ship stability for masters and mates [electronic resource]

Ship Stability for Masters and Mates Ship Stability for Masters and Mates Fifth edition Captain D. R. Derrett Revised by Dr C. B. Barrass OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd First published by Stanford Maritime Ltd 1964 Third edition (metric) 1972 Reprinted 1973, 1975, 1977, 1979, 1982 Fourth edition 1984 Reprinted 1985 First published by Reed Educational and Professional Publishing Ltd 1990 Reprinted 1990 (twice), 1991, 1993, 1997, 1998, 1999 Fifth edition 1999 Reprinted 2000 (twice), 2001 # D. R. Derrett 1984, 1990, 1999 and Reed Educational and Professional Publishing Ltd 1999 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 0LP. Applications for the copyright holder's written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publicaion Data A catalogue record for this book is available from the Library of Congress ISBN 0 7506 4101 0 Typesetting and artwork creation by David Gregson Associates, Beccles, Suffolk Printed and bound in Great Britain by Biddles, Guildford, Surrey A member of the Reed Elsevier plc group Contents Preface vii Introduction ix Ship types and general characteristics xi 1 Forces and moments 1 2 Centroids and the centre of gravity 9 3 Density and speci®c gravity 19 4 Laws of ¯otation 22 5 Effect of density on draft and displacement 33 6 Transverse statical stability 43 7 Effect of free surface of liquids on stability 50 8 TPC and displacement curves 55 9 Form coef®cients 61 10 Simpson's Rules for areas and centroids 68 11 Final KG 94 12 Calculating KB, BM and metacentric diagrams 99 13 List 114 14 Moments of statical stability 124 15 Trim 133 16 Stability and hydrostatic curves 162 17 Increase in draft due to list 179 18 Water pressure 184 19 Combined list and trim 188 20 Calculating the effect of free surface of liquids (FSE) 192 21 Bilging and permeability 204 22 Dynamical stability 218 23 Effect of beam and freeboard on stability 224 24 Angle of loll 227 25 True mean draft 233 26 The inclining experiment 238 27 Effect of trim on tank soundings 243 28 Drydocking and grounding 246 29 Second moments of areas 256 30 Liquid pressure and thrust. Centres of pressure 266 31 Ship squat 278 32 Heel due to turning 287 33 Unresisted rolling in still water 290 34 List due to bilging side compartments 296 35 The Deadweight Scale 302 36 Interaction 305 37 Effect of change of density on draft and trim 315 38 List with zero metacentric height 319 39 The Trim and Stability book 322 40 Bending of beams 325 41 Bending of ships 340 42 Strength curves for ships 346 43 Bending and shear stresses 356 44 Simpli®ed stability information 372 Appendix I Standard abbreviations and symbols 378 Appendix II Summary of stability formulae 380 Appendix III Conversion tables 387 Appendix IV Extracts from the M.S. (Load Lines) Rules, 1968 388 Appendix V Department of Transport Syllabuses (Revised April 1995) 395 Appendix VI Specimen examination papers 401 Appendix VII Revision one-liners 429 Appendix VIII How to pass exams in Maritime Studies 432 Appendix IX Draft Surveys 434 Answers to exercises 437 Index 443 vi Contents Preface This book was written primarily to meet the needs of the UK students when studying, either in their spare time at sea or ashore, for Department of Transport Certi®cates of Competency for Deck Of®cers and Engineering Of®cers. It will, however, also prove extremely useful to Maritime Studies degree students when studying the subject and will prove a ready and handy reference for those persons responsible for the stability of ships. I trust that this book, which is printed to include up-to-date syllabuses and specimen examination papers, will offer assistance to all of these persons. Acknowledgement is made to the Controller of Her Majesty's Stationery Of®ce for permission to reproduce Crown copyright material, being the Ministry of Transport Notice No. M375, Carriage of Stability Information, Forms M.V. `Exna' (1) and (2), Merchant Shipping Notice No. M1122, Simpli®ed Stability Information, Maximum Permissible Deadweight Diagram, and extracts from the Department of Transport Examination Syllabuses. Specimen examination papers given in Appendix VI are reproduced by kind permission of the Scottish Quali®cations Authority (SQA), based in Glasgow. Note: Throughout this book, when dealing with Transverse Stability, BM, GM and KM will be used. When dealing with Longitudinal Stability, i.e. Trim, then BM L ,GM L and KM L will be used to denote the longitudinal considerations. Hence no suf®x `T' for Transverse Stability, but suf®x `L' for the Longitudinal Stability text and diagrams. C. B. Barrass Introduction Captain D. R. Derrett wrote the standard text book, Ship Stability for Masters and Mates. In this 1999 edition, I have revised several areas of his book and introduced new areas/topics in keeping with developments over the last nine years within the shipping industry. This book has been produced for several reasons. The main aims are as follows: 1. To provide knowledg e at a basic level for those whose responsibilities include the loading and safe operation of ships. 2. To give maritime students and Marine Of®cers an awareness of problems when dealing with stability and strength and to suggest methods for solving these problems if they meet them in the day-to-day operation of ships. 3. To act as a good, quick reference source for those of®cers who obtained their Certi®cates of Competency a few months/years prior to joining their ship, port authority or drydock. 4. To help Masters, Mates and Engineering Of®cers prepare for their SQA/MSA exams. 