Anchoring Safely

October 16, 2017 | Author: nikoskarandinos | Category: Anchor, Rotation Around A Fixed Axis, Clutch, Ships, Transmission (Mechanics)
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The Steamship Mutual Underwriting Assoc iation [B ermuda l Limited

VID EOTEL PR ODUCTIONS ANCHORING SAFELY

ANCHORING SAFELY

A VIDEOTEL PRODUCTION

In association with

The Steamship Mutual Underwriting Association [Bermuda] Limited

AUTHOR

Johnathan Priest

rnVIDEOTEL

productions

wn

84 Newman Street , London 3EU Telephone : +44(0]20 7299 1800 Facsimile: +44(0]20 7299 1818

E-mail: mail0videotelmail.com

VIDEOTE l PRODUC TIONS ANCHORING SAFELY

ANCHORING SAFE Y

A VIDEOTEL PRODU CTION

In association with

The Steamship Mutual Underwriting Association [Bermudal Limited

THE PRODUCERS WO ULD LIKE TO ACKNOWLEDGE THE ASSISTANCE OF

The Master, Officers and Crew of MV Berge Nord

Bergesen d .y. ASA

International Maritime Organization

The Maersk Company

The Steamship Mutual Underwriting Association [Bermudal Ltd

United Salvage Ltd

Warsash Maritime Centre

World Wide Shipping

CONSULTANTS Sir William Codrington

Captain Allan MacDowall

PRODUCER Peter Wilde

WRITER/DIRECTOR Charles Leigh-Bennett

PRINT AUTHOR Johnathan Priest

WARNING Any unauthorised copying, hiring, lending, exhibition diffusion, sale, public performance or othe'r exploitation of this video is strictly prohibited and may result in prosecution .

© COPYRIGHTVideotel2005 This video is intended to reflect the best available techniques and practices at the time of production, it is intended purely as comment. . No responsibility is accepted by Videotel, or by any firm, corporation or organisation who or which has been in any way concerned, with the production or authorised translation, supply or sale of this video for accuracy of any information given hereon or for any omission herefrom

VI DE OTE L PRO DU CTION S AN CHORING SA FELY

INTRODUCTION

4

What subject does this training cover?

4

How to use this guide?

4

What does this guide provide for trainers?

4

SECTION 1 ANCHORING - THE HAZARDS

5

SECTION 2 ANCHORING EQUIPMENT

6

2.1

The anchor

6

2.2

The windlass

6

2.3

Preventing d amage to the windlass motor and clutch

7

2.4

Preventing damage to the windlass brake

8

SECTION 3 PREPARING TO ANCHOR 3.1

Lying at single anchor

3.2

Basic procedure

SECTION 4 ANCHORING A VERY LARGE VESSEL

·9

9

10

12

4.1

Is equ ipment keeping pace?

12

4.2

The traditional Fore & Aft [in-line] approach

13

SECTION 5 AN ALTERNATIVE APPROACH TO

ANCHORING

16

5.1

The U-turn m ethod

16

5.2

Axial verses rotational forces

16

SECTION 6 USING THE U-TURN METHOD

18

6.1

Operational br iefing

18

6.2

Approach to anchorage

19

SECTION 7 ANCHOR WATCH AND SECURITY

21

SECTION 8 WEIGHING ANCHOR

22

SECTION 9 CONTRIBUTORS

24

3

VIDEOTEL PR ODUCTIO NS ANCHORING SAFELY

WHAT SUBJECT DOES THIS TRAINING GUIDE COVER? This training guide examines the general principles of safe anchoring for medium to large vessels including VLCCs and bulk carriers . The need to review anchoring procedures is born out of an increased incidence of personal injuries, damage to anchoring equipment and even loss of ships caused by the difficulties of anchoring large vessels. An overview is provided of the proper use of anchoring equipment and its mechanical tolerances. An alternative to the traditional approach to laying anchor is also described.

