposed amendments are shown in Sections 2 and 3, below. 4.2 Some changes to regulations 5-1 affecting information to the Master have already been agreed at SLF 53 as highlighted at the beginning of this document. 4.3 The main issues to be addressed by further possible changes to Reg. 5-1 and Reg. 7 + EN can be summarized as follows:a) The operational trim range of +/ 0.5%L within which no trimmed damage stability calculations need to be performed makes integration difficult with the intact stability limit curves from the 2008 IS Code, which cover the entire operating range of draught and trim. The fact that there may be no calculated information on the effect of trim on A could lead to significant underestimation of the safety margin (see example under 3.9, above) The removal at SLF 53 of this range threshold in Reg. 5-1.3 should help this problem but more work is needed on Reg. 7.2. b) Reg. 9.8 requires s=1 to be achieved after specified bottom damage in “all service conditions”, which is the same as the range specified in the 2008 IS Code. So there is a lack of consistency within the S2009 Regs which needs to be considered. c) The specification of a fixed trim for dl makes interpolation almost impossible, especially between the trimmed intact and damage limit curves for draughts between dl and dp. d) There are doubts over the equivalence of limiting GM and KG curves for trimmed conditions as KM, used to calculate GM, varies with trim whereas KG is independent of trim. e) Is there any technical reason why linear interpolation of a limit line between calculated draughts is more valid on the basis of GM than KG? f) There are circumstances in which there is no need to calculate a limiting KG/GM curve for A=R. The actual curve is quite arbitrary - there are many possible ways of varying the KG at dp and ds to achieve A=R.

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Round 5 Q1. Do you have any comments etc on the above? Are there any other items that need to be considered? Do you have any alternative thoughts? Please bear in mind that detailed changes to the above regulations to try to rectify some of the problems outlined are shown in Part 3 below, where comments can also be made at the end. Comments: CHINA: China noticed the difficulties with integrating KG/GM limit curves for intact and damage criteria which is caused by Reg. 5-1.3 and 5-1.4 EN1, but changes to regulation 7 may be inappropriate. Great changes will damage the continuity and cause confusion. We propose to just separate the intact and damage curves, and it will also be easy to check loading conditions separately. Using envelope curve may result in some loading conditions which can meet the intact and damage criteria separately failing to meet the requirements. It is our opinion that the envelope curve should be as a reference basis rather than mandatory requirements. Limiting GM curve is more meaningful in practical applications. We propose the master shall be only supplied with curves or tables of minimum operational metacentric height (GM). CLIA: No comments EC: See under Q3 FINLAND: • Very profound analysis of the current situation regarding reg. 5-1 and 7. In some details the summary seems to be very academic and as such this will be difficult to apply in practise with common design process. • Main purpose to compare GM- or KG-limiting curves we would like to consider that GM limiting curve is the primary curve. • The trim range of +0.5/-0.5 % Ls m should be maintained. • Same trim range for Dl should be kept and for dp and ds additional calculations shall be made, if trim range of +0.5/-0.5 % Ls exceeds. • The overall GM-limiting curve shall be derived as proposed by Norway In general we support changes to apply in reg. 5-1 and 7 proposed by Norway, which are shown in part 2 of this paper. GERMANY: • A very valuable summary of the current situation and the related difficulties, however the approach shown is in some parts very academic and not in line with the common design practice. • Many of the difficulties originate from the harmonization between cargo and passenger ship requirements. To keep a harmonized set of rules, some of the issues may remain. • To overcome the presented difficulties we would propose the following: o GM limiting curves are the primary source. If KG limiting curves are used, they are to be as such, that the same result can be achieved. o The trim range ±0.5% Ls is to be kept as this has been the basis for the sample ship calculation. The influence of the trim on the GM is acknowledged and accepted to keep a simple and consistent method for cargo and passenger ships

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GERMANY: (continued) For Dl the same trim range should be applied For other trim ranges additional calculations are to be made. Resulting in a clear determination of allowable trims for each draught o The overall GM limiting curve can be derived in the following ways. ƒ The envelope curve of the most onerous GM for each of the 3 draughts ƒ The calculation of other damage requirements (reg 8, 8.1 9.8) are to be included in these limiting curve. The same trim ranges are to be applied as above. o The result is one limiting curve for the damage requirements for the specified trims and various GM limiting curves for the different other intact criteria for different trims. o Modern onboard stability computers are capable to deal with different limiting curves. If a simpler approach is needed, the envelope curve of the most onerous requirements is to be used be used. This approach is implemented in the comments and proposals based on the Norwegian text. o o

•

ITALY: No further comments at this time. NORWAY: Our opinion is that the amended Norwegian proposal in part 2 will reduce most of problems mentioned in part 1. Please see answer to Q2. We have the following comments to the points raised by UK on page 23: 4 (a) We believe our proposal for a revised text of regulation II-1/5-1.3 and .4 in SLF 52/17/4 would reduce this problem. Part A, chapter 2 paragraph 2.1.7 and part B, chapter 3, paragraph 3.5.1 of the 2008 IS Code are relevant in the context and the need for harmonising a calculation tolerance with the SOLAS limit should be considered. (b) We understand this requirement to be limited to the calculated service conditions referred to in regulation II-1/7.2 (as may be amended). Removing the limitation for one trim only at dl and introducing a trim limit curve would seem to resolve this. (c) Agreed. This is another argument for removing that limitation. (d) Whether an initial KG or GM is selected for a given draught and trim should not matter with respect to the partial indices. As a selected value GM will be independent of KMt. Consistency problems arise in the range between dp and dl if KG is used, since the KMt for the two drafts will not be related at all when the trims are different. (f) For the sake of clarity we would like to recall the background for the envelope curve as discussed at SLF 49: Within the restrictions for partial indices in regulation II-1/6.1 the probabilistic method allows selecting combinations of high and low GMs at will as indicated in the sketch. Within the GM limits derived from these calculations there will be infinite combinations of future loading conditions that may or may not satisfy the required index R. For this reason a limiting GM for an arbitrary loading case cannot be found with absolute certainty by interpolating between discrete curves. The envelope curve assures that any loading within the trim limits defined by regulation II-1/7.2 will not be part of a combination of service condition where A would be less than R.

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In this example the trim in loading condition C1 is within the limits defined by trim 1 and 2, but the GM must comply with the envelope curve to ensure that it is part of a combination where A>R. We agree with UK that the EN should be modified to explain how the probabilistic envelope curve should be combined with curves for separate trims based on relevant deterministic regulations such as the IS Code. This could typically be compliance with the weather criterion at light draughts for certain ships. Our opinion is that the traditional interpolation between trims would still be acceptable in the regions where deterministic values govern minimum GM.

