Draft Survey Manual

DRAFT SURVEY

by Dirk Rombaut

DECEMBER 2003 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, or by any information storage and retrieval system, without prior written permission of the Société Générale de Surveillance S.A.

Preface It is internationally accepted in bulk trading that cargo measurement by draft survey is the most convenient and economical way of establishing the weight of cargo loaded on board a vessel. However, many operators in the industry consider draft measurement as a doubtful practice in which the cunning of the surveyor is more important than his professional expertise and experience. As it often happens, this conviction is both right and wrong at the same time. In fact, in many parts of the world, including some "industrialized" countries, this technique is still surprisingly empirical and based on local habits. In such cases, cargo measurement by draft survey ends up in a fish-market type of negotiation between the surveyor on one side and the ship's officers on the other. Yet, increasing value of raw materials commands a more professional approach. Following this trend SGS recognizes the need of experienced and competent draft surveyors. Experience has shown that draft surveys can be carried out by non-seafaring people provided they have been properly instructed in both theory and practice. To support this instruction, a need developed within SGS for an adequate training manual. It should be evident that if cargo is measured by SGS affiliates at both loading port and discharge port, it is of the utmost importance that the draft survey procedures used are the same. In an attempt to standardize procedures within SGS, the first comprehensive draft survey manual was written in 1967 by SMES (Rotterdam). However, this was designed for ex-captains of seagoing vessels and somewhat difficult for non-specialists to understand. Today, the Draft Survey Manual, prepared by SGS Belgium, is a modern, readily understandable document. This manual, when properly digested and applied, will contribute to enhance the professionalism of our Marine Services and to change some of the unfavourable opinions which are still delaying proper application of cargo measurement by draft survey. No attempt should be made to read the manual from beginning to end. This would be a rather discouraging task. Each section should be read and fully understood before moving on to the next. For the benefit of those studying the subject for the first time, the manual explains the basic principles of draft survey procedures. For those who have no seafaring experience, certain aspects are explained in greater detail than might otherwise be necessary. Furthermore bearing in mind that the manual may be used by SGS representatives whose first language is not English - it has been written in a clear and uncomplicated way. It includes an explanation of technical terms with translations from English into French, German and Spanish. Draft survey will involve the surveyor in the measurement of a variety of vessels of different types and nationalities - each with its own characteristics. The high level of accuracy required depends on careful attention to detail and the proper handling of unusual circumstances which may arise from time to time. Here, there is no substitute for proper practical training and experience - the mere study of this manual is not enough. It seems probable that in the years to come various additional corrections and new forms of measurement apparatus may be developed and this manual will therefore need to be revised from time to time in order to keep abreast of modern practice. Suggestions for improving this manual are welcome and can be sent to the author, Dirk Rombaut, at SGS Belgium, Antwerp.

1

Table of Contents 1

GLOSSARY OF TERMS - ENGLISH

2

GLOSSARY OF TERMS - FRENCH

3

GLOSSARY OF TERMS - GERMAN

4

GLOSSARY OF TERMS - SPANISH

5

INTRODUCTION TO DRAFT SURVEY

6

READING OR MEASURING THE DRAFT 6.1 Introduction 6.2 Reading the draft 6.3 Measuring the draft 6.4 Calculation of the mean drafts fwd, aft and midships 6.5 Exercise m/v Mindiv

7

PERPENDICULAR CORRECTION 7.1 Introduction 7.2 Position of the draft marks 7.3 Principle of perpendicular correction 7.4 Formula 7.5 Exercise m/v Mindiv

8

CORRECTION FOR HULL DEFLECTION 8.1 Introduction 8.2 Types of deformation 8.3 Factors which can influence the deflection 8.4 Formula 8.5 Exercise m/v Mindiv

9

CALCULATION OF THE CORRESPONDING DISPLACEMENT 9.1 Introduction 9.2 Definitions 9.3 Hydrostatic particulars 9.4 Exercise m/v Mindiv

10

CORRECTING THE DISPLACEMENT FOR TRIM AND LIST 10.1 Introduction 10.2 Definitions 10.3 Principle of trim correction 10.4 First Trim Correction (FTC) 10.5 Second Trim Correction (STC) 10.6 Total Trim Correction (TTC) 10.7 Displacement corrected for trim 10.8 List correction 10.9 Exercise m/v Mindiv

2

Table of Contents 11

CORRECTING THE DISPLACEMENT FOR DENSITY 11.1 Introduction 11.2 Definitions 11.3 Sampling of the surrounding water 11.4 Measuring the density 11.5 Displacement corrected for density 11.6 Exercise m/v Mindiv

12

DETERMINATION OF THE DEDUCTIBLE LIQUIDS 12.1 Introduction 12.2 Definitions 12.3 Ballast water 12.4 Fresh water 12.5 Bunkers 12.6 Net displacement 12.7 Other items 12.8 Exercise m/v Mindiv

13

THE CARGO WEIGHT AND CONSTANT 13.1 The cargo weight 13.2 The constant 13.3 Exercise m/v Mindiv

3

Section 1: Glossary - English SECTION 1 GLOSSARY OF TERMS - ENGLISH

Term or abbreviation

Definition and explanation

aft

At or towards the rear part of the vessel.

aft draft

Draft, measured at the aft part of the vessel.

aft perpendicular

An imaginary vertical line, at right angles to the keel, passing through the first frame and therefore located on or nearby the ship's rudder post.

AP

Aft perpendicular.

after peak tank

A compartment situated at the extreme rear of the vessel often used to contain fresh water or ballast water.

ballast

Water pumped into or out of the vessel in order to maintain stability.

ballast tanks

Tanks aboard the vessel especially designed to receive ballast water or, in the case of tank vessels, cargo tanks used to contain ballast.

breadth

Maximum width of the ship.

boiler feed water tanks

Tanks provided aboard the vessel to contain water used for the production of steam.

bilges

Spaces at the bottom of the engine room or pump rooms where water is allowed to accumulate. As the bilges usually also contain waste oil, they may not be discharged within the port limits. For draft survey purposes, the quantity of liquid in the bilges should be controlled before and after loading or discharge, so that any change in quantity can be detected.

bunker tanks

Tanks intended to contain fuel oil either for steam raising purposes or for the provision of power to the main engines and auxiliaries.

calibration tables

See tank sounding tables

centre of flotation

The point around which a ship tips often called the "tipping centre".

4

Section 1: Glossary - English cofferdams fwd and aft

These terms apply more particularly to ocean tankers, coastal tankers and tank barges. They are empty spaces provided in order to separate the cargo tanks from the machinery space aft, from the forward peak, and other forward parts of the ship. Cofferdams frequently contain water, either intentionally or accidentally, and should therefore always be sounded both before and after cargo is measured by draft survey.

constant

The difference between the light ship weight according to ship's documents and the net empty survey displacement after deducting all measurable weights.

deadweight

This is the weight of a vessel's cargo, fuel, water and stores.

deck line

A line clearly marked on the port and starboard sides of the vessel, amidships as required by International Load line Regulations.

deep tanks

Tanks situated near to the bottom of the vessel.

density (true)

The mass of a volume unit of a liquid. It may be expressed in terms of grams per millilitre, kilograms per cubic meter, pounds per cubic foots, etc.

density (apparent)

Density, as defined above, but without allowing for the buoyancy effect of the atmosphere. The apparent density of seawater, fresh water, ballast water, etc. is measured by the SGS draft survey hydrometer. This gives weights comparable to those that would be obtained by weighing a carefully calibrated container on an accurate weighbridge to obtain commercial weights.

diesel oil

Fuel oil used to feed diesel engines. There are various grades of diesel oil including light diesel oil for auxiliary engines and heavier diesel oil for main engines.

displacement

The total weight of water displaced by the vessel. Displacement includes the light ship weight and all other weights on board including cargo, ballast bunkers, etc.

displacement table/scale

A table, especially prepared for each vessel, giving the displacement corresponding to various drafts.

double bottom tanks

Tanks situated in the vessel's double bottom and used either for bunkers or ballast water.