HOW TO USE THIS GUIDE? The guide is published in an association with a video of the same title 'Anchoring Safely' which provides an overview of anchoring and which demonstrates some of the techniques described herein. The guide provides the theoretical background to anchoring procedures demonstrated in the video and describes them in far greater detail. To this day, anchoring remains a hotly debated topic and companies and their masters have strongly hel.d opinions as to how it should be carried out, many of which are also a matter of company policy. The publishers wish to make it clear that the information provided in the video and guide is based on widely accepted best practice but is in no way intended to provide anything other than guidance .

WHAT DOES THIS GUIDE PROVIDE FOR TRAINERS? This video and guide provide trainers with a concise overview of the basic principles of safe anchoring and will help them to increase awareness of this vitally important aspect of seamanship. The procedures described are based on a sound understanding of engineering tolerances of anchoring equipment and the dangers to personnel and equipment associated its misuse. The main procedures for laying and weighing anchor are described as well as the requirements for anchor watch . The trainer's experience and expertise remain essential in interpreting these procedures in the context of the variety of physical conditions and local constraints that mariners will encounter.

4

VIDEOTEL PRODU CTIONS AN CHORING SAFELY

ANCHORING - THE HAZARDS Anchoring is a highly skilled operation that requires leadership, teamwork and the utmost vigiLance from the time the ship arrives at port to the moment the anchor is weighed. Ships often have to go to anchor unexpectedly either due to changes in berth availability or weather conditions. Anchors and windlasses need to be well maintained and ready for use at any time in port approaches and harbours. Pressure on berths around the world means that merchant ships may have to remain at anchor for long periods . This is demanding on masters, pilots and crews, especially on the largest vessels where exceptional care is required to anchor safely and without causing damage to other shipping or port facilities. There have been increasing reports of accidents to ships while lying at anchor including drifting, collision and stranding caused by dragging. Many accidents and equipment losses also occur when the anchor is being laid or weighed. Reported incidents tell of vessels losing the anchor due to the cable parting, of vessels whose windlass brake caught fire and more than one vessel whose cable was pulled from the locker with such force as to not only part the bitter end, but fracture the bulkhead on which it was mounted. A major consideration is that such inc idents are often associated with personal injuries and even loss of life and is therefore a concern for ship owners and masters alike. It is an unfortunate fact that many of these accidents have been caused by poor basic seamanship and failure to plan ahead. The advent of very large vessels such as VLCCs and bulk carriers has added to these concerns, where not only are the costs and consequences of anchoring accidents that much greater, the technical challenge of anchoring such large vessels is also greatly increased. It is therefore timely to review anchoring procedures and to see how the risk of accidents can be reduced. to a minimum.

5

VIDEOTEL PRO DUCTI ONS AN CHORIN G SA FELY

ANCHORING EQUIPMENT 2.1 THE ANCHOR The requirement of an anchor is to bite firmly into the sea bed, provide enough holding power and to remain in the right position without overturning even when pulled over the sea bed. The total mooring power of an anchor is the sum of the holding power of the anchor combined with the resistance created by the cable on sea bed. The cable also has an important role in maintaining the stability of the anchor. Maritime vessels are generally equipped with 11 to 14 shack les of cable, each shackle being 27 .5 metres in length. The amount of cable paid out will vary according to the depth of the water and the conditions and this will be specified as part of the anchoring plan.

2.2 THE WINDLASS Oamage to anchoring equipment and numerous personal injuries have been caused by incorrect use of the windlass . A typical example of misuse is the windlass motor [rather than the brake! being used to payout the cable . This may result in motor over-pressurisation causing excess internal surface to surface forces and then fracture of the motor casing . If the windlass brake is misused, the lining can in extreme cases actually catch fire, a situation often compounded by inadequate maintenance .