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POLAND: See under Q3 RINA: With regards to the above summary we would advise as follows: 4.3 a) It is noted that there is an inconsistency between the way current regulations require the results of intact stability and damage stability calculations to be presented differently and the problem this causes when developing a combined intact and damage stability GM/KG curve. It is considered essential that this issue is resolved in order to provide clear and understandable information to the ships Master. 4.3 d) From the consolidated working document it is noted that there a number of correspondence group members who have commented on the significant variation between KG and GM, when trim variation for a particular draught is taken into account. If this is the case is there a case for using either GM or KG, but not both, for the use in the intact and damage stability information? See also comments on Q 2 & 3. SWEDEN: An envelope limit curve can be optimized with the objective to either minimize GM or maximise VCG, whilst still complying with the stability requirements, within the allowed operating trim range. The optimum trim will diverse dependant on which criteria is used, illustrated in Fig A. As a consequence, a GM envelope curve is not relevant in the VCG environment, and if it should be drawn, conservative KMT values should be used, see Fig B MaxVCG(opt GM). Instead the limit curves for each trim curve should be used for transformation and then made into a envelope curve. In Fig B such envelope curve is drawn, MacVCG(opt VCG) on top of fig 10.

Fig A. Trim on x axis, meters on Y axis

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SWEDEN: continued

Fig B, parts of fig 10, drawn with the respective GM and VCG envelope limit curves drawn in the VCG environment. US: General: 1. We think maybe the figure 10 red “envelope curve” that is derived from the GM envelope in figure 8 is not correct for draughts 4.6, 4.8 and 5.0 (i.e. the funny dip in the curve). We think this stems from an error reading the KM values from figure 5 (i.e. the blue box KM figures on page 17). We attribute this to misreading the figure 5 KM scale where each division is .2m vice .1m. 2. We don’t understand the discussion about interpolation in paragraph 3.8 (page 22). We must assume that -0.9m trim is < 0.5% Ls so that the damage line is good for all trims up to whatever the 0.5% Ls limit is. Therefore it seems the -0.9m trim interpolation should be between level trim intact and -1m intact, and then it appears that this intact value will govern over the damage line value. (i.e. not sure why you would interpolate between the damage and intact curves?) 3. We also don’t understand the point being made in paragraph 3.9 (page 23). If the stability information plot GMs are not fully compliant with all the S2009 regulations (we assume this means regs 8 and 9.8?) then they can’t be approved (i.e. under your example the minimum GM at 5.7m draught on the plot would have to be 2.5m, not 1.1m).

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US: continued Comments: 1. For sake of simplicity in this discussion we tend to view the intact stability limits separately from the damage stability limits. In this way you can determine a minimum GM for intact requirements and a minimum GM for damage requirements, and then take the governing (highest) GM as the required GM for that specific condition. IS Code reg 2.1.7 requires that intact limit curves must cover the full range of operating trims, so any intermediate trim would be interpolated between the intact trim curve steps. For damage the same general principle would apply, although there are some additional difficulties with interpolation in the draught range between dp and dl, and also if the trim is < 0.5% Ls then we assume level trim is “close enough”. 2. Regarding interpolation for various damaged trim conditions in the draught range between dp and dl: Reg 7.2 requires the actual service trim for the light service draught in the “A” calculation, which in general seems reasonable since that load condition itself is rather fixed.* Given this situation and also the fact that intact stability limits tend to govern at the lighter draughts, we propose that the damage trim limit lines be extended from dp to dl as has been indicated by the dotted lines in figure 7. We think this is accurate enough and would solve the interpolation problem. (note: it seems this would require deleting the last sentence of current reg 5-1.3 and 5-1.4 EN 1) * However, we note several members have indicated that they need some variable trim range at dl (which this wouldn’t provide). We are not opposed to this, and it seems several “optional” dl trim conditions could be incorporated into the process. 3. The general consensus is that the required damage stability information must now encompass the full range of operating trims (already required for intact by reg 2.1.7). Therefore the question seems to be how many additional trim condition calculations are necessary to accomplish this? The current approach of within 0.5% of Ls does not seem sufficient for all ship types. We see potential options as: a. trim calculations (for ds and dp) at 0 trim and the maximum operational trim only (this has some similarity to part of the UK proposal in section 3). b. trim calculations (for ds and dp) at 0 trim and the maximum operational trim, and such additional trim calculations as necessary to ensure that trim calculation steps do not exceed [1%] of Ls. (e.g. if max operating trims were +2.8% and -0.4% of Ls; then option a: trim calculations at 0, +2.8% and -0.4% option b: trim calculations at 0, +1%, +2%, +2.8% and -0.4% of Ls) 4. We think the regulations and EN should allow flexibility to either: (1) interpolate between a series of minimum GM lines at different trims; (2) develop a single GM envelope curve (i.e. as in current EN 3 for reg 7.2); or (3) the Norway proposed alternative shown in EN 4 for reg 5-1.5 of section 2. This would seem to resolve the concern expressed in paragraph 1.7 on page 16. 5. Regarding the difference between min GM and max KG limits: We are not convinced this is a significant problem because reg 5-1.4 specifies the linear interpolation between draughts must be applied to GM values only. Therefore it seems all the limit curves/lines must be calculated with GM and then converted to KG (i.e. the interpolation lines on the

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GM plot will be curves on the KG plot). The Norway proposal for new reg 5-1.5 seems to indicate this point more clearly. 6. Also because intact stability tends to govern at lighter drafts, we do not think there is any need for additional damage stability calculations for draughts below the light service draft condition. The light service draft minimum GM should apply to any lesser draughts with respect to damage stability. Note: this comment is specifically related to the TOR .1 “consider what requirements for a minimum GM (or max KG) are applicable at draughts below the light service draught”. VANUATU: Several phrases in the text seem to us to be confusing with respect to full meaning. I wonder if we can use this comment to draw attention to them; 5-1 1 …“accurate guidance as to the stability of the ship under varying conditions of service.” Since this falls under Part B-1 of SOLAS, how would this apply to a heavy lift ship – for example? Are they excluded on the basis of footnote .7 of Regulation 4 as a vessel intended for the carriage of deck cargo? When ballasted down to take cargo aboard, are builders intended to be required to provide guidance to the Master for the loading operation; or are the “varying conditions” intended to describe underway conditions for conventionally designed ships? Para 2 under Regulation 5-1.3 and 5-1.4 for the heavy lift example above; does the phrase “light service draught” have the same meaning as for a conventional cargo ship? Regulation 7.5 para 6; “The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline, or higher.” In a heavy lift’s loading condition, the upwards without limit aspect of this rule would cripple the validity of further flooding considerations, if as it is likely, the crew were to de-ballast the hull in such a situation.

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Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) [and maximum permissible trim] Q18 versus draught which assures compliance with the relevant intact [stability requirements of part A of the 2008 IS Code] and [relevant] Q19 – proposed inserts not accepted damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability [according to the requirements of part A of the 2008 IS Code] Q19 – proposed inserts not accepted and stability after damage.

Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information. 3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls 3 The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board. Q20

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456) [; Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706)] Q6; and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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4 For ships which have to fulfil the stability requirements of part B-1, information referred to in paragraph 2 is determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way. 4 The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations. Information not required for determination of stability and trim limits should be separated from this information. 5 If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If it is intended to develop curves of maximum permissible KG it shall be ensured that the resulting maximum KG curves correspond with a linear variation of GM. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) and 5-1.5 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated. Q21 – to be considered in Round 5

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3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

4 As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed at the deepest subdivision draught ds and the partial subdivision draught dp respectively. The lowest values of each partial index As and Ap across trims will then be used in the summation of the attained subdivision index A according to regulation 7.1. At the light service draught the partial index Al is assumed constant. This will result in one GM limit curve based on the GM used at each draught. A trim limit diagram showing the assumed trim range is then developed as shown in the figure.

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5 It is not required that the trim values at ds and dp coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked at 0.5% Ls [L] in excess of the largest calculated trims as shown in the figure. There will be no trim limits in the draught range between dl and dp unless the limiting GM is governed by other applicable intact or damage stability criteria. When curves or tables of minimum operational metacentric height (GM) versus 56 draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition.

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Regulation 7 Attained subdivision index A 1 The An attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Q22 – to be considered in Round 5 A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1

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2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the each index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. The light service condition will be common for all calculations of index A.

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. Q23 and Q24 – to be considered in Round 5

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7 A previously approved partial index Al may be considered to remain valid for a sister ship and in other cases where differences in light ship particulars result in minor deviations from the assumed draught and trim in the light service condition. It is recommended that the limits for validity of stability documentation in case of lightship deviations set out in regulation 5.2 be applied also for this purpose. [Coordinator’s Note: please see Q24B in the working document for a possible amended version of this text]. 2 In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of Ls, one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. 2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The [actual] [anticipated] service trim shall be used for the light service draught dl. If in any anticipated service condition within the draught range from ds to dp the trim variation in comparison with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of A are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. The partial index Al is considered constant for the purpose of these calculations.

Regulation 7.2 1. The calculations for differing trim should be carried out with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. 3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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Q25 and Q26 – to be considered in Round 5 3 Each additional value of A calculated in accordance with paragraph 2 shall comply with regulation 6 and 7.1. 34 When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding Q27(2) and see Reg. 7.6 , the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. Regulation 7.3 “The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.” Q27(3) see Round 4 questionnaire The summation indicated by the above formula shall be taken over the ship’s 45 subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. Wherever wing compartments are fitted, contribution to the summation indicated 56 by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may

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be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 6 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only [to the centreline] to one half of the ship breadth B CLIA Q2 and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth. 3. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads. In the flooding calculations carried out according to the regulations, only one 67 breach of the hull and only one free surface need to be assumed [in the final stage of flooding]. Q27(2) and see Reg. 7.3 4. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. If pipes, ducts or tunnels are situated within the assumed extent of damage, 78 arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 8 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck. CLIA Q3

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2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than 2

[710 mm ] [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all [this] [these] small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]. CLIA Q4 see Round 4 questionnaire

Round 5 Q2 Do you have any comments etc on the above proposed changes by Norway? Do you have any suggested improvements or an alternative? Comments: CHINA: Please see the comments on Round 5 Q1 CLIA: We question the need for the option of using KG curves. Restricting the limits to be presented only as required minimum GM values would remove some of the issues being debated here. The requirement for use of a single envelope curve is questionable. When compared to using the correct GM minimum value for the actual trim (or interpolated between trims), the envelope will result in less GM margin and is too onerous. If GM limits are to be calculated for different trims (which involves a lot more work for the ship builder), why should they not be used as the GM limits for operation of the ship, with interpolation as required. These issues exist in the current regs// EN and the changes now proposed by Norway don’t address them. EC: See under Q3 FINLAND: • We support the changes proposed by Norway. • This is good approach to revise regulation 5-1 and 7 and EN. • We don’t have any improvements or an alternative. GERMANY: Reg 5-1 SOLAS Agreed to delete paragraph 4 The last sentence of the new para 4 should be deleted. New para 4: 4 The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations.

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GERMANY: (continued) The last sentence of para 5 to be deleted, small modifications in para 5: 5 If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If KG limiting curves are used as an alternative presentation, each GM limiting curve for the different trims need to be converted in corresponding KG values to achieve the same result as for interpolation of the GM curves. The KG envelope curve need to be achieved on the basis of these individual KG curves Reg 5-1 EN Para 1. Accepted Para 2: to be modified: 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims ensuring that intervals of 1% Ls are not exceeded. Also for the light service draught dl the trim range of ±0.5% of Ls applies and other trim ranges may be calculated. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve is achieved by overlapping the calculated trim ranges and should be clearly stated. The figure below shows an example of different trim ranges.

The red lines show the initial trim range, the green lines an alternative, extended trim range, the black lines the envelope trim range.

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GERMANY: (continued) The following diagram shows the corresponding GM limiting curves, together with the envelope curve in black

Para 3: Accepted Para 4: Not accepted, to be deleted Para 5: accepted except the last sentence. Slightly modified. 5 It is not required that the trim values at ds and dp coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked as shown in the figure. Para 6. Unchanged, only renumbered Reg 7 SOLAS Para 1: Change accepted Para 2: Slightly modified proposal: 2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The [actual] [anticipated] service trim shall be used for the light service draught dl. If in any anticipated service condition within the draught range the trim variation in comparison

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GERMANY: (continued) with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of the GM limiting curve are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. . The sets of GM limit lines are combined to give one envelope limiting GM curve. New para 3: not accepted Para 4 to 5: unchanged, accepted Reg 7 EN Para 1 to 4. Accepted Para 5: changes not accepted. Para 6: all reference to KG should be deleted: 6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs Para 7. Accepted Reg 7.2 EN Para 1 to 3: deletion accepted ITALY: No further comments at this time. NORWAY: Reconsideration of the proposals in Norwegian submission SLF 52/17/4 The proposals in that document were based on the assumption that the principle of using only one trim at the light service draught had to be maintained as a consequence of earlier decisions that the safety level must remain unchanged. At SLF 53 it was decided that this limitation need no longer be observed (see SLF 53/WP.1 paragraph 14.5). Consequently Norway is of the opinion that the principle of adding additional trims at the light service draught should be included in the calculation principles. The purpose is to take into consideration that substantial trim changes can occur in the range between dp and dl during normal operations. The notes below highlight what changes could be made to the Norwegian proposals if the trim restriction be lifted.

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NORWAY: Continued 1. Disregard paragraph 5 in SLF 52/17/4 2. In the Annex part A (Proposed amendments to regulations in chapter II-1 of SOLAS74 as amended):

Regulation 7 – Attained subdivision index A Instead of the proposal in 2.2 the proposed amendments to 7.2 replace the current text to cover principles discussed above. The word “actual” could be replaced with “estimated” to provide some flexibility if the draught and trim in the final stability calculations deviate moderately from preliminary results due to variations in the lightship particulars: “2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The estimated service trim may be used for the light service draught dl. If in any anticipated service condition within the draught range from ds to dl the trim variation in comparison with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of A are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls.” 3. In the Annex Part C (Proposed changes to the Explanatory Notes):

Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) Instead of the proposal in 1.4 of the annex the text of a new note 4 could read: “4 As an alternative to an envelope curve the calculations for additional trims may be carried out with one common GM for all of the trims assumed at each subdivision draught. The lowest values of each partial index As, Ap and Al across these trims will then be used in the summation of attained subdivision index A according to regulation 7.1. This will result in one GM limit curve based on the GM used at each draught. A trim [limit][envelope] diagram showing the assumed trim range is then developed as shown in the figure.”