5

Section 1: Glossary - English draft (draught)

Depth of water from the water surface down to the bottom of the ship's keel.

draft marks

A series of figures painted or welded on the vessel's hull, usually forward, midships and aft, on both port and starboard sides and indicating the draft of the vessel at the points where the draft marks are situated.

draft survey

A system of cargo measurement based on measuring the draft of the vessel before and after loading or discharge, taking into account any changes in weight other than cargo, which may have taken place during cargo handling operation, i.e. changes in the weight of water ballast, bunkers, stores, etc.

drinkable water

Fresh water for human consumption.

engine water

Water used for the cooling of diesel engines.

even keel

When the forward and aft drafts of a vessel are identical, the ship is said to be on an 'even keel'.

fore (forward)

At or towards the front part of the vessel.

forward draft

Draft, measured at the forward part of the vessel.

forepeak tank

A compartment situated at the extreme forward part of the vessel often used to contain ballast water.

forward perpendicular

An imaginary vertical line, at right angles to the keel and passing through the point where the summer load line intersects the vessel's stem.

FP

Forward perpendicular.

free board

Distance between the upper part of the deck line and the water level.

freeboard (assigned or statutory)

The distance from the upper part of the deck line to the summer load line as 'assigned' or stated in the Freeboard Certificate relating to the vessel concerned.

fresh water

Not salt water (sea water). This is the water on board a vessel for drinking, washing, etc.

fuel oil (heavy)

High density fuel oil used either as boiler fuel or as fuel for main diesel engines suitably adapted for the purpose.

6

Section 1: Glossary - English hogging

The deflection of a vessel loaded in such manner that the draft amidships is less than the mean of the forward and aft drafts.

hydrostatic curves

A document especially prepared for each vessel indicating, among other things, the centre of flotation or 'tipping centre' at various drafts.

keel

The part of a ship extending along the bottom from stem to stern.

LCF

Longitudinal centre of flotation.

length between

Distance between the forward and aft perpendiculars

perpendiculars (LBP)

measured parallel to the keel.

list

Inclination of the vessel from the vertical position measured at the longitudinal midships axis. It is usually measured by means of an inclinometer giving results in degrees of angle. List can also be calculated, if necessary, from the difference between the port and starboard midships drafts.

light ship weight

The weight of the vessel after completion of construction but without fuel bunkers, stores, etc. The light ship weight is usually mentioned on the vessel's displacement scales and represents the difference between the displacement scale and the deadweight scale.

lubricants

Oils for lubricating the main engine, auxiliary engines and other moving equipment aboard the vessel.

mean aft draft

Average of the aft drafts on port and starboard sides.

mean forward draft

Average of the midships drafts on port and starboard sides.

mean midships draft

Average of the midships drafts on port and starboard sides.

midships

Longitudinal centre of the vessel as indicated on the hull by the Port and Starboard load line marks.

7

Section 1: Glossary - English moment

The moment of a force is a measure of the rotating effect of the force about a given point. The rotating effect will depend upon the magnitude of the force and the length of the lever upon which the force acts, i.e., the perpendicular distance between the line of action of the force and the point around which the moment is being exerted.

Moment to change trim 1 cm (MTC)

The force required to change the trim of a vessel by 1 cm. This is defined as the weight - in metric tons, multiplied the distance it is moved from the centre of flotation - in meters.

Moment to change trim 1 inch (MTI)

The force required to change the trim of a vessel by 1 inch. This is defined as the weight - in long tons, multiplied the distance it is moved from the centre of flotation - in feet.

Plimsoll line

Another name for summer load mark.

port side

The left-hand side of the vessel as seen by an observer facing forward.

rudder post

The vertical axis around which the rudder turns.

sagging

The deflection of a vessel loaded in such manner that the draft amidships is greater than the mean of the forward and aft drafts.

scale drawings

Vessel's plans prepared so that each centimetre of distance on the scale corresponds to a known distance on the vessel. For example, a scale marked 1/100 means that 1 cm on the drawing corresponds to 1 m on the ship itself.

sounding

Distance between the bottom of a tank and the surface of the liquid which it contains.

sounding pipe

A fixed pipe through which soundings are taken.

sounding tables

Calibration tables giving volumes corresponding to liquid heights.

specific gravity

Ratio between the mass or weight in air of a given volume of liquid and the mass or weight in air of the same volume of distilled water. Both the temperature of the liquid and the temperature of the water must be defined. There are thus various forms of specific gravity which can lead to considerable confusion. It is for this reason that the term apparent density is preferred, as this corresponds to weights obtained by weighing on a weighbridge.

8

Section 1: Glossary - English starboard side

The right-hand side of the vessel as seen by an observer facing forward.

stem correction

Correction applied to the mean forward draft when the forward draft marks are not situated at the forward perpendicular.

stern correction

Correction applied to the mean aft draft when the aft draft marks are not situated at the aft perpendicular.

summer load line

An imaginary line, parallel to the keel passing through the upper edge of the summer mark which corresponds to the maximum draft permitted in the summer zone in sea water.

summer mark

The line, surrounded by a circle, permanently marked by centre punch, or by welding, on the port and starboard sides of the vessel amidships as prescribed by the ship's load line certificate.

t per cm immersion (TPC)

The number of metric tons required to change the mean draft of the vessel by 1 cm.

t per inch immersion (TPI)

The number of long tons required to change the mean draft of the vessel by 1 inch.

trim

Difference between the mean draft forward and the mean draft aft, both measurements having been corrected to the forward and aft perpendiculars where necessary.

trim corrections

Corrections applied to the displacement of the vessel when the vessel is not floating on an even keel.

ullage

Distance between the surface of the liquid in a tank and the top of the tank or corresponding sounding pipe.

9

Section 2: Glossary - French SECTION 2 GLOSSARY OF TERMS - FRENCH

Terme anglais/français

Définition et explication

aft/arrière

A ou vers l'arrière du navire.

aft draft/enfoncement arrière

Enfoncement mesuré à l'arrière du navire.

aft perpendicular/ perpendiculaire arrière

Ligne verticale imaginaire, perpendiculaire à la quille, passant par la première membrure et passant par conséquent sur ou proche de l'axe du gouvernail.

AP

Aft perpendicular.

after peak tank/ compartiment de poupe

Compartiment situé à l'extrémité arrière du navire souvent utilisé pour recevoir de l'eau douce ou du ballast.

ballast/ ballast, lest

Eau de rivière ou de mer, pompée ou refoulée par le navire de façon à ajuster l'assiette et/ou l'enfoncement du navire.

ballast tanks/ compartiments à ballast

Compartiments prévus spécialement pour recevoir le ballast ou, dans le cas de navires citerne, compartiments prévus pour contenir la marchandise, mais aussi utilisés pour le ballast.

breadth/largeur

Largeur maximale du navire.

boiler feed water tanks/ compartiments pour l'eau des chaudières

Réservoirs du navire qui contiennent l'eau utilisée pour la production de vapeur.

bilges/ fonds de cale

Emplacements au fond de la salle des machines ou des pompes où l'eau peut s'accumuler. Du fait que les fonds de cale contiennent également de l'huile usagée, ils ne doivent pas être vidés dans l'enceinte portuaire. En matière de jaugeage, les fonds de cale doivent être contrôlés avant et après chargement afin de prendre en compte tout changement quantitatif.

10

Section 2: Glossary - French bunker tanks/ compartiments pour hydrocarbures de soute

Compartiments conçus pour recevoir le combustible lourd (fuel-oil) pour la production de vapeur et pour la propulsion des moteurs principaux et auxiliaires.

bow/proue

Voir stem.

calibration tables/ tables d'épalement

Tables donnant pour chaque compartiment ou réservoir le volume correspondant à la hauteur de liquide (sounding) ou à la hauteur libre (ullage).

centre de flottaison

Point autour duquel le navire oscille, souvent appelé "point de bascule".

cofferdams fore and aft/ batardeaux avant et arrière

Ce terme s'applique plus particulièrement aux navires citerne de haute mer, côtiers et aux péniches citerne. Ce sont des caissons creux conçus pour séparer la citerne contenant la marchandise, d'une part de la chambre des machines et, d'autre part, du compartiment avant ou de la partie avant de l'embarcation à l'avant.

constant/ constante

Différence entre le poids à vide du navire indiqué sur les documents du navire et le déplacement net à vide après déduction de tous les poids mesurables.

deadweight/ poids lourd

Différence entre le poids à vide du navire et celui du navire en charge. Cela inclut le poids du chargement, des combustibles, de l'eau et de la constante.

deck line/ ligne de pont

Une ligne clairement marquée sur les côtés babord et tribord au milieu du navire, au niveau de pont, comme requis par l'International Loadline Regulation.

deep tanks/ compartiments de cale

Compartiments situés près du fond du navire.

density (true)/ densité (vraie)

Masse (dans le vide) d'une unité de volume d'un liquide. On peut l'exprimer en grammes par millilitre, kilogrammes par mètre cube, livres par pied cube, etc.