5. To help students of naval architecture/ship technology in their studies on ONC, HNC, HND and initial years on undergraduate degree courses. 6. When thinking of maritime accidents that have occurred in the last few years as reported in the press and on television, it is perhaps wise to pause and remember the proverb `Prevention is better than cure'. If this book helps in preventing accidents in the future then the efforts of Captain Derrett and myself will have been worthwhile. Finally, I thought it would be useful to have a table of ship types (see next page) showing typical deadweights, lengths, breadths, C b values and designed service speeds. It gives an awareness of just how big these ships are, the largest moving structures made by man. It only remains for me to wish you, the student, every success with your Maritime studies and best wishes in your chosen career. Thank you. C. B. Barrass [...]... Stability for Masters and Mates Example 1 Whilst moving an object one man pulls on it with a force of 200 Newtons, and another pushes in the same direction with a force of 300 Newtons Find the resultant force propelling the object Component forces 300 N A 200 N >E > The resultant force is obviously 500 Newtons, the sum of the two forces, and acts in the direction of each of the component forces Resultant force... is acting away from the point Before completing the parallelogram, substitute either a force of 3 N acting away from the point for the force of 3 N towards the point as shown in Figure 1.4, or a force of 5 N towards the point for the Fig 1.4 3 4 Ship Stability for Masters and Mates Fig 1.5 force of 5 N away from the point as shown in Figure 1.5 In this way both of the forces act either towards or away... Dr C B Barrass Chapter 1 Forces and moments The solution of many of the problems concerned with ship stability involves an understanding of the resolution of forces and moments For this reason a brief examination of the basic principles will be advisable Forces A force can be de®ned as any push or pull exerted on a body The S.I unit of force is the Newton, one Newton being the force required to produce... below G, and that when discharged G will move vertically upwards to G1 12 Ship Stability for Masters and Mates In Figure 2.4(b), the mass is vertically above G and the ship' s centre of gravity will move directly downwards to G1 In Figure 2.4(c), the mass is directly to starboard of G and the ship' s centre of gravity will move directly to port from G to G1 In Figure 2.4(d), the mass is below and to... the ship takes a list and a quantity of grain shifts so that the surface of the grain remains parallel to the waterline Show the effect of this on the ship' s centre of gravity 16 Ship Stability for Masters and Mates f Fig 2.9 In Figure 2.9, G represents the original position of the ship' s centre of gravity when upright AB represents the level of the surface of the grain when the ship was upright and. .. substituted for a force of 10 Newtons (N) pulling to the right from the same point (a) Resolving two forces which act in the same straight line If both forces act in the same straight line and in the same direction the resultant is their sum, but if the forces act in opposite directions the resultant is the difference of the two forces and acts in the direction of the larger of the two forces 2 Ship Stability. .. considering a force the following points regarding the force must be known: (a) The magnitude of the force, (b) The direction in which the force is applied, and (c) The point at which the force is applied The resultant force When two or more forces are acting at a point, their combined effect can be represented by one force which will have the same effect as the component forces Such a force is referred... component forces and the resultant all act towards the point A Forces and moments Fig 1.2 Example 2 A ship steams due east for an hour at 9 knots through a current which sets 120 degrees (T) at 3 knots Find the course and distance made good The ship' s force would propel her from A to B in one hour and the current would propel her from A to C in one hour The resultant is AD, 0X97 1 Â 11X6 2 miles and this... resultant force acting on the body must be zero and the resultant moment about its centre of gravity must also be zero, if the centre of gravity be considered a ®xed point 6 Ship Stability for Masters and Mates `P'N Fig 1.8(a) Mass In the S.I system of units it is most important to distinguish between the mass of a body and its weight Mass is the fundamental measure of the quantity of matter in a body and. .. referred to as the `resultant force', and the process of ®nding it is called the `resolution of the component forces' The resolution of forces When resolving forces it will be appreciated that a force acting towards a point will have the same effect as an equal force acting away from the point, so long as both forces act in the same direction and in the same straight line Thus a force of 10 Newtons (N) pushing . Ship Stability for Masters and Mates Ship Stability for Masters and Mates Fifth edition Captain D. R. Derrett Revised by Dr C. B. Barrass OXFORD AUCKLAND BOSTON JOHANNESBURG. for Transverse Stability, but suf®x `L' for the Longitudinal Stability text and diagrams. C. B. Barrass Introduction Captain D. R. Derrett wrote the standard text book, Ship Stability for Masters. at 36  34 1 2 H to the 5 N force. Note. Notice that each of the component forces and the resultant all act towards the point A. 2 Ship Stability for Masters and Mates Fig. 1.1 <> >> EE E E E E )) ) ) Example