ANCHORING EQUIPMENT SPECIFICATION for 150,000 tonne deadweight ship

ICab le "4"."M"9""'i't',In'

Spur li ng pip e

From the diagram, you can see that the only piece of equipment on board that is designed to take the full weight of the vessel is the bow stopper, with a rating of 480 tonnes. By contrast, the windlass motor has a lifting power of just 32 tonnes [3 shacklesl or 38 tonnes [4 shackles!' It is designed to lift or lower an anchor and three shackles of cable through a maximum of 82 meters of water in a verticallift.l

6

I

Th ere IS a pro posa l by th e lACS (Inte r national Asso cIatI on of Cla sslflcalion Soc ietles l that the wi ndlass should be capable 01 lifting th e an chor and cabl e in 110 me r s of wat er The wind speed of 14 m/sec 128 knots l. and a three kn ot curre nt l unchangedl. at a speed of 0 I Sm/ se c 19 m/m in i tho ugh thi s has not been adopted . Alm osl all ships are deSigned to the 82 metre rule .

VIDEOT EL PR ODUCTIONS ANCH ORING SAFELY

The crew should have a clear understanding of the implications of any variation from the vertical [up-down] position of the cable while the anchor is being manoeuvred. Any angle out of the vertical indicates horizontal force that includes part of the ship 's mass, which strictly speaking is not allowed for in the specification. Any changes in the alignment of the cable relative to the hull should be communicated to the bridge immediately so that the position of the ship can be altered to remove the load on the cable.

A 150,000 tonne deadweight ship has the following anchor equipment rated 'as new' according to the Classification Society rules:

LIFTING POWER OF ANCHOR WINDLASS

38 TONNES FORCE

WINDLASS BRAKE HOLDING POWER

279 TONNES FOR CE

CABLE STOPPER

S,~FE

WORKING LOAD

480 TONNES FORCE

ULTIMATE TENSILE STRENGTH OF CABLE

600 TONNES FORCE

LENGTH OF 1 CABLE ­ I SIDE

13 SHACKLES

WEIGHT OF 1 SHACKLE OF CABLE

7.2 TONNES FORC E

WEIGHT OF 1 ANCHOR

10.6 TONNES FORCE

Tankers are also fitted with two bow stoppers each rated at 200 tonnes force for SBMs.

2.3 PREVENTING DAMAGE TO THE WINDLASS MOTOR AND CLUTCH Whether electric, hydraulic or steam, the windlass is designed purely to control the weight of the anchor and three [or fourl shackles of cable. In particular, the windlass gearbox should not be used as a low ratio box as in a motor vehicle where the gears are used to slow its descent down hill. If the gear bo x is subject to such reverse forces, serious mechanical damage is likely to result. Exceeding the designed limits of hydraulically powered windlasses will cause the system to become over pressurised. If bearing pressures within the motor are exceeded, metal will be shaved off its components . These shavings pass through the coarse filter and into the pump . Further increase in bearing pressure can cause the casing to crack . In such a situation, the veered cable cannot be recovered. External forces applied to the valve/slide gear of steam windlasses will cause the drive to be driven. This can result in failure of the eccentric. The dog clutch may jump out of engagement due to the parting force at the dogs and the clutch operating fork will deform from its bed within the annular groove on the dog.

7

VIDEOTEL PRODU CTI ONS ANCHORING SAFELY

Failure to insert the clutch lever securing pin will also lead to clutch disengagement. If the faces are badly worn, the clutch can jump out of gear even if the clutch operating lever is properly pinned because the fork is not sufficiently strong to resist the force pushing the dogs apart. The fork may also have become distorted.

2.4 PREVENTING DAMAGE TO THE WINDLASS BRAKE The windlass brake, not the motor, should be used for paying out the cable. This is because the brake has a rated static applicable force some 10 times that sustainable by the motor. However, use of the brake relies heavily on the skill of the crew and the proper 'as new' maintenance of the brake mechanism. On larger vessels, the brake should always be manned by two crew members as the rated force cannot be applied by one man alone. A NUMB ER OF SITUAT IONS WILL LEAD TO BRAKE DAMAGE • Brake has been screwed up tight but the vessel's momentum

causes it to slip

• Slipping causes heat generation and the brake to fade • Heat causes the brake band to expand and so become less tight • Heating by friction causes the brake to fade even more LIKE THE MOTOR. THE BRA KE HAS VERY SPEC IFIC DES IGN LIMITATIONS: • The windlass brake is designed to control the cable running out

and to stop it vertically without the ships weight on it

• The windlass brake is not designed to arrest the motion of the ship • The windlass brake is not designed to hold the mass of the ship