11

Section 2: Glossary - French density (apparent)/ densité apparente

Densité, comme définie ci-dessus, mais exprimée en termes de masse apparente dans l'air, c'est-à-dire sans correction pour la poussée exercée par l'air sur l'eau et sur les poids normalement employés dans le commerce. La densité apparente de l'eau de mer, de l'eau douce, du ballast, etc. est mesurée par le densimètre SGS et permet d'obtenir des poids comparables à ceux que l'on obtiendrait en pesant un conteneur soigneusement calibré sur un pont à bascule précis, de façon à obtenir des poids commerciaux.

diesel oil/ diesel

Combustible pour les moteurs diesel. Il y a plusieurs types de diesel, depuis le diesel léger pour les moteurs auxiliaires jusqu'au diesel lourd utilisé pour les moteurs principaux.

displacement/ déplacement

Poids total du volume d'eau déplacé par la coque du navire; sont inclus le poids à vide du navire et tous les autres poids à bord, y compris le chargement, le ballast, les hydrocarbures de soute, etc.

displacement table/ table de déplacement

Une table spécialement préparée pour chaque navire donnant le déplacement correspondant aux divers enfoncements.

double bottom tanks/ compartiments de double fond

Compartiments situés dans le double fond du navire, utilisés pour contenir soit du ballast, soit des hydrocarbures.

draft (draught)/ enfoncement

Hauteur d'eau entre la surface de l'eau et le bas de la quille du navire.

draft marks/ marques d'enfoncement

Série de chiffres peints ou soudés sur la coque, (à l'avant, au milieu et à l'arrière du navire, à babord et à tribord), qui indiquent l'enfoncement du navire aux endroits où ces marques sont situées.

12

Section 2: Glossary - French draft survey/ jaugeage

Système de détermination du poids d'une cargaison basé sur la mesure de l'enfoncement d'un navire avant et après chargement ou déchargement, prenant en considération toutes les variations du poids autres que celles dues à la marchandise, qui peuvent survenir pendant la manutention de la marchandise, c'est-à-dire les variations du poids du ballast, des hydrocarbures de soute, de la constante, etc.

drinkable water/eau potable

Eau potable pour l'équipage.

engine water/eau pour le moteur

Eau de refroidissement des moteurs diesel.

even keel/ quille "horizontale"

Lorsque les enfoncements avant et arrière sont identiques, on dit que le navire a sa quille "horizontale".

fore (forward)/avant

A ou vers l'avant du navire.

forward draft/ enfoncement avant

Enfoncement mesuré à l'avant du navire.

fore peak tank/ compartiment de proue

Compartiment situé à l'extrémité avant du navire, souvent utilisé pour recevoir le ballast.

forward perpendicular/ perpendiculaire avant

Ligne imaginaire verticale, perpendiculaire à la quille qui passe par le point d'intersection entre la ligne d'été et la ligne de proue.

FP

Forward perpendicular.

freeboard/ hauteur libre

Distance variable entre le haut de la ligne de pont et la ligne de flottaison.

freeboard (assigned or statutory)/ hauteur libre officielle

Distance fixe entre le haut de la ligne de pont et la ligne d'été officielle figurant sur le "certificat de hauteur libre" du navire concerné.

fresh water/ eau douce

Pour la mesure des liquides déductibles d'un jaugeage, c'est la somme de l'eau potable et de l'eau (douce) non potable qui est prise en compte.

fuel oil (heavy)/ combustible lourd

Combustible lourd utilisé pour les chaudières ou le moteur principal et spécialement adapté à cet usage.

13

Section 2: Glossary - French hogging/ cambrure

Déformation du fond d'un navire telle que l'enfoncement au milieu du navire est plus petit que la moyenne des enfoncements avant et arrière.

hydrostatic curves/ coubres hydrostatiques

Document propre à chaque navire qui indique entre autres, la position du centre de flottaison en fonction de l'enfoncement.

keel/quille

Partie inférieure axiale de la coque du navire.

LCF

Le centre longitudinal de flottaison.

length between perpendiculars (LBP)/ longueur entre les perpendiculaires

Distance entre les perpendiculaires avant et arrière parallèlement à la quille.

list/ bande, gite, assiette latérale

Inclinaison du navire par rapport à la position verticale mesurée au niveau de l'axe longitudinal au milieu du navire. La bande est normalement mesurée à l'aide d'un inclinomètre donnant des résultats en degrés d'angle. La bande peut aussi être calculée, si nécessaire, par la différence entre les enfoncements babord et tribord au milieu du navire.

light ship weight/ poids à vide du navire

Poids du navire après construction mais sans combustible, approvisionnements de bord, etc. Le poids à vide du navire est normalement indiqué sur les tables de déplacement du navire et représente la différence (pour un enfoncement donné) entre les échelles de déplacement et de "poids lourd".

lubricants/ lubrifiants

Huiles pour lubrifier le moteur principal, les moteurs auxiliaires et autres équipements mobiles du navire.

mean aft draft/ enfoncement arrière moyen

Moyenne des enfoncements arrière, babord et tribord.

mean forward draft/ enfoncement avant moyen

Moyenne des enfoncements avant, babord et tribord.

mean midships draft/ enfoncement moyen au milieu du navire

Moyenne des enfoncements babord et tribord mesurés au milieu du navire.

14

Section 2: Glossary - French midships/ milieu du navire

Centre longitudinal du navire indiqué sur la coque par les marques d'été babord et tribord.

moment/ moment

Le moment d'une force est la mesure de l'effet de rotation de cette force autour d'un point donné. Cet effet dépend de la grandeur de la force et de la longueur du levier sur lequel la force s'exerce, c'est-à-dire la distance perpendiculaire entre la ligne d'action de la force et le point autour duquel le moment s'exerce.

moment to change trim 1 cm/ moment pour changer l'assiette de 1 cm.

Force en tonnes métriques multipliée par la distance en mètres nécessaire pour changer l'assiette du navire de 1 cm.

MTC

Moment to change trim 1 cm.

Plimsoll line/ligne Plimsoll

Autre nom pour la ligne d'été.

port side/ babord

Partie gauche du navire pour un observateur placé sur le navire et regardant l'avant.

rudder post/axe du gouvernail

Axe vertical autour duquel pivote le gouvernail.

sagging/ flexion

Déformation du fond d'un navire telle que l'enfoncement au milieu du navire est plus grand que la moyenne des enfoncements avant et arrière.

scale drawing/ plan à échelle

Plan du navire préparé de telle sorte que toute dimension en cm sur le plan corresponde à une dimension connue sur le navire. Par exemple, une échelle de 1/100 signifie que 1 cm sur le plan correspond à 1 m sur le navire lui-même.

sounding/ hauteur de liquide

Hauteur entre le fond d'un réservoir et la surface du liquide qu'il contient.

sounding pipe/ tuyau de sonde

Tuyau fixe au travers duquel on mesure la hauteur de liquide dans un réservoir.

sounding tables/ tables de sonde

Voir calibrations tables.

15

Section 2: Glossary - French specific gravity/ poids spécifique

Rapport entre le poids dans l'air d'un volume donné de liquide et le poids du même volume d'eau distillée. Les températures du liquide et de l'eau doivent être définies. Il y a donc plusieurs formes de poids spécifiques, ce qui peut entraîner d'importantes confusions. Pour cette raison, on préfère utiliser le terme "densité apparente" qui correspond à des poids obtenus par pesage sur pont bascule.

starboard side/ tribord

Partie droite d'un navire pour un observateur placé sur le navire et regardant vers l'avant.

stem correction/ correction avant

Correction appliquée à l'enfoncement moyen avant lorsque les échelles d'enfoncement avant babord et tribord ne sont pas situées sur la perpendiculaire avant.

stern correction/ correction arrière

Correction appliquée à l'enfoncement moyen arrière lorsque les échelles d'enfoncement arrière babord et tribord ne sont pas situées sur la perpendiculaire arrière.

summer load line or summer line/ ligne d'été

Ligne imaginaire, parallèle à la quille, passant par le bord supérieur de la marque d'été, qui correspond à l'enfoncement maximum autorisé dans la zone "été" en eau de mer.

summer mark/ marque d'été

Ligne entourée d'un cercle, marquée de façon permanente par poinçonnage ou soudure, sur les côtés babord et tribord au milieu du navire, conformément aux prescriptions du "Loadline Certificate" du navire.

t per cm(TPC)/ t par cm

Nombre de tonnes métrique nécessaires pour changer l'enfoncement moyen du navire d'un centimètre.

trim/ assiette longitudinale

Différence entre les enfoncements moyens avant et arrière, après corrections avant et arrière éventuelles.

trim corrections/ corrections d'assiette

Corrections appliquées au déplacement lorsque le bateau n'a pas sa quille horizontale.

ullage/ hauteur libre

Hauteur entre la surface du liquide et le haut du réservoir ou du tuyau de sonde correspondant.