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NORWAY: Continued Replace the previous figure:

s1

p2

p1 Draught

p3

s2

l2 0.5 L

0.5 L

l1

Trim

0.5 L 0.5 L

Instead of the proposal in 1.5 of the annex the text of a new note 5 could read: “5 It is not required that the trim values at ds, dp and dl coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked at 0.5% Ls [L] in excess of the largest calculated trims as shown in the figure.” Regulation 7.1 Paragraph 1.5 is replaced with:

In the proposal for a modified note 5 the word “each” is retained to cover multiple trims, but the last sentence should be deleted, i.e.: “5 Three initial loading conditions should be used for calculating each index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below.” Regulation 7.2 Note 1 should be deleted and note 2 will be redundant. 4. The other proposals in the annexes to SLF 52/17/4 remain as contained in the document.

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POLAND: See under Q3 RINA: Regulation 5-1.4 Agree with the proposal to consolidate intact and damage stability data. Regulation 5-1.5 Agree with the proposal to develop a single envelope limiting curve in the interests of clarity and uniformity. En 4 to regulation 5-1.4. If we are going to opt for a single envelope limiting curve it is not understood why we should want to develop an alternate solution which could cause confusion to the users. See also comments on the United Kingdom proposals. SWEDEN: No comments. US: 1. We generally support the Norway proposal. However, we think the regulations and EN should allow flexibility to either: (1) interpolate between a series of minimum GM lines at different trims; (2) develop a single GM envelope curve; or (3) the Norway proposed alternative shown in EN 4 for reg 5-1.5. Note: the proposed regulation 5-1.5 text currently mandates a single envelope curve only. 2. In the proposed alternative in EN 4 and 5 for reg 5-1.5, it indicates there are no trim limits between dp and dl (unless governed by other intact or damage criteria). Although we expect intact to govern for some or much of this range, this treatment needs more discussion. VANUATU: No comments.

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Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1

curves or tables of minimum operational metacentric height (GM) [and maximum permissible trim] Q18 versus draught which assures compliance with the relevant intact [stability requirements of part A of the 2008 IS Code] and [relevant] Q19 – proposed inserts not accepted damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves;

.2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability [according to the requirements of part A of the 2008 IS Code] Q19 – proposed inserts not accepted and stability after damage.

Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information. 3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls 3 The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board. Q20

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456) [; Guidance on the intact stability of existing tankers during transfer operations (MSC/Circ.706)] Q6; and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

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4 For ships which have to fulfil the stability requirements of part B-1, information referred to in paragraph 2 is determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way. 4 For ships which have to fulfil the stability requirements of parts B-1 and B-2, the limiting GM/KG information referred to in regulations 2.1 and 2.3 is determined from considerations of the appropriate intact stability criteria in combination with the damage stability criteria in regulations 8.1, 8.2 and 9.8. No limiting GM/KG curves/tables are to be calculated for demonstrating compliance with the criteria in regulations 6.1 and 6.2. Instead a note is to be added to the stability information provided to the master stating the achieved A/R ratio and partial indices at level trim and also at the extremities of the trim ranges forward and/or aft but only if these exceed +/-[0.2][0.5]% of L at any of the three draughts specified in regulation 7.1. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated. Q21 – to be considered in Round 5

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Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. The combined intact and damage limiting GM/KG curves/tables may be produced as follows:.1 Calculate the limiting GM/KG curves/tables for the appropriate intact stability criteria at suitable draught and trim increments across the operational range. .2 For the same draughts and trims calculate the limiting GM/KG curves/tables for the damage stability criteria in regulations 8.1, 8.2 and 9.8. .3 Combine all the results to determine the most onerous criteria across the trim range at specified draughts and produce limiting curves or tables of GM/KG for use by the master. .4 For the three draughts specified in Regulation 7.1 select, at level trim, the most onerous values of GM or KG at each draught (by linear interpolation if necessary) and use these values to calculate the attained subdivision index, A and the partial indices As, Ap and Al to demonstrate compliance with Regulation 6.1. .5 If the operating trim range exceeds +/- [0.2][0.5]% of L at any of the 3 draughts specified in Regulation 7.1, then repeat the calculation of A and the partial indices at the extremities of the trim range forward and/or aft using the appropriate limiting GM/KG for each draught / trim (by linear interpolation if necessary) to ensure compliance with Regulation 6.1. 2. If it is found that the attained index or partial indices do not meet the criteria in Regulation 6.1 then the subdivision arrangements must be improved and the procedure repeated until compliance is achieved. Compliance with Regulations 6.1 and 6.2 may not be achieved by increasing the GM (lowering the KG). 3. In addition to the curves/tables of limiting GM/KG the statement below should be added to the stability information booklet giving the calculated values of the A/R and the partial indices ratios to demonstrate compliance with Regulations 6.1and 6.2:“Provided the ship is loaded in accordance with the limiting GM/KG curves/tables, the ratio of attained / required index (A/R) at level trim for damage stability will be 1.xxx (minimum 1.000). At maximum operational bow trim the A/R ratio increases/decreases to 1.yyy and at maximum operational stern trim the A/R ratio increases/decreases to 1.zzz. At level trim the partial indices As, Ap and Al are x.xxxR, x.xxxR and x.xxxR respectively (minimum 0.9R or 0.5R, as appropriate) changing to x.xxxR, x.xxxR and x.xxxR at maximum operational bow trim and x.xxxR, x.xxxR and x.xxxR at maximum operational stern trim”. 5 When curves or tables of minimum operational metacentric height (GM) [or maximum operational (KG)] versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the [intact and damage] stability criteria are satisfied for this loading condition. Regulation 7

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Attained subdivision index A 1 The attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Q22 – to be considered in Round 5 A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σpi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula: i=t Ac = ∑ pi [vi si] i=1

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2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 to obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). Refer to the Explanatory Notes for regulations 5-1.3 and 5-1.4 for determination of the GM (or KG) to be used. The mean draught and trim are illustrated in the figure below.

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. Q23 and Q24 – to be considered in Round 5

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2 In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of Ls, one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. 2 In the calculation of A, level trim shall be used for the three draughts specified in regulation 7.1. If, at any of the three draughts, the maximum operational trim exceeds +/[0.2][0.5]% of L, further calculations of A are to be submitted for the same three draughts at the maximum operational trim forward and/or aft specific to each draught. Regulation 7.2 1. The calculations for differing trim should be carried out as described in the Explanatory Notes for Regulations 5-1.3 and 5-1.4. with the same initial trim for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). 2. Each combination of the index within the formula given in regulation 7.1 should not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. 3.