Brake use should ideally be practiced a minimum of once a month for each windlass. Failure to do this will quickly lead to seizure of parts because sea water causes very rapid rust build-up . Talking through the procedure is also a helpful way to remind crew of the precise sequence of events. In an emergency, having the skill and ability to drop the anchor will save the day. Use of the motor rather than the brake could have insurance implications due to improper use of equipment. The bow stopper must be engaged and the motor declutched when the drop is finished, with the cable in the up and down position . As you can see from its load specification, the bow stopper has 1.7 times the holding power of the brake and is the only piece of equipment that is designed to take the full load of the ship at anchor. However, in order to be effective, the bar of the bow stopper must lie on the horizontal link with the locking bar in place with no gap that could allow the tongue to lift, otherwise the bow stopper could ride over the vertical link when weight comes on the cable and distort the locking bar.

8

VID EOTEL PRO DU CTIONS AN CHORING SAFELY

PREPARING TO ANCHOR Advanced planning and excellent communications between the bridge and the anchoring team are essential to safe anchoring. The master will ensure that the crew is trained in the use of the anchoring equipment and has access to accurate and up-to-date information about the anchorage so that an anchoring plan can be prepared. The master should select an anchorage that is sheltered, with good holding ground and an appropriate depth, depending on the ships own manoeuvrability and conditions. Weather and sea conditions and dangers such as submarine cables, pipes and wrecks should all be taken into consideration.

3.1 LYING TO A SINGLE ANCHOR Although the method varies depending on the depth of an anchorage, lying at a single anchor is most frequently used because of its handling simplicity when dropping and weighing anchor. In this pattern the anchor is usually let go under very slight sternway. The ship 's speed is reduced according to the plan, the engine is stopped just before the anchorage and ships advances only by its momentum. The engine is put astern just before the anchoring point so that the ship stops at the intended spot. The anchor is let go just after the ship is dead in the water.

9

VIOEOTEL P ODUCTIO 5 ANCHORING SAFELY

3.2 BASIC PROCEDURE Here is the basic procedure for anchoring a small to medium size vessel:

BEFORE ARRIVAL AND AS PART OF THE ANCHORING PLAN • Select the position of the anchorage and plan the approach • Determine how to reduce the ship's speed from the initial approach to the intended anchorage • Establish the depth of water, nature of bottom, which anchor to use and how much cable to payout • Decide manning for anchoring including the personnel on bridge, engine room, fo'c'sle, pilot ladder or gangway if required • Brief the anchoring team

SHORTLY BEFOR E ARRIVAL • Clear the anchors, hawse and spurling pipes • Test the windlass and brake • Test communications • Prepare to display anchor signal. (ball daytime, lights at night]

ON NEARING THE ANCHfJRAGE , AMEND TH E PI..AN TO INCORPORATE: • Other ships in the anchorage • Local weather and sea conditions • Local navigation warnings and regulations • Orders from the authorities • Advice from the pilot or Vessel Traffic Services

APPROACH THE ANCHORING POSITION BY HEADING INTO THE PREDOMINANT FORCE IEITHER WIND OR CURRENT/TIDAL STREAM, USUALLY THE LADER)

TAKE WAY OFF THE SHIP AND THEN MAKE VERY SLIGHT STERNWAY

LET GO THE ANCHOR. CONTROLLING WITH THE BRAKE ONCE THE ANCHOR IS ON THE SEA BED AND SLOWLY PAYING OUT AS THE SHIP MOVES ASTERN

DISPLAY THE PROPER SIGNAL FOR A VESSEL AT ANCHOR AT NIGHT, SWITCH OFF THE STEAMING L1GH S

10

VIDEOTEL PROD U CTIO N S ANCHORING SAFELY

KEEP THE BRIDGE INFORMED WHETHER THE CABLE IS TIGHT AND HOW IT IS LEADING , tOR EXAMPLE "UP AND DOWN" OR '·TIG HT AND LEAD IN G' TELL THE MASTER HOW MANY DEGREES THERE ARE BETWEEN THE ANCHOR AND THE BOW, SO THAT HE CAN ASSESS WHETHER THE ANCHOR IS UNDER ANY STRAIN