16

Section 3: Glossary - German SECTION 3 GLOSSARY OF TERMS - GERMAN

Term or abbreviation

Definition and explanation

aft

Hinten oder in Richtung des hinteren Teiles des Schiffes.

aft draft

Tiefgang, gemessen bzw, abgelesen am Hinterschiff.

aft perpendicular

Eine imaginäre Linie, die im rechten Winkel zum Kiel durch die Mitte order entland des hinteren Endes des Ruderpfostens verläuft.

AP

Hinteres Lot.

after peak

Eine Abteilung im hinteren Ende des Schiffes, welche meistens zur Aufnahme von Ballastwasser oder auch Frischwasser benutzt wird.

ballast

Wasser, Hafen-/Fluss- oder Seewasser, welches in das Schiff eingelassen oder ausgepumpt wird, um den Tiefgang oder den Trimm des Schiffes zu verändern.

ballast tanks

Tanks speziell dafür ausgelegt, um Ballastwasser aufzunehmen oder im Falle von Tankschiffen und Ladungstanks, die auch zur Augnahme von Ballastwasser dienen.

breadth

Grösste Breite des Schiffes.

breadth moulded

Breite des Schiffes auf Spanten, also die Breite ohne Aussenhaut.

boiler feed water tanks

Tanks an Bord des Schiffes vorgesehen für die Aufnahme von Wasser für die Damferzeugung.

17

Section 3: Glossary - German bilges

Abteilungen am Boden des Maschinenraumes oder Pumpraumes, in denen sich Wasser und/oder Öl sammeln kann; da die Bilgen allgemein auch Schmutzöl beinhalten, dürfen sie nicht innerhalb der Hafengrenzen ausgepumpt werden; für Draft Survey-Zwecke sollte die Flüssigkeitsmenge vor und nach Beladung oder Entleerung des Schiffes kontrolliert werden, so dass jede Änderung der Menge festgestellt werden kann.

bunker tanks

Tanks, die entweder Öl für die Dampferzeugung oder den Antrieb der Hauptmaschinen und Hilfsmaschinen aufnehmen.

calibration tables

Siehe Tank-Peil-Tafeln: tank sounding tables.

centre of flotation

Der Auftriebzentrum ist der Schwerpunkt vom unbeladenen Schiff und wird auch Kippmoment gennannt.

cofferdams fwd and aft

Diese Bezeichnungen beziehen sich im besonderen auf Tankschiffe, Küstentanker und Tankleichter; es sind Leerräume, die dazu dienen, hinten-Ladungstanks vom Maschinenraum und vorne-Vorpiek und andere Teile zu trennen; Kofferdämme enthalten manchmal Wasser, beabsichtigt oder unbeabsichtigt, und sollten deshalb immer gepeilt werden bei Anfangs- und Endeiche.

constant

Ist die Differenz zwischen dem Leerschiffgewicht gemäss Schiffsunterlagen und der bereinigten/Netto-Verdrängung laut Schiffseiche nach Abzung aller feststellbaren Gewichte.

deadweight

Ist die Differenz zwischen dem Gewicht des leeren Schiffes (Leerschiffe-Gewicht) und dem Gewicht des Schiffes im abgeladenen Zustand; die Tragfähigkeit beinhaltet das Gewicht der Ladung, des Treibstoffes, des Wassers und der Ausrüstung.

deck line

Ein Strich deutlich markiert an der Backbord und Steuerbordseite in der Mitte des Schiffes gemäss "International Loadline Regulations".

deep tanks

Tanks, welche sich in der Nähe des Schiffbodens befinden.

density (true)

Die Masse einer Volumeeinheit einer Flüssigkeit; sie kann in Bezeichnungen von Gramm per Milliliter, Kilogram per Kubikmeter, engl. pounds per Kubifuss, etc. ausgedrückt werden.

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Section 3: Glossary - German density (apparent)

Dichte, wie oben definiert, jedoch ausgedrückt in der Bezeichnung "Masse in Luft", d.h. ohne Berücksichtigung des Luftauftriebes; die scheinbare Dichte des Seewassers, Frischwassers, Ballastwassers, usw. wird durch des SGS Draft Survey Hydrometer gemessen und gibt das Gewicht des Wassers an, welches vergleichbar ist mit dem Gewicht, was man erhält, wenn man einen volumenmässig sorgfältig vermessenen gefüllten Behälter auf einer genauen Waage wiegt, so wie man handelsübliche Gewichte feststellt.

diesel oil

Brennstoff zum Antrieb von Dieselmotoren; es gibt verschiedene Sorten von Dieselöl; einschliesslich leichtem Dieselöl für die Hilfsdiesel und schwerem Dieselöl für die Hauptmaschinen.

displacement

Das Gewicht des Wassers, welches durch das Gewicht des Schiffes verdrängt wird; die Verdrängung beinhaltet das Gewicht des leeren Schiffes (leerschiffgewicht) plus aller anderen Gewichte an Bord, einschliesslich Ladung, Ballast, Bunker, usw.

displacement table

Eine Tabelle speziell für jedes Schiffe erstellt, woraus die jeweilige Verdrängung zu dem entsprechenden Tiefgang zu entnehmen ist.

double bottom tanks

Tanks, welche sich im Doppleboden des Schiffes befinden und für die Aufnahmen von Ballastwasser oder Brennstoff bestimmet sind.

draft (draught)

Tiefe des Wassers von der Wasseroberfläche hinunter bis zum boden des Kieles.

draft marks

Eine Zahlenreihe auf dem Schiffsrumpf, aufgemalt oder aufgeschweisst, normalerweise vorne, mittschiffes und hinten auf beiden Seiten des Schiffes; sie gibt jeweils den Tiefgang des Schiffes dort an, wo sich diese Marken befinden.

draft survey

Eine Methode der Ladungs-Gewichts-Bestimmung, basierend auf der Ermittlung des Schiffstief-ganges vor und nach des Be- oder Entladung under Berücksichtigung aller Gewichtsveränderungen, die während der Ladungsarbeiten stattgefunden haben können, ausser den Veränderungen der Ladung, d.h. Gewichtsveränderungen beim Ballast-wasser, Brennstoff, Ausrüstung, usw.

drinkable water

Frischwasser für den menschlichen Verbrauch.

19

Section 3: Glossary - German engine water

Wasser zu Kühlungszwecken der Dieselmotoren.

even keel

Wenn die Tiefgänge vorn und hinten identisch sind, sagt man, das Schiff ist auf ebenen Kiel.

fore (forward)

Am oder in Richtung des vorderen Endes des Schiffes.

forward draft

Tiefgang am vorderen gemessen/abgelesen.

forepeak tank

Eine Abteilung im äusseren vorderen Ende des Schiffes, meistens benutzt zur Aufnahme von Frischwasser oder Ballastwasser.

forward perpendicular

Eine gedachte senkrechte Linie im rechten Winkel zum Kiel, die durch den Punkt führt, wo die SommerSeewasser-Tiefgangslinie den Vorsteven schneidet.

FP

Forward perpendicular - vorderes Lot.

freeboard

Distanz zwischen der Oberkante des Deckstriches und der Wasseroberfläche.