Example: Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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Q25 and Q26 – to be considered in Round 5 3 When determining the positive righting lever (GZ) of the residual stability curve in the final stage of flooding Q27(2) and see Reg. 7.6 , the displacement used should be that of the intact condition. That is, the constant displacement method of calculation should be used. Regulation 7.3 “The purpose of calculation of sequential flooding is to ensure that any intermediate flooding stage or phase will not lead to a lower si value. During intermediate phases of flooding, the added weight method is used and only one free surface needs to be assumed for water in spaces flooded during the current stage. In the final phase (full phase) of each stage the lost buoyancy [constant displacement] method is used, so one free surface is assumed for all flooded spaces.” Q27(3) see Round 4 questionnaire 4 The summation indicated by the above formula shall be taken over the ship’s subdivision length (Ls) for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. In the case of unsymmetrical arrangements, the calculated A value should be the mean value obtained from calculations involving both sides. Alternatively, it should be taken as that corresponding to the side which evidently gives the least favourable result. 5 Wherever wing compartments are fitted, contribution to the summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved. Additionally, cases of simultaneous flooding of a wing compartment or group of compartments and the adjacent inboard compartment or group of compartments, but excluding damage of transverse extent greater than one half of the ship breadth B, may be added. For the purpose of this regulation, transverse extent is measured inboard from ship’s side, at right angle to the centreline at the level of the deepest subdivision draught. Regulation 7.5 1. With the same intent as wing tanks, the summation of the attained index A should reflect effects caused by all watertight bulkheads and flooding boundaries within the damaged zone. It is not correct to assume damage only [to the centreline] to one half of the ship breadth B CLIA Q2 and ignore changes in subdivision that would reflect lesser contributions. 2. In the forward and aft ends of the ship where the sectional breadth is less than the ship’s breadth B, transverse damage penetration can extend beyond the centreline bulkhead. This application of the transverse extent of damage is consistent with the methodology to account for the localized statistics which are normalized on the greatest moulded breadth B rather than the local breadth.

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3. Where longitudinal corrugated bulkheads are fitted in wing compartments or on the centreline, they may be treated as equivalent plane bulkheads provided the corrugation depth is of the same order as the stiffening structure. The same principle may also be applied to transverse corrugated bulkheads. 6 In the flooding calculations carried out according to the regulations, only one breach of the hull and only one free surface need to be assumed [in the final stage of flooding]. Q27(2) and see Reg. 7.3. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent of damage will give a more severe result, such extent is to be assumed. 7 If pipes, ducts or tunnels are situated within the assumed extent of damage, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the Administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. Regulation 7.7 1. Pipes and valves directly adjacent to a bulkhead or to a deck can be considered to be part of the bulkhead or deck, provided the separation distance is of the same order as the bulkhead or deck stiffening structure. The same applies for small recesses, drain wells, etc. Valves which are situated as close as practicable to the bulkhead or deck, but exceeding due to their size the order of the stiffening structure should still be assumed to be part of the bulkhead or deck. CLIA Q3 2. The provision for allowing “minor progressive flooding” should be limited to pipes penetrating a watertight subdivision with a [total] cross-sectional area of not more than 2

[710 mm ] [an equivalent pipe diameter of Ls/5000] between any two watertight compartments. [The total cross-sectional area of all [this] [these] small pipes should [have a cross-sectional area of not more than] [not exceed] [an equivalent pipe diameter of Ls/1000]]. CLIA Q4 see Round 4 questionnaire.

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Round 5 Q3 The above proposed amendments are designed to deal with the problems outlines in Part 1. Do you have any comments etc on the above proposed changes by the UK? Do you have any suggested improvements or an alternative? Comments: CHINA: Please see the comments on Round 5 Q1 CLIA: We disagree with the concept given in 5-1.4. For ship designers, builders and operators, the presence of a fixed GM limit curve for ALL SOLAS damage stability criteria is essential, including the GM limit for A=R for reg 6-7. The damage limit curve should be the GM limits for whichever criteria is more onerous (Could be reg 8 if not reg 6-7). If the limiting criteria is Reg 8, then it is acceptable to state in the stability manual the A vs R value achieved at that limit curve. However, if Reg 6-7 is limiting, then the GM limit must be for A=R and the statement in the stability manual will simply state that at these GM values, Reg 8 and 9 are also achieved. The operator often needs to work close to the minimum GM values and needs to have a very clear graphical representation of what those values are. It is difficult to see how the UK proposal could be workable. In the UK suggestions for the EN, the suggestion that “Compliance with reg 6.1 and 6.2 may not be achieved by increasing GM” is not clear. The UK proposal for 7.2, is a good one but the wording needs some adjustment. There should be even keel damage calculations for all 3 draughts. Then, if the max trim is more than a certain % of L, there need to be calculations at the max trim (+/ -), and also intermediate trims such that the increments are not more than a certain % of L. Another way is to simply require damage stability calculations to be done at a range of trims, based on a specified trim increment. EC: Comments CG round 5 Please find below our response to the different questions to be considered in this round. In so doing, it is assumed that this response will also cover questions 1, 2 and 3 for round 5 in the subsequent parts of the questionnaire. Q21 EC could support the proposal from Norway concerning the amendments to Regulation 5-1, except that we have some reservations on par. 4, where it is stated that calculations for additional trims may be carried out with one common GM for all the trims assumed….. We do not understand the reason for using just one common GM and it seems not to be an accurate reflection of the actual situation.

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EC: Comments CG round 5 (continued) Q 22 The EC does not support the proposals for Regulation 7.1, but would like to propose the following alternative. We understand this alternative proposal comes at a late stage and is a bit more radical than the proposals so far. This alternative proposal stems from a research project commissioned by EMSA and that was carried out by the University of Strathclyde1 At the stage of submitting these comments the study has almost been finalised and it is expected to have the results presented at SLF 54, either by an INF paper, an oral presentation or both. The EC proposes to delete the formula for calculating the attained index in Regulation 7 for passenger ships. Instead we propose to require (in Regulation 6) each partial index to be not less than the required index R, so As ≥ R, Ap ≥ R and Al ≥ R. This would also make the requirement from Regulation 6.1 that the partial indices are not less than 0,9 R obsolete. The main reason for this proposal is that draught should be considered as a design parameter and for each draught the requirement A ≥ R should be met. For passenger ships we should not work with an 'average' stability'. It should not be allowed to compensate a worse stability at a certain draught with a better stability at another draught, even if there are limitations to what can be compensated. The requirement A ≥ R for each draught only needs to be tested at the 3 different draughts ds, dp and dp. The proposal is different from the earlier proposal from UK to weigh the partial indices equally for passenger ships. In that approach one is still able to compensate for cases with worse stability. More information on the background of the proposal can be found in the final EMSA2 report which will be made available to the CG. The intention is also to submit an INF paper to SLF 54 containing a short summary of the final results. Q 23 The proposal that the light service condition will be common for all calculations is not supported. If there are different trim situations possible at the light service condition, then this should be taken into account. Q24 EC could agree to the proposal to add a new par 7 if we delete the words 'and in other cases'. This latter is too vague and may open up for a lot of creativity. Q25 EC could support the proposal from Norway; we also believe there is some merit to the UK proposal to use max KG curves, which seem to be quite practicable. Q26 EC could support the proposal to add a new paragraph 7.3

1

Study of the specific damage stability parameters of Ro-ro passenger vessels according to SOLAS 2009 including water on deck calculation.