WHEN THE CABLE HAS BEEN PAID OUT TO THE AGREED SHACKLE MAR K ['FOUR IN THE WATER ' "SIX ON DECK : OR SIMILAR!, THEN APPLY THE BRAKE THE BOW STOPPER SHOULD THEN BE APPLIED AND SECURED WITH THE PIN, THE SHIP SHOULD BE STOPPED OVER THE GROUND US IN G THE ENGINE

WAIT FOR THE CABLE TO COME TAUT AND THEN SLACKE N TO SHOW THE SHIP IS ' BROUGHT UP" (WATCH FOR THE CABLE GO IN G TA UT AND THEN SLACK, TAUT AND THEN SLACK, OR JUDDERING WH ICH MEANS THE ANCHOR IS DRAGGING)

CHECK THAT THE BRAKE IS SCREWED UP TIGHT AND THE BOW STOPPER SECURE.

SET ANCHOR WATCH ON THE BRIDGE AND SECURITY WATCHES

DISPLAY ANCHOR LIGHTS / ANCHOR BALL

11

VIDEOTE L PRO OU CTI O S ANCHORING SAFELY

ANCHORING A VERY LARGE VESSEL

SECTION 4

4.1 IS EQUIPMENT KEEPING PAC E? While the general principles described for small to medium sized vessels also apply to very large vessels such as VLCCs, the hazards associated both with Laying anchor and while lying at anchor are greater with a large vessel, as are the likely consequences of any accidents. It is a widely held belief that these failures are in part due to the specifications of anchoring equipment not keeping pace with the increasing size of vessels . However, an examination of classification society specifications reveals this not to be the case . In the vast majority of incidents, accidents are related to a combination of inadequate preparation for anchoring, poor seamanship, lack of communication between bridge and fo' c'sle, misuse of anchoring equipment and inappropriate anchoring procedures. Concerns about the increased risks associated with anchoring very large vessels have led some companies to issue instructions to the effect that the anchor must be walked out all the ,

1

way, regardless of the depth in which the vessel might be anchoring.

I

,.~'

DESIGN CRITERIA - EQUIPMENT LETTER Derived from: f:... 113 ';' 2BH Where:

=

i

AIIO

SUMMER DISPLACEMENT IN TONNES

B'= MOULDED BREADTH IN METRES H = SUMMER FREEBOARD IN METRES ,I:J., =

AREA OF THE PROFILf OF THE HULL IN SQU RE METRES

The various classification societies arrive at the equipment letter through the above formula which confirms that the design capabilities are directly related to the size of the vessel,

12

VIDEOTEL PR ODUCTI O S ANCHORING SAFELY

SECTION 4

4.2 THE TRADITIONAL FORE & AFT (IN-LINE] APPROACH In the traditional in-line approach, where the anchor is laid in line with the ship's fore and aft axis, walking the anchor and cable back the whole way is permissible, provided the cable is kept up and down the whole time and that the design speed of the windlass is not exceeded. While this is easy enough to say in practice, with a very large vessel thiS is a difficult manoeuvre and risk of damaging the windlass is relatively high .

I

I

...... .