Teil

des

Schiffes

freeboard (assigned or staturory) Die Distanz zwischen der Oberkante des Deckstriches und der Sommer-Seewasser-Ladelinie ist der "assigned" oder angegebene Freibord, welcher für dieses Schiff im Freibordzeugnis festgelegt ist. fresh water

Für den Zweck des Draft Survey kann Frischwasser bei den deductable liquids als Gesamtmenge bestehend aus Trinkwasser und Waschwasser angesetzt werden.

fuel oil (heavy)

Schwer Öl, benutzt entweder als Brennstoff für Kessel oder Hauptmaschinen mit entsprechender Aufbereitung für diesen Zweck.

hogging

Die Verformung eines Schiffes, welches in der Weise beladen würde, dass der Tiefgang mittschiffs geringer ist als das Mittel aus dem vorderen plus hinteren Tiefgängen.

hydrostatic curves

Ein Dokument (Formkurvenblatt) für jedes Schiff erstellt, in dem sich u.a. eine Kurve befindet, von der das centre of flotation oder tipping centre (Wasserlinienschwerpunkt, Auftriebzentrum) mittels entsprechendem Tiefgang herausgenommen werden kann.

keel

Teil des Schiffes, der sich am Schiffsboden vom Vor- zum Hintersteven erstreckt.

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Section 3: Glossary - German LCF

Länge zwischen Auftriebzentrum und Mittschiff.

length between perpendicular (LBP)

Abstand zwischen vorderem und hinterem Lot parallel zum Kiel gemessen.

list

Neigung des Schiffes gegenüber der aufrechten Position gemessen an der Längsschiffs-Mittel-achse; sie wird gewöhnlich mittels eines Inklinometers (Neigungsmesser) gemessen, welches die Winkelgrade anzeigt; die Schlagseite kann auch aus der Tiefgangsdifferenz der Backbord- un Steuerbord-Mittschiffstiefgänge errechnet werden.

light ship weight

Das Gewicht des Schiffes nach Fertigstellung, aber ohne Brennstoffe, Ausrüstung, usw.; das Leer-Schiff-Gewicht wird gewöhnlich in der Verdrängungskala angegeben und ist die Gewichts-differenz aus den Angaben der Verdrängungskala und Tragfähigkeitskala.

lubricants

Oele zur Schmierung der Hauptmaschine, Hilfsmaschinen oder anderer beweglicher Teile an Bord des Schiffes.

mean aft draft

Das Mittel aus den Tiefgängen gemessen bzw. abgelesen auf Backbord- und Steuerbordseite des Hinterschiffes.

mean forward draft

Das Mittel aus den Tiefgängen gemessen bzw. abgelesen auf Backbord- und Steuerbordseite des Vorschiffes.

mean midships draft

Das Mittel aus den Tiefgängen gemessen bzw. abgelesen auf Backbord- und Steuerbordseite mittschiffs.

midships

Mitte der Längsschiffachse; wird am Schiff angezeigt durch die Backbord- und Steuerbord- lademarken.

moment

Das Moment einer Kraft ist das Mass für die Drehwirkung der Kraft um einen gegebenen Punkt; die Drehkraft hangt ab von der Grösse der Kraft und der Länge des Hebelarmes, auf den die Kraft einwirkt, d.h. die senkrechte oder waagerechte Entfernung zwischen dem Angriffspunkt der Kraft und dem Punkt, an dem sich das Moment auswirkt.

moment to change trim 1 cm

Die Kraft in metrischen Tonnen multipliziert mit der Entfernung in Metern, die benötigt wird, um den Trim des Schiffes um 1 cm zu ändern.

MTC

Trimmoment für 1 Einheitstrimmoment - ETM.

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cm

Trimmänderung.

Section 3: Glossary - German Plimsoll line

Andere Bezeichnung für Seewasser-Sommer-Marke.

port side

Linke Seite des Schiffes bei Blickrichtung zum Vorderteil des Schiffes.

rudder post

Die vertikale Achse, um die sich das Ruder dreht.

sagging

Die Verformung eines Schiffes, welches in der Weise beladen wurde, dass der Mittschiffs-Tiefgang grösser ist als das Mittel aus vorderem plus hinteren Tiefgang.

scale drawings

Schiffspläne derart gezeichnet, dass jeder Zentimeter des Masstabes einer bestimmten Entfernung auf dem Schiff entspricht, z.B. ein Massstab 1/100 heisst 1 cm im Plan bedeutet 1 m auf dem Schiff.

sounding

Entfernung zwischen dem Boden des Tanks und der Oberfläche der Flüssigkeit, die sich im Tank befindet.

sounding pipe

Ein festinstalliertes Rohr, vorgenommen werden.

sounding tables

Masstabellen, die die Volumen der entsprechenden Flüssigkeitshöhen der einzelnen Tanks angeben.

specific gravity

Verhältnis zwischen der Masse oder dem Gewicht in Luft eines gegebenen Volumens einer Flüssigkeit und der Masse oder dem Gewicht in Luft desselben Volumens destillierten Wassers; beide Temperaturen für Flüssigkeit und destilliertes Wasser müssen dazu angegeben werden; es gibt deswegen die verschiedensten Angaben von "specific gravities", welche zu erheblichen Verwirrungen führen können; aus diesem Grunde wird die Bezeichnung "apparent density" vorgezogen, weil nur durch sie Gewichte ermittelt werden, die man auch bei der Gewichtsermittlung auf einer Waage erhält.

starboard side

Die rechte Siete des Schiffes bei Blickrichtung zum Vorderteil des Schiffes.

stem correction

Berichtigung des gemittelten vorderen Tiefganges, wenn die vorderen Tiefgänge (Backbord und Steuerbord) sich nicht am vorderen Lot befinden.

stern correction

Berichtigung des gemittelten hinteren Tiefganges, wenn die hinteren Tiefgänge (Backbord und Steuerbord) sich nicht am hinteren Lot befinden.

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durch

das

Peilungen

Section 3: Glossary - German summer load line

Eine angenommene Linie parallel zum Keil, welche durch die Oberkante der Sommer-Marke verlaüft und welche dem Maximum-Tiefgang in Seewasser innerhalb der Sommerzone entspricht.

summer mark

Die Linie, die mit einem Kreis eingefasst ist und mittels Körnung oder Schweissnaht dauerhaft fixiert ist auf der halben Schiffslänge an Backbord- und Steuerbordseite des Schiffes, wie im Freibord-Zeugnis vorgeschrieben.

t per cm (TPC)

Die Anzahl der metrischen Tonnen, die die Veränderung des Mitteltiefganges um einen Zentimeter hervorruft.

trim

Differenz zwischen gemitteltem vorderen gemitteltem hinteren Tiefgang, nachdem, wenn notwendig, beide Tiefgänge auf die Lote korrigiert wurden.

trim corrections

Berichtigungen zur Verdrängung des Schiffes, wenn das Schiffe nicht auf ebenem Kiel schwimmt.

ullage

Entfernung zwischen Oberfläche des Flüssigkeit in einem Tank und der Oberkante des Tanks bzw. des Peilrohres.

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Section 4: Glossary - Spanish SECTION 4 GLOSSARY OF TERMS - SPANISH

Término inglès/español

Definición y explicación

aft/ popa

En o hacia la parte posterior del barco.

aft draft/ calado de popa

Calado, medido en la parte de popa del barco.

aft perpendicular/ perpendicular de popa

Una línea vertical imaginaria, en ángulo recto a la quilla pasando por el centro o lado de popa del poste del timón del barco.

AP/ PP

Perpendicular de popa.

after peak tank/ tanque "peak" de popa

Un compartimento situado en el extremo posterior del barco utilizado frecuentemente para contener agua potable o agua de lastre.

ballast/ lastre

Agua, agua de rio o de mar, bombeada dentro o fuera del barco para ajustar el asiento o calado del barco.

ballast tanks/ tanques de lastre

Tanques diseñados especialmente en la parte interior del barco para recibir agua de lastre o, en el caso de los tanques del barco, tanques de carga utilizados para contener lastre. Anchura máxima del barco.

breadth / manga boiler feed water tanks/ tanque de alimentación de calderas

Tanques de abordo para contener agua utilizada para producir vapor.

bilges/ sentinas

Espacios en el fondo de la sala de máquinas o de bombas donde se puede acumular el agua. Dado que las sentinas normalmente también contienen aceites de desecho, no pueden ser descargadas dentro de los límites del puerto. A efectos de control por calados, la cantidad de líquido de las sentinas debe ser controlada antes y después de la carga o descarga para que no se produzca ningún cambio en la cantidad.