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EC: Comments CG round 5 (continued) Other issues In the research commissioned by EMSA some other issues were raised which may have a bearing on other questions that were dealt with in previous rounds, but not in round 5. This concerns: 1. An amendment to the formula for the s factor for ropax ships; and 2. The calculation of the required index; the report proposes to increase the value of R and use a different formula. This proposal may be combined with a removal of the K factor from the s-formula. By introducing a higher R-factor the safety level will be increased significantly. The question then is if this would fit into the TOR of the agenda item we are dealing with. More information on the above in the form of the results of the research project will be forwarded to the CG in due time and as stated earlier the EC intends to present the outcome at the next SLF meeting. FINLAND: We do not accept to use the UK approach. GERMANY: • Not accepted ! • Norwegian proposal is the better basis for additions and reflects the original agreed contents better. • The UK approach is too prescriptive how the design process should be made. This is up to the designer and should not be part of the rules. ITALY: No further comments at this time. NORWAY: Please see our answer to Q2. POLAND: I would like to present some comments to round 5 of the 2011 SDS CG questionnaire covering the following regulations and explanatory notes. Regulation 5-1 Stability information to be supplied to the Master. Regulation 7 Attained subdivision Index A. I would like to present some comments to stability Part B-1 Regulation 5-1 information to be supplied to the master Regulation 5-1 point 3. "The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5 % of Ls". I think that it is important to supply to the master information in this point connected with combined effect – results and influence of trim and the shape of the hull on GZ curve for the same displacement (forward trim and aft trim) The Master should know on the easy way how will present GZ curve when the trim will occur for different cases of displacement both in operation and in damage condition. This might be useful information for the master to make correct decision in case of damage of the ship.

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POLAND: continued As far as I am concerned this information could be applicable to passenger and cargo ships both in operation and taking into consideration stability in damage condition. RINA: EN regulation 5-1.3 & 5-1.4 The proposal usefully combines text from other areas of the document. The only concern that I would raise is that the proposed section looks more like Regulation than Explanatory Notes, which are non mandatory. See also comments on the Norwegian proposals. SWEDEN: The limit curves should cover all applicable stability criteria, including reg. 6.1 & 6.2 US: 1. This proposal is quite different. Conceptually we understand it to be a verification of damage stability compliance at level trim and the max trim conditions of an operating envelope based on the intact stability criteria (and possibly regs 8 and 9.8). 2. However, we question the feasibility of this. In proposed EN 2 for regs 5-1.3 and 5-1.4 it indicates a damage stability compliance failure can only be corrected by improved subdivision arrangements; not GM increases. At the ds condition we think the damage stability criteria is frequently more severe than the intact criteria, and we are not sure it is really feasible to increase the subdivision for compliance. VANUATU: is the intention in para 4, “For ships which have to fulfil the stability requirements of parts B-1 and B-2,” to solely address these requirement to vessels required to comply with both parts, rather than the original meaning that addressed meeting part B-1 only? Para .3 (and .4) under Regulation 5-1.3 and 5-1.4 – we believe the phrase “most onerous criteria” probably needs explanation before a decision can be made. Definition from Webster’s dictionary online defines onerous as involving, imposing or constituting a burden : troublesome – we’ve seen the UK use this word before in their MSC 85 paper on OSVs and simply describing something as “worst-case” may be a better choice of words than something as subjective as a synonym for “troublesome”.

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APPENDIX 5 •

NORWAY RE-CONSIDERED ITS ORIGINAL PROPOSALS FOR CHANGING REGS. 5-1 THROUGH 7.2 (INCLUDING THE EN) AS DETAILED IN SLF 52/17/4.

•

THIS APPENDIX SHOWS THESE REVISED PROPOSALS TOGETHER WITH SOME COMMENTS ON THEM TAKEN FROM THE ROUND 6 SUPPLEMENTARY QUESTIONNAIRE.

•

IN GENERAL THE 2011 CG MEMBERS PREFERRED THESE PROPOSALS BUT THERE ARE STILL SOME REFINEMENTS NEEDED AS INDICATED IN THE RESPONSES TO THE QUESTIONNAIRE BELOW.

DISCUSS AT SLF 54

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SOLAS Updates; SLF 54 Agenda Item 8; CG Round 5 response from Norway Changes to Regulations 5-1 through 7.2 and associated Explanatory Notes KEY TO COLOUR CODES and FONTS USED IN THIS DOCUMENT SOLAS Consolidated Edition 2009;

Current SOLAS text

Resolution MSC.281(85);

Current Explanatory Notes (EN)

Agreed Regulatory Text Changes

Changes to SOLAS agreed up to Round 4

Agreed EN Text Changes

Changes to EN text agreed up to Round 4

Q21

Reference to question in working document

SOLAS Consolidated Edition 2009;

Regulation text deletions SLF 51/17/4

SOLAS Consolidated Edition 2009;

Regulation text additions SLF 51/17/4

Resolution MSC.281(85);

EN text deletions SLF 51/17/4

Resolution MSC.281(85);

EN text additions SLF 51/17/4

SOLAS Consolidated Edition 2009;

Revised Reg. changes Sept. 2011 R5 CG

Resolution MSC.281(85);

Revised EN changes Sept. 2011 R5 CG

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Regulation 5-1 Stability information to be supplied to the master * 1 The master shall be supplied with such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service. A copy of the stability information shall be furnished to the Administration. 2

The information should include: .1 curves or tables of minimum operational metacentric height (GM) [and maximum permissible trim][Q18] versus draught which assures compliance with the relevant intact and damage stability requirements, alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of these curves; .2

instructions concerning the operation of cross-flooding arrangements; and

.3

all other data and aids which might be necessary to maintain the required intact stability and stability after damage. Regulation 5-1.2 Any limiting GM (or KG) requirements arising from provisions in regulation 6.1 (regarding partial attained subdivision indices), regulation 8 or regulation 9, which are in addition to those described in regulation 5-1.4, should also be taken into account when developing this information. 3 The stability information shall show the influence of various trims in cases where the operational trim range exceeds +/- 0.5% of Ls. The intact and damage stability information required by regulation 5-1.2 shall encompass the operating range of draught and trim. Applied trim values shall coincide in all stability information intended for use on board.[Q20] For ships which have to fulfil the stability requirements of part B-1, information 4 referred to in paragraph 2 are determined from considerations related to the subdivision index, in the following manner: Minimum required GM (or maximum permissible vertical position of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG values) of corresponding loading cases used for the calculation of survival factor si. For intermediate draughts, values to be used shall be obtained by linear interpolation applied to the GM value only between the deepest subdivision draught and the partial subdivision draught and between the partial load line and the light service draught respectively. Intact stability criteria will also be taken into account by retaining for each draft the maximum among minimum required GM values or the minimum of maximum permissible KG values for both criteria. If the subdivision index is calculated for different trims, several required GM curves will be established in the same way.