~

,

13

VIDEOTEL PRODUCTIO I S ANCHORING SAFELY

SECTION 4

A WORST CASE SCENARIO A vessel is to anchor in the traditional in-line method. The anchor is walked back just clear of the water, the engines are put astern and when the wake has reached the bridge wing the engines are stopped and the order given to let go. The cable is allowed to run freely as the vessel moves slowly astern. At eight shackles on deck the cable is snubbed and at ten on deck, the brake is screwed up tightly. Inability to arrest the vessel within the very small distance twixt up and down and bar taught results in a cable with no elasticity left. Even though the brake is screwed up tightly, the vessels momentum exceeds the brake's 279 tonnes resistance and the brake begins to fade. Fading causes heat generation which, through volumetric expansion, enlarges the internal diameter of the brake band, thus allowing more fading. Despite checking the astern motion, the motion of the vessel is too great and it continues to move astern. The brake band is now so hot it has expanded such that the cable is now accelerating . Before the vessel can be brought to a complete stop, the three remaining shackles have been drawn from the locker. Detachment of the bitter end or certainly deformation of the chain locker is likely to follow. The momentum of the cable and its direction of motion are such that the cable will leave the gypsy and arc above it. When the end finally parts, energy within the cable is quite sufficient to punch a hole through 20mm plate and carry away any deck fittings in its path . Given that putting out 10 shackles with the motor takes in excess of half an hour at 5cms per second, it is exceedingly difficult, especially with larger, diesel-powered vessels, to control sternway to such a fine degree. The long period of time required to payout the anchor cable sometimes leads to masters using less cable than they should. There have been incidents where this has lead to anchor dragging and consequent grounding. Even the most experienced master may run into difficulties and this is because the traditional approach to anchoring already places him at a mechanical disadvantage.

Take the example of a vessel anchoring in 50 metres of water with 10 shackles: The difference in horizontal distance between the position of the vessel when the cable is up and down and if, it became bar taut would be approximately 50 metres. Now, a 150,000 tonne vessel has a beam approaching 50 metres. So the challenge is easy to visualise; the master is trying to stop a ship of say 300 metres within a distance roughly equal to its beam.

14

VID OTEL PRODU CTIO NS ANCH ORIN G SAFELY

SECTION 4

ANCHOR ON SEABED

THE TRADITIONAL FORE &

AFT (IN-LINE) APPROACH

~

~

~

TIDE AND WIND

The engines should be used to take sternway off the ship. Failure to halt the astern movement will result in a bar taut cable with no elasticity left because all the catenary has been taken up. The full mass of the ship comes onto the windla ss. The force now being exerted on the windlas s is now about 1000 times maximum allowed l

15

VIDEOTE L PRO DUC-I IONS ANCHORING SAFELY

AN ALTERNATIVE APPROACH TO ANCHORING 5.1 THE U-TU RN METHOD The U-turn or more precisely, orthogonal method of anchoring has a long historical precedent and has been the practice of a number of masters for many years. Its benefits have also been discovered during emergencies when the master's quick reactions and knowledge of how to lay anchor on the move have saved the day. However, prior to the mathematical and mechanical analysis carried out by Captain Allan McDowaW, such a procedure could not become mainstream and owners would have been reluctant to incorporate it into their operational procedures . The procedure is not without risk and its success depends on the crew having a clear understanding of the procedure with appropriate training in the use of the equipment. Because timing is critical, excellent communications must be maintained between bridge and fo·c'sle. Masters and crews who have not used this method before should ensure that adequate sea room is available. With experience however, the manoeuvre can be safely completed within a relatively compact area.

5. 2 AXIAL VERSU S ROTATIONAL FOR CES The secret of the U-turn approach to anchoring lies in separating the momentum of the ship's hull from the forces necessary to control the movement of the cable. Consider a block shaped vessel, it has a block coefficient of 1. The force required to accelerate the vessel in the fore and aft line is three times that required to rotate it about its pivot point . That is why it is easier to push a small sailing boat sideways or rotate it round its axis than move it in the fore aft line.

The force required, at the stern, to ') IE the vessel in a straight line is approximately three times that required to TU RN the vessel by applying a force at right angles to the stern

It follows that to decelerate the same block in rotation would be one third the force required to stop its axial momentum .

TURN a stationary vessel

Force

16

r"qulrecl

10

ID!~E.