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Section 4: Glossary - Spanish bunker tanks/ tanques de combustibles

Tanques para contener fuel oil, ya sea para la subida del vapor o para proveer de fuerza a las máquinas principales y auxiliares.

calibration tables/ tablas de calibración

Ver tablas de sondeo de tanques.

centre of flotation/ centro de flotación

El punto sobre el cual un barco se equilibra, a menudo llamado el "centro de equilibrio".

cofferdams fwd and aft/ ataguias proa y popa

Estos términos se aplican especialmente a los buquetanques oceánicos, tanques costeros y tanques lancha. Son espacios vacios para separar los tanques de carga del lugar de máquinas de popa y del peak de proa y otras partes del barco. Los ataguias contienen frecuentemente agua, ya sea intencionada o accidentalmente, y por lo tanto deben ser siempre sondeados antes y después de que la carga esté siendo medida por control de calados.

constant/ constante

Diferencia entre el peso del barco en vacio de acuerdo a los documentos del mismo y el desplazamiento neto en vacio inspeccionado después de deducir todos los pesos medibles.

deadweight/ peso muerto

Diferencia entre el peso del barco en vacio y el barco cargado. Esto incluye la carga, el fuel, el agua y las provisiones.

deck line/ línea de cubierta

Línea claramente marcada a los lados de babor y estribor del barco, centrada como requieren las Regulaciones Internationales de Carga.

deep tanks/ tanques de profundidad

Tanques situados cerca del fondo de las sentias del barco.

density (true)/ densidad (real)

La masa de unidad de volumen de un liquido. Se puede expresar en términos de gramos por milímetro, kilogramos por metro cúbico, libras por pie cúbico, etc.

density (apparent)/ densidad (aparente)

Densidad como la arriba definida, pero expresada en términos de masa en aire, p.e. sin permitir el efecto de flotación de la atmósfera. La densidad aparente del agua de mar, agua potable, agua de lastre, etc. se mide con el hidrómetro de control por calados SGS, y dá pesos comparables a aquellos que se obtendrían pesando un contendor cuidadosamente calibrado en una básculapuente fiable, para obtener pesos comerciales.

25

Section 4: Glossary - Spanish diesel oil

Fuel oil utilizado para abastecer las máquinas diesel. Existen varios grados de diesel oil, incluyendo diesel oil ligero para máquinas auxiliares y diesel oil más pesado utilizado para las máquinas principales.

displacement/ desplazamiento

Peso total del agua desplazada por el barco. El desplazamiento incluye el peso del barco en vacio además de los otros pesos a bordo, incluyendo la carga, lastre, tanques, etc.

displacement table/ tabla de desplazamiento

Una tabla específicamente preparada para cada barco, que da el desplazamiento correspondiente a varios calados.

double bottom tanks/ tanques de doble fondo

Tanques situados en el doble fondo del barco y utilizados tanto para combustible como para agua de lastre.

draft (draught)/ calado

Profundidad del agua desde la superficie de esta hasta el fondo de la quilla del barco.

draft marks/ marcas de calado

Una serie de signos pintados o soldados en el casco del barco, normalmente en proa, centro y popa, en los lados babor y estribor, que indican el calado del barco en los puntos donde están situadas las marcas de calado.

draft survey/ supervisión del calado

Sistema de medida de la carga, basado en la medida del calado del barco antes y después de la carga o descarga, teniendo en cuenta cualquier cambio en el peso a parte de la carga, que pueda haber tenido lugar durante las operaciones de manipulación de la carga, p.e. cambios en el peso del agua de lastre, combustible, provisiones, etc.

drinkable water/ agua potable

Agua destinada al consumo humano.

engine water/ agua de máquina

Agua utilizada para los sistemas de refrigeración de las máquinas diesel.

even keel/ equilibrio de asientos

Cuando los calados de proa y popa de un barco son idénticos, se dice que el barco está en "equilibrio de asientos".

fore (forward)/ proa

En o hacía la parte frontal del barco.

forward draft/ calado de proa

Calado medido en la parte de proa del barco.

26

Section 4: Glossary - Spanish forepeak tank/ tanque "peak" de proa

Un compartimento situado en el extremo de la parte de proa del barco utilizado a menudo para contener agua potable o agua de lastre.

forward perpendicular/ perpendicular de proa

Una línea vertical imaginaria, en ángulo recto a la quilla pasando a través del punto donde la línea de carga de verano intersecciona el mastil del barco.

FP / PF

Perpendicular de proa.

freeboard/ altura borda

Distancia entre la parte superior de la línea de cubierta y la superficie del agua.

freeboard (assigned or statutory)/ altura borda (asignada o estatutoria)

La distancia desde la parte superior de la línea de cubierta a la línea de carga de verano como "asignada" o establecida en el Certificado de Altura Borda del barco concerniente.

fresh water/ agua potable

Para el propósito de control de medida de calado de los "líquidos deducibles", el agua potable se puede definir como el total de agua para beber y lavarse que hay a bordo del barco.

fuel oil (heavy)/ fuel oil (pesado)

Fuel oil de alta densidad utilizado ya sea como calentador o como fuel para las principales máquinas diesel, adecuadamente adaptado para el propósito.

hogging/ quebranto

Encorvadura de un barco cargado de tal manera que el calado de centro es menor que la media de los calados de popa y proa.

hydrostatic curves/ curvas hidrostáticas

Un documento especialmente preparado para cada barco, indicando, entre otras cosas, el centro de flotación o "centro de equilibrio" en varios calados.

keel/ quilla

Parte de un barco a lo largo del fondo desde proa a popa.

LCF

Distancia entre el centro de flotación y el centro del barco.

length between perpendiculars (LBP)/ longitud entre perpendiculares (LEP)

Distancia entre las perpendiculares de popa y proa medidas paralelamente a la quilla.

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Section 4: Glossary - Spanish list/ bandeo

Inclinación del barco desde la posición vertical medida en el eje longitudinal del centro. Se mide normalmente por medio de un inclinómetro que da los resultados en grados de ángulo. El bandeo se puede también calcular, si es necesario, por la diferencia entre los calados de centro de babor y estribor.

light ship weight/ peso del barco en vacío

El peso del barco después de terminada su construcción pero sin tanques de fuel, despensas, etc. El peso del barco en vacío se menciona normalmente en las gráficas de desplazamiento y representa la diferencia entre la gráfica de desplazamiento y la gráfica de peso muerto.

lubricants/ lubricantes

Aceites para lubricar la máquina principal, máquinas auxiliares y otros equipos de cinética en el exterior del barco.

mean aft draft/ calado medio de popa

Promedio de los calados medidos en los lados babor y estribor de popa del barco.

mean forward draft/ calado medio de proa

Promedio de los calados medidos en los lados babor y estribor de proa del barco.

mean midships draft/ calado medio de centro

Promedio de los calados medidos en los lados babor y estribor del centro del barco.

midships/ medio

Centro longitudinal del barco como se indica en el casco por las marcas de línea de carga de babor y estribor.

moment/ momento

El momento de una fuerza es la medida del efecto de rotación de dicha fuerza en un punto dado. El efecto de rotación dependerá de la magnitud de la fuerza y de la longitud del brazo sobre el que actúa, es decir la distancia perpendicular entre la línea de acción de la fuerza y el punto alrededor del cual se ejerce el momento.

moment to change trim 1cm/ momento de cambio del trimado 1 cm

Es la fuerza en toneladas métricas multiplicada por la distancia en metros requerida para cambiar el trimado del barco de 1 cm.

MTC

Momento para cambiar el trimado de 1 cm.

Plimsoll line/ línea Plimsoll

Otra manera de denominar a la línea de verano.

port side/ lado babor

Lado izquierdo del barco visto por un observador de cara a la proa.