________________________ ∗

Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456); Guidance on the intact stability of existing tankers during transfer operations

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(MSC/Circ.706);[Q6] and the Revised guidance to the master for avoiding dangerous situations in following and quartering seas (MSC.1/Circ.1228).

4 The stability limits intended for use on board shall be presented as consolidated data taken from the applicable intact and damage stability calculations of these regulations. Information not required for determination of stability and trim limits should be separated from this information. 5 If the damage stability is calculated in accordance with part B-1 of these regulations a stability limit curve is to be determined using linear interpolation between the minimum required GM assumed for each of the three draughts ds, dp and dl. When additional subdivision indices are calculated for different trims, a single envelope curve based on the minimum values from these calculations shall be presented. If it is intended to develop curves of maximum permissible KG it shall be ensured that the resulting maximum KG curves correspond with a linear variation of GM. Regulation 5-1.3 and 5-1.4 (see also regulation 7.2) 1. Linear interpolation of the limiting values between the draughts ds, dp and dl is only applicable to minimum GM values. If it is intended to develop curves of maximum permissible KG, a sufficient number of KMT values for intermediate draughts must be calculated to ensure that the resulting maximum KG curves correspond with a linear variation of GM. When light service draught is not with the same trim as other draughts, KMT for draughts between partial and light service draught must be calculated for trims interpolated between trim at partial draught and trim at light service draught. 2. In cases where the operational trim range is intended to exceed ±0.5% of Ls, the original GM limit line should be designed in the usual manner with the deepest subdivision draught and partial subdivision draught calculated at level trim and actual service trim used for the light service draught. Then additional sets of GM limit lines should be constructed on the basis of the operational range of trims which is covered by loading conditions of partial subdivision draught and deepest subdivision draught ensuring that intervals of 1% Ls are not exceeded. For the light service draught dl only one trim is to be considered. The sets of GM limit lines are combined to give one envelope limiting GM curve. The effective trim range of the curve should be clearly stated. Q21 3 If multiple GM limiting curves are obtained from damage stability calculations of differing trims in accordance with regulation 7, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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4 As an alternative to an envelope curve, the calculations for additional trims may be carried out with one common GM for all of the trims assumed at [the deepest][each] subdivision draught [ds and the partial subdivision draught dp respectively]. The lowest values of each partial index As [and][,] Ap [and Al] across [these] trims will then be used in the summation of the attained subdivision index A according to regulation 7.1. [At the light service draught the partial index Al is assumed constant]. This will result in one GM limit curve based on the GM used at each draught. A trim [limit] [envelope] diagram showing the assumed trim range is then developed as shown in the figure. [

] [Replace the above figure:

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19th September, 2011

s1

p2

p1 Draught

p3

s2

l1

l2 0.5 L

0.5 L

Trim

0.5 L 0.5 L

] 5 It is not required that the trim values at ds [and][,] dp [and dl] coincide as long as the limitations with respect to variation between trims are observed at each draught. The applicable trim limits may then be marked at 0.5% Ls [L] in excess of the largest calculated trims as shown in the figure. [There will be no trim limits in the draught range between dl and dp unless the limiting GM is governed by other applicable intact or damage stability criteria]. 56 When curves or tables of minimum operational metacentric height (GM) versus draught are not appropriate, the master should ensure that the operating condition does not deviate from a studied loading condition, or verify by calculation that the stability criteria are satisfied for this loading condition.

Regulation 6 Required subdivision index R * 1 The subdivision of a ship is considered sufficient if the attained subdivision index A, determined in accordance with regulation 7, is not less than the required subdivision index R calculated in accordance with this regulation and if, in addition, the partial indices As, Ap and Al are not less than 0.9R for passenger ships and 0.5R for cargo ships. Regulation 6.1 To demonstrate compliance with these provisions, see the Guidelines for the preparation of subdivision and damage stability calculations, set out in the appendix, regarding the presentation of damage stability calculation results.

___________________________ *

The Maritime Safety Committee, in adopting the regulations contained in parts B to B-4,

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invited Administrations to note that the regulations should be applied in conjunction with the explanatory notes developed by the Organization in order to ensure their uniform application.

2 For all ships to which the damage stability requirements of this chapter apply, the degree of subdivision to be provided shall be determined by the required subdivision index R, as follows: .1

In the case of cargo ships greater than 100 m in length (Ls):

.2

In the case of cargo ships not less than 80 m in length (Ls) and not greater than 100 m in length (Ls):

where Ro is the value R as calculated in accordance with the formula in subparagraph .1. .3

In the case of passenger ships:

where:

.4

N

=

N1 + 2N2

N1

=

number of persons for whom lifeboats are provided

N2

= number of persons (including officers and crew) the ship is permitted to carry in excess of N1.

Where the conditions of service are such that compliance with paragraph 2.3 of this regulation on the basis of N = N1+ 2N2 is impracticable and where the Administration considers that a suitably reduced degree of hazard exists, a lesser value of N may be taken but in no case less than N = N1 + N2

Regulation 6.2.4 Regarding the term “reduced degree of hazard”, the following interpretation should be applied: A lesser value of N, but in no case less than N = N1 + N2, may be allowed at the discretion of the Administration for passenger ships, which, in the course of their voyages, do not proceed more than 20 miles from the nearest land.

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Regulation 7 Attained subdivision index A 1 The An attained subdivision index A is obtained by the summation of the partial indices As, Ap and Al, (weighted as shown) calculated for the draughts ds, dp and dl defined in regulation 2 in accordance with the following formula: Q22 A=

0.4As + 0.4Ap + 0.2Al

Each partial index is a summation of contributions from all damage cases taken in consideration, using the following formula: A=

Σ pi si

i

represents each compartment or group of compartments under consideration,

pi

accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, as defined in regulation 7-1,

si

accounts for the probability of survival after flooding the compartment or group of compartments under consideration, and includes the effect of any horizontal subdivision, as defined in regulation 7-2.

where:

Regulation 7.1 1. The probability of surviving after collision damage to the ship hull is expressed by the index A. Producing an index A requires calculation of various damage scenarios defined by the extent of damage and the initial loading conditions of the ship before damage. Three loading conditions should be considered and the result weighted as follows: A = 0.4As + 0.4Ap + 0.2Al where the indices s, p and l represent the three loading conditions and the factor to be multiplied to the index indicates how the index A from each loading condition is weighted. 2. The method of calculating the A for a loading condition is expressed by the formula: i=t

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Ac = ∑ pi [vi si] i=1

2.1 The index c represents one of the three loading conditions; index i represents each investigated damage or group of damages and t is the number of damages to be investigated to calculate Ac for the particular loading condition. 2.2 To obtain a maximum index a for a given subdivision, t has to be equal to T, the total number of damages. 3. In practice, the damage combinations to be considered are limited either by significantly reduced contributions to A (i.e. flooding of substantially larger volumes) or by exceeding the maximum possible damage length. 4.