' Anchomg I_arge Vessels - A new ap pro ach . Ca pt C. A. McDowall . The Naut ical lnsll tute, 202 Lam beth Road, Lon don SEI 7LQ. ISBN 1 87077 56 3

VIDE OTEL PRO DUCTI ONS ANCH ORING SAFELY

This difference is because rotational inertia is less than the axial inertia; it is a change from straightforward linear acceleration to one of angular acceleration. A further contributory factor is that in the latter, the distance from the axis of the centroid is part of the overall equation, whereas in the former the distance from the axis of the centroid does not enter into the equation. However, a ship is not a rectangular block in plan view, but a diamond or lozenge shape. Taking this as the best fit shape, the block coefficient is not 1 but 0.5. The radius of gyration of the new shape is now one third that of the full box shape. Since the radius of gyration is part of the equation which gave a one third reduction in force required to decelerate the box shape, then it follows that with a block coefficient of 0.5, the reductions is now one ninth. But the mass has now been halved, so the factor of 9 must also be halved, giving a final figure of 4 1/2. Thus for a block coefficient of 0.5 the reduction factor is 4 1/2, whilst for a block coefficient of 1, it is 3. The ship shape lies somewhere between these two and can be assumed to be equal to 7/2. Instituting a turn at the point where the anchor is let go will change the force on the cable from one of axial translation to one of rotational translation. But one of the factors of rotational inertia is the distance from the axis through the centroid. By using the anchor and cable this distance has now been increased by the length of the cable, a factor of 6.5. By applying the two factors [7/2 X 13/2J one finds the force on the cable is approximately 23 times less than the original case l Clearly, keeping the cable at right angles to the hull greatly reduces the likelihood of extreme forces being applied to the anchoring equipment which is why the U-turn method is very much safer and is associated with far fewer accidents. When the cable is at 90 degrees to the fore and aft line, fore and aft movement does not affect the tension of the cable, or only minimally. In this way, it is very difficult to exceed the forces that one is trying so hard to avoid with the fore and aft method. This technique is also more forgiving should the master have misjudged the speed and is moving too fast and especially in the event of engine failure during the anchoring procedure. This is quite impossible using the traditional, fore and aft method. Having the skill to anchor a vessel which is moving is one that can save the ship, possibly your life and your job!

17

VI DEOTEL PRODU CTI ONS ANCHORING SAFELY

USING THE U-TURN METHOD The anchor and gear is prepared as for any normaL anchoring. The windLass is tested in both directions, the Locker checked for obstructions, the dog clutch engaged, the anchor walked out clear of the hawsepipe, brake on, bow stopper/compressor on and clutch out. The master shouLd always take personal responsibility for these checks.

6.1 OPERATIONAL BRIEFING Before the anchor is to be let go, there need to be two pre-operational briefings. The first briefing is a training session to ensure that the personnel concerned know exactly how the equipment works and should be used. The second briefing is just before anchoring, to ensure that the crew understands that : SECOND BRIEFING :

• On large ships there should ideally be two men on the brake since the rated force cannot be applied by one man alone. • The anchor will be lowered under power to an ordered number of shackles on deck, say two, prior to taking out of gear and letting go . on the brake. • When the cable is released, the cable will be let out in a controlled manner so that each !.ink can be followed with the eye. • The cable is kept running out until the desired length is all out, which avoids the brake fade caused by the more common practice of stopping and starting. • When the cable is out at the desired length, the cable is stopped from moving by the brake then the bow stopper is put on. The safe pin is fully engaged whilst the cable is stopped and still vertically up and down . • When the bow stopper is on, the bridge is to be kept informed of the direction of the lead on the cable which must be kept on the beam until all movement has ceased . Only then can the cable be allowed to draw slowly ahead . If the bottom is known to be very deep, or particularly rocky , it would be prudent to walk the anchor out until just clear of the seabed.

18

VIDEOTEL PRODUCTIONS ANCHORING SAFELY

TIDE AND WIND Approach downwind/tide w ith minimum steerage way of 2-3 knots.

J,

U

J,

Hard a·starboard. Dead slow ahead.

J,

Only sideways drift Let go starboard anchor

Allow full scope to pay out in one controlled movement. Appty bra ke and compressor Short bursts of ahead or as te rn power to keep the lead as near perpendicular to the forecastle as is possible .

a." r

135 0 off course, all forward

~- ~o '''''' 5
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