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Section 4: Glossary - Spanish rudder post/ poste de timón

Eje vertical alrededor del cual gira el timón.

sagging/ arrufo

Encorvadura de un barco cargado de tal manera que los calados de centro son mayores que la media de los calados de popa y proa.

scale drawings/ planos

Son los planos del barco preparados de tal manera que cada centímetro de distancia en la escala corresponde a una distancia conocida en el barco, p.e. en la escala marcada como 1/100 significa que 1 cm de plano corresponde a 1 m de la estructura del barco.

sounding/ sondeo

Distancia entre el fondo de un tanque y la superficie del líquido que contiene.

sounding pipe/ sonda

Tubo fijo a través del cual se hace el sondeo.

sounding tables/ tablas de sondeo

Son tablas de calibración que dan los volumenes correspondientes a los pesos de los líquidos contenidos.

specific gravity/ gravedad específica

Es la relación entre la masa o peso en aire de un volumen dado de líquido y la masa o peso en aire del mismo volumen de agua destilada. La temperatura del líquido y la del agua deben ser definidas. Hay varias formas de gravedad específica que pueden conducir a considerable confusión. Es por esta razón que el término "densidad aparente" es preferible, ya que se corresponde con el peso obtenido pesando sobre una báscula puente.

starboard side/ lado estribor

El lado derecho del barco tal y como un observador lo vería de cara a proa.

stem correction/ corrección por stem

Es la corrección aplicada al promedio del calado de proa cuando los calados delanteros de babor y estribor no están situados en la perpendicular correspondiente.

stern correction/ corrección por stern

Es la corrección aplicada al promedio del calado de popa cuando los calados de popa lados babor y estribor no están situados en la perpendicular correspondiente.

summer load line/ línea de carga de verano

Línea imaginaria, paralela a la quilla del barco que pasa por el eje superior de la marca de verano y que corresponde al calado máximo transportado en una zona de verano en agua de mar.

29

Section 4: Glossary - Spanish summer mark/ marca de verano

Línea rodeada por un círculo prominentemente marcada en el centro por grabado o soldado a la plancha en los lados babor y estribor del barco tal y como prescribe el Certificado de Carga Máxima del barco.

t per cm (TPC)/ toneladas por cm

El número de toneladas métricas requeridas para cambiar el promedio del calado de un barco en 1 cm.

trim/ trimado

Es la diferencia existente entre el promedio del calado de proa y el promedio del calado de popa habiendo sido corregidas ambas medidas a la perpendicular de proa y popa cuando fuese necesario.

trim correction/ corrección por trimado

Son las correcciones aplicadas al desplazamiento de un barco cuando este no está flotando con la quilla plana, es decir, en equilibrio de calados.

ullage/ vacios

Distancia existente entre la superficie del líquido en un tanque y el tope de ese tanque o la correspondiente sonda.

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Section 5: Introduction SECTION 5 INTRODUCTION TO DRAFT SURVEY

5.1 General principles The first question we need to answer is “What is a draft survey?” Draft survey is an indirect weighing method which assesses the weight of a cargo loaded on board or discharged from a vessel. The method is based upon the principle of Archimedes which states the following: ‘A vessel, freely floating in water, will displace a weight of water equal to its own weight.’ and it is exactly the weight of this displaced water which is calculated by draft survey. In the following sections of this manual, details will be given regarding the procedures to be followed but before going any further, it is essential that you understand the following three points: Point 1: The weight of water displaced by a vessel does not simply equal cargo weight but consists of: • The weight of the cargo, if any on board. • The weight of the vessel itself, also called the light ship. • The weight of the liquids on board, also called deductible liquids, such as: o Ballast water required for stability. o Fresh water such as drinking water and cooling water. o Bunkers such as heavy fuel, diesel oil and lubricating oil. • The constant which is the total of all unknown weights on board.

Point 2: Since seawater (density 1025 kg/m³) is heavier than fresh water (density 1000 kg/m³) the volume of water displaced by an object floating in salt water is smaller than the volume of water displaced in fresh water. Or, when a ship is moved from fresh water into seawater, it will rise slightly out of the water because of the smaller volume of seawater displaced for the same weight.

Point 3: The data, represented in the vessel’s documents and required for draft survey calculation, are based upon a vessel: • Floating in water of a well defined density, usually 1025 kg/m³. • Being on even keel (= without trim) that is with equal drafts forward and aft. • Being upright (= without list) that is with equal drafts on port and starboard side. Unfortunately, these conditions are rarely encountered in practice and corrections will have to be applied. These will be explained in the following sections of the manual.

31

Section 5: Introduction 5.2 Introduction to the m/v "MINDIV" The m/v MINDIV is a hypothetical vessel with clearly specified dimensions as given below. This vessel will be used in the subsequent sections of the manual to illustrate the various techniques and calculations involved with a draft survey. General Particulars: Type of ship Dead weight Light ship Constant as per Chief Officer Length overall Length between perpendiculars Breadth moulded Summer freeboard Summer load draft

: Single deck bulk carrier : 26000 t : 5000 t : 200 t : 180.000 m : 170.000 m : 20.000 m : 3.000 m : 10.000 m

The general holds and tanks arrangement of the m/v Mindiv is presented in figure 1.

5.3 Abbreviations and conversion factors P S

: portside (left side from steering position) : starboard side (right side from steering position)

Fwd Aft Mid

: forward : after (abaft) : midships

Stem : the front side of a vessel (bow) Stern : the backside of a vessel 1 Foot = 1’ = 1 Ft = 12 inches 1 Inch = 1” MT = Metric Tonnes = Tonnes = To = Tn = t (the International Standard abbreviation) LT = Long Tons = Tons = Ts 1 Ft = 0.3048 m. 1 LT = 1.016047 MT.

32

Section 5: Introduction FIGURE 1

33

Section 6: Drafts SECTION 6 READING OR MEASURING THE DRAFT

6.1 Introduction In this section of the manual, we are going to consider the procedures for reading and measuring a vessel's draft - that is the depth of its keel in the water. These procedures rely upon marks which appear on every vessel and which are of known height above the keel.

Draft reading

:

direct reading of the draft from the draft marks marked on the hull of the vessel.

Draft measuring :

determining the draft by measuring the distance between a reference point on the hull of the vessel and the waterline.

During draft reading or measuring it is important to halt all operations on board which can change the position of the draft marks to the water such as: - Ballast operations (ballasting, deballasting or transfer of ballast water) - Bunker operations (bunkering or transfer of fuel, diesel etc.) - Gear operations (opening or closing of hatch covers; movement of booms, deck cranes etc.) - Loading or discharging operations of cargo or eventually other essential items. Note also the position of the anchors. Whenever possible, draft readings or measurements should be effected jointly with the Chief Officer or his representative. 6.2 Reading the Draft Seagoing vessels usually have six scales of draft marks painted or welded on the vessel's hull. These scales are positioned on port and starboard side of the vessel, forward, midships and aft. The value of each draft mark in these scales represents the distance from its position to the underside of the keel plate (extreme drafts - keel included). The scales can be calibrated either in meters (metric system) or in feet (imperial system). In some cases, both systems will be used. Taking a draft reading is simply a matter of noting the water level on the scale. Often this is not as easy as it sounds. The draft marks can be difficult to read, due to rust or poor painting, or the sea could be choppy or there could be a swell. Where the vessel is in a state of excessive trim, the stern or bow scales could even be clear of the water. To ensure the highest level of accuracy readings should be taken close to the water line, from a launch, if possible, to reduce the parallax error. Examples of metric and imperial draft scales are given in the following pages.

34

Section 6: Drafts METRIC SYSTEM FIGURE 2

FIGURE 3

35

Section 6: Drafts METRIC SYSTEM FIGURE 4

36

Section 6: Drafts IMPERIAL SYSTEM - ROMAN FIGURES FIGURE 5

37

Section 6: Drafts IMPERIAL SYSTEM - ROMAN FIGURES FIGURE 6

38

Section 6: Drafts IMPERIAL SYSTEM - ARABIC FIGURES FIGURE 7

39

Section 6: Drafts IMPERIAL SYSTEM - ARABIC FIGURES FIGURE 8

40

Section 6: Drafts 6.3 Measuring the Draft 6.3.1 Principle When the midships draft scale is not marked or cannot be clearly read, the draft must be measured indirectly. This is done by measuring the distance between the surface of the water and any point on the vessel's hull that is of known height above the keel. The measured distance is then subtracted from the height of the reference point above the keel. To illustrate this, let's consider a rectangular box 5.00 meters high (Figure 9). To determine its draft, the distance between the top of the box and the water is measured and this distance subtracted from the total height of the box. FIGURE 9

Total height of the box Distance between the top of the box and the water line Draft

5.00 m - 3.00 m 2.00 m

As you can see, this gives the same result as measuring the distance from the bottom of the box to the surface of the water. In the following sections of the manual, we will show that a vessel is merely a more complicated shape of box and that the same principles apply, provided that corrections are made to account for the profile of the vessel's hull. 6.3.2 Deck line and Load lines These compulsory lines (Figure 10) are marked in the midships position on the hull of every vessel on port and starboard side. Their primary function is to indicate the maximum permissible loading of the vessel in different zones and water types. However, because the lines are of known height above the keel, they can also be used to determine the vessel's draft. The deck line simply indicates the position of the deck.