The index A is divided into partial factors as follows: pi

The p factor is solely dependent on the geometry of the watertight arrangement of the ship

vi

The v factor is dependent on the geometry of the watertight arrangement (decks) of the ship and the draught of the initial loading condition. It represents the probability that the spaces above the horizontal subdivision will not be flooded.

si

The s factor is dependent on the calculated survivability of the ship after the considered damage for a specific initial condition

5. Three initial loading conditions should be used for calculating the each index A. The loading conditions are defined by their mean draught d, trim and GM (or KG). The mean draught and trim are illustrated in the figure below. [The light service condition will be common for all calculations of index A].

6. The GM (or KG) values for the three loading conditions could, as a first attempt, be taken from the intact stability GM (or KG) limit curve. If the required index R is not obtained, the GM (or KG) values may be increased (or reduced), implying that the intact loading conditions from the intact stability book must now meet the GM (or KG) limit curve from the damage stability calculations derived by linear interpolation between the three GMs. Q23 and Q24 7

A previously approved partial index Al may be considered to remain valid for a

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sister ship and in other cases where differences in light ship particulars result in minor deviations from the assumed draught and trim in the light service condition. It is recommended that the limits for validity of stability documentation in case of lightship deviations set out in regulation 5.2 be applied also for this purpose. 2 In the calculation of A, the level trim shall be used for the deepest subdivision draught and the partial subdivision draught. The actual service trim shall be used for the light service draught. If in any service condition, the trim variation in comparison with the calculated trim is greater than 0.5% of Ls, one or more additional calculations of A are to be submitted for the same draughts but different trims so that, for all service conditions, the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. 2 As a minimum, the calculation of A shall be carried out at level trim for the deepest subdivision draught ds and the partial subdivision draught dp. The [estimated] [actual] [anticipated] service trim [shall][may] be used for the light service draught dl. If in any anticipated service condition within the draught range from ds to dl the trim variation in comparison with the calculated trims is greater than 0.5% of Ls, one or more additional calculations of A are to be performed for the same draughts, but including sufficient trims to ensure that for all intended service conditions the difference in trim in comparison with the reference trim used for one calculation will be less than 0.5% of Ls. [The partial index Al is considered constant for the purpose of these calculations]. Regulation 7.2 The calculations for differing trim should be carried out with the same initial trim 1. for the partial and deepest subdivision draughts. For the light service draught, the actual service trim should be used (refer to the Explanatory Notes for Regulation 2.11). Each combination of the index within the formula given in regulation 7.1 should 2. not be less than the requirement given in regulation 6.2. Each partial index A should comply with the requirements of regulation 6.1. Example: 3. Based on the GM limiting curves obtained from damage stability calculations of each trim, an envelope curve covering all calculated trim values should be developed. Calculations covering different trim values should be carried out in steps not exceeding 1% of Ls. The whole range including intermediate trims should be covered by the damage stability calculations. Refer to the example showing an envelope curve obtained from calculations of 0 trim and 1% of Ls.

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Q25 and Q26 3 Each additional value of A calculated in accordance with paragraph 2 shall comply with regulation 6 and 7.1. R5-1 to 7.2 R5-1 to 7.2 EN Discussion for Round 6 Supplementary Questionnaire. Changes to Regulations 5-1 through 7.2 and associated Explanatory Notes NORWAY: Reconsideration of the proposals in Norwegian submission SLF 52/17/4 The proposals in that document were based on the assumption that the principle of using only one trim at the light service draught had to be maintained as a consequence of earlier decisions that the safety level must remain unchanged. At SLF 53 it was decided that this limitation need no longer be observed (see SLF 53/WP.1 paragraph 14.5). Consequently Norway is of the opinion that the principle of adding additional trims at the light service draught should be included in the calculation principles. The purpose is to take into consideration that substantial trim changes can occur in the range between dp and dl during normal operations. R6-SQ1 for Round 6 Supplementary Questionnaire. Given the large support in Round 5 for Norway’s original proposals in SLF 52/17/4 and bearing in mind that some square bracket issues still need to be resolved can you, in general, accept Norway’s revised proposals included in their response to the Round 5 questionnaire (shown below) or do you think these regulations and EN still need to be discussed in detail at SLF 54 before any text changes are finalized? Accept Norway’s new proposal?

CLIA (In general, yes. But we still question the benefit of the option to use KG curves. The proposals to ensure full consistency between GM limit curves and derived KG limit curves are important. The concept of a single envelope curve, even when GM limits have been calculated for different trims still seems to be present. That is unduly onerous. If limits for trims have been calculated, it should be possible to use them in operation. But we believe that these issues actually have little impact on our vessels, which usually have limited trim).

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Wait until SLF 54 to discuss the issues?

Germany (Yes, but the final clean version should be explained and discussed again at SLF54), Finland, Norway, US (subject to some additional refinements) EC (In general yes, except for the parts on the partial indices and the weighing thereof. The on-going research will result in some proposals for amending SOLAS 2009 on the part of the partial indices, so we think that we should at least have a look what will be presented and discuss. The results of the research will also focus on the R-factor, which we think should also be discussed.) RINA, China, Finland (with comment), Poland (Regulations and EN still need to be discussed in detail at SLF54 before any text changes are finalised.), Vanuatu (Prefer this approach for some of the detailed issues), UK, France (see comment)

Further comments / alternatives?:Japan: No comments. Finland: Even if we accept Norway’s proposal, we wish to discuss it in detail at SLF54 due to the importance of this item. Germany: Reg 5-1.4 The last sentence should be made clearer. Which information should be separated. EN for 5-1.4: here is still mentioned that there is only one trim at Dl. To be changed to trim range Both figures to illustrate the trim ranges are not self explaining and need to be improved. An alternative proposal please find enclosed (shown below):-

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New proposal from Germany German proposal for a draft text about extension of the GM-limiting curve up to drafts acc. to tropical freeboard incl. fresh water allowance: “If a vessel is permitted to sail at drafts above the subdivision draft ds, the GM-limiting curve may be extended up to that draft, but not exceeding the tropical freeboard draft, by taking over the GM at the subdivision draft ds as constant for all drafts above ds. The increased draft due to the freshwater allowance may be taken into account the same way.” Vanuatu: We need to fully explore the intent behind SLF 52/17/4 Annex 2 page 2 B proposed change to regulation 4 footnote. Otherwise we are generally in agreement with their proposals. US: We definitely support this approach; it should allow us to refine and finalize this text at SLF 54. UK: Before accepting the proposed method on alternative limiting curve determination, we would like to see sufficient evidence that any condition which falls outside of a calculated point within the outer side of 0.5%Ls trim variation limit - would not be failing any requirements of part B-1. France: France is of the opinion that, if a common curve for all trim is retained, it would be better to have a maximum KG curve, because GM is too much sensitive to trim variations.

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