41

Section 6: Drafts The summer load line or summer draft indicates the maximum permissible draft in seawater to which a vessel located in a summer zone can be loaded. This is often referred to as the Plimsoll line, after Mr. Plimsoll, who became concerned about the large number of vessels being lost due to overloading. The distance between the top of the deck line and the top of the summer load line is known as the summer freeboard. This distance will be specified in the vessel's International Load line Certificate which must be in the possession of the vessel's master. The summer freeboard should not be confused with the vessel's freeboard, which is simply the distance between the deck line and the water line. FIGURE 10

The other marks on the loading scale indicate the maximum draft to which the vessel can be loaded in different zones in fresh water (left side) and salt water (right side). The letters denote the zone and water type. For example, the fresh water line F indicates the level to which the vessel can be loaded in a summer zone in fresh water (and still be on the salt water line when it reaches the sea). The WNA or Winter North Atlantic zone is only applicable for vessels up to 100 m length. The locations of the different zones are presented in figure 11. And a practical example of a hydrostatic document with the positions of the summer load line and the deck line of the m/v Emerald is shown in figure 12.

42

Section 6: Drafts FIGURE 11

43

Section 6: Drafts FIGURE 12

44

Section 6: Drafts The load lines can only be certified by certain classification bodies. To ensure their accuracy, they must be checked at approximately twelve monthly intervals. The date of the last survey will be indicated on the International Load line Certificate. COUNTRY Britain France Germany Norway Italy United States Russia Japan

CLASSIFICATION BODY Lloyds Register of Shipping Bureau Veritas Germanischer Lloyds Den Norske Veritas Registro Italiano Navale American Bureau of Shipping Register of Shipping of the USSR Nippon Kaizi Ngokai

6.3.3 Measuring the draft on the m/v Mindiv The figure below shows the load line arrangement of the m/v Mindiv. FIGURE 13

45

ABBREVIATION LR BV GL NV RI ABS PC NK

Section 6: Drafts Because the heights of the marks above the keel are given in the vessel's general particulars, the midships draft is easily determined. This can be done in two ways. The first method is to measure the distance between the top of the summer load line and the surface of the water and to subtract this from the known height of the summer load line above the keel. FIGURE 14

Height of the summer load line above the keel Measured distance between the summer load line and the water Draft

: 10.00 m : - 4.00 m : 6.00 m

Alternatively, the draft could be found by measuring the distance between the top of the deck line and the surface of the water and subtracting this from the known height of the deck line above the keel. FIGURE 15

Height of the deck line above the keel Measured distance between the deck line and the water Draft

46

: 13.00 m : - 7.00 m : 6.00 m

Section 6: Drafts As you can see, both methods give the same result. In fact, any mark on a vessel's hull of known height above the keel can be used to determine the draft. For example, where draft marks are illegible or corroded or when the vessel is close to the quay and the marks cannot be read, the draft could be obtained by measuring the distance from a legible draft mark to the water line. A practical example of measuring the draft from the top of the deck line is presented below. FIGURE 16

47

Section 6: Drafts FIGURE 17

FIGURE 18

48

Section 6: Drafts 6.4 Calculation of the mean drafts fwd, aft and midships The objective is to calculate out of the six drafts, obtained by reading or measuring, one representative draft (quarter mean). This will have to be done in different steps. The first step will be the calculation of the mean drafts fwd, aft and mid. These mean drafts are simply the means of the port and starboard side drafts on fwd, aft and midships e.g.: Observed draft fwd P Observed draft fwd S Observed mean draft fwd

: 1.630 m : 1.630 m : 1.630 m

Observed draft aft P Observed draft aft S Observed mean draft aft

: 4.230 m : 4.190 m : 4.210 m

Observed midships P Observed midships S Observed mean draft mid

: 2.740 m : 3.010 m : 2.875 m

The next step will be the correction of these three mean drafts to the perpendiculars (see next section).

6.5 Exercise m/v Mindiv Observed draft fwd P Observed draft fwd S

: :

7.620 m 7.660 m

Observed draft aft P Observed draft aft S

: :

10.260 m 10.380 m

Observed midships P Observed midships S

: :

8.860 m 9.140 m

Calculate the mean drafts fwd, aft and mid.

49

Section 7: Perpendiculars SECTION 7 PERPENDICULAR CORRECTION

7.1 Introduction Perpendiculars are imaginary vertical lines, dividing the length of the vessel into two equal parts, in order to simplify various calculations such as trim, stability, etc. Ships documents are always based on draft readings at the perpendiculars. When a draft mark is not situated at its perpendicular then the observed draft reading needs to be corrected to the perpendicular. FIGURE 19

FP or fwd perpendicular

: An imaginary vertical line at right angle to the keel situated at the point where the summer load line intersects the vessel's stem.

AP or aft perpendicular

: An imaginary vertical line at right angle to the keel passing through the first frame (zero frame) and therefore located on or nearby the ship's rudderpost.

MP or midships perpendicular

: An imaginary vertical line at right angle to the keel situated midway between the FP and the AP

LBP or Length Between Perpendiculars : Distance between the FP and the AP. Observed draft

: Draft read on the vessel

Corrected draft

: Draft corrected to its perpendicular

50

Section 7: Perpendiculars Observed Trim Corrected Trim

: Difference between the observed mean drafts fwd and aft. : Difference between the corrected mean drafts fwd and aft.

Trim F Trim A

: Trim Fwd / by the head / by bow / by the stem / draft aft < draft fwd : Trim Aft / by the stern / draft aft > draft fwd

It is useful to know that the numbering of the frames usually starts from aft and that the AP is at the position of the first frame usually marked 0 (zero) on the plans, although on USA built vessels and some other ones frame numbering starts from fwd.

7.2 Position of the draft marks The following figure illustrates how draft marks can be situated on or away from their perpendiculars. FIGURE 20

The fwd draft mark scale is situated 2.0 m aft of the FP. The midships draft mark scale is located 0.5 m aft of the MP. The aft draft mark scale consists of two sections. The section from 8 m up to 12 m is located on the AP, the section below 8 m is located 7.0 m fwd of the AP. When correcting a draft reading to its perpendicular, the first step is to find the distance between the observed draft mark and the perpendicular. This distance is sometimes directly presented in the vessel's documents. If not, it may be estimated by aligning the position of the observed draft mark and its perpendicular to the quay and then measuring the distance between those markings. Also a ship's plan, on scale, might help to determine this distance. The distance between the midships drafts and the MP, which passes through the middle of the Plimsoll circle, can sometimes be measured directly on the hull. Be attentive when the fwd draft marks follow the profile of the vessel's hull (Figure 3 & 19). In this case the distance between the draft marks and the FP will vary depending on the draft of the vessel. The following pictures show some practical examples of draft mark positions.

51

Section 7: Perpendiculars FIGURE 21

FIGURE 22

52

Section 7: Perpendiculars FIGURE 23

FIGURE 24

53

Section 7: Perpendiculars FIGURE 25

7.3 Principle of perpendicular correction 7.3.1 Even keel condition Consider a vessel floating on even keel that is without trim or with equal drafts fwd and aft. FIGURE 26

O denotes observed draft and C corrected draft.

54

Section 7: Perpendiculars Both fwd and midships drafts are not observed at their perpendiculars but at a position aft of them. However, since the vessel is on even keel, these observed draft readings equal the required readings on their perpendiculars and no correction has to be applied (O=C). The aft draft is observed on the perpendicular (AP) and requires no correction. In other words, a perpendicular correction is not required when the vessel is on an even keel or when the draft mark is situated on the perpendicular. 7.3.2 Trim by the stern

FIGURE 27

Both fwd and midships observed draft readings do not equal anymore the required readings on their perpendiculars (O≠C) and corrections will have to be applied. It is also clear from this figure that readings on the perpendiculars would turn out lower than the observed draft readings (CO). The corrections will have to be added from the observed drafts. A reading on the aft perpendicular (AP) would turn out lower than the observed draft reading (C