Merchant Ship Stability

320 Pages·1985·8.09 MB·English

by  A.R. Lester (Auth.)

Marine Engineering Series
MARINE AUXILIARY MACHINERY—6th edition
David W Smith, CEng, MIMarE
POUNDER'S MARINE DIESEL ENGINES—6th edition
C T Wilbur, CEng, MIMarE and
D A Wight, BSc, CEng, MIMechE, FIMarE
MARINE ELECTRICAL PRACTICE—5th edition
G O Watson, FIEE, FAIEE, FIMarE
MARINE AND OFFSHORE CORROSION
Kenneth A Chandler, BSc, CEng, FIM, ARSM, FICorrT
MARINE AND OFFSHORE PUMPING AND PIPING SYSTEMS
J Crawford, CEng, FMarE
MARINE STEAM BOILERS-^th edition
J H Milton, CEng, FIMarE, and
Roy M Leach, CEng, MIMechE, FIMarE
MARINE STEAM ENGINES AND TURBINES-^th edition
S C McBirnie, CEng, FIMechE
MERCHANT SHIP STABILITY
Captain A R Lester, Extra Master, BA(Hons), MRINA, MNI
Merchant Ship
Stability
Captain A R Lester, Extra Master, BA(Hons), MRINA, MNI
Faculty of Maritime Studies, Plymouth Polytechnic
BUTTERWORTHS
London — Boston - Durban - Singapore — Sydney — Toronto - Wellington
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This book is sold subject to the Standard Conditions of Sale of Net
Books and may not be resold in the UK below the net price given by
the Publishers in their current price list.
First published 1985
(( ) Butterworth & Co (Publishers) Ltd, 1985
British Library Cataloguing in Publication Data
Lester, A.R.
Merchant ship stability.—(Marine engineering
series)
1. Merchant ships—Stability
I. Title II. Series
623.8º71 VM159
ISBN 0^08-01448-2
Library of Congress Cataloging in Publication Data
Lester, A. R. (Alan Robert)
Merchant ship stability.
Bibliography: p.
Includes index.
1. Stability of ships. 2. Merchant ships.
I. Title.
VM159.L47 1985 623.8º71 85-6621
ISBN 0-408-01448-2
Filmset by Mid-County Press, 2a Merivale Road, London SW15 2NW
Printed and bound in England by Garden City Press Ltd., Letchworth, Herts
Preface
This book is intended to serve the needs of the deck officer in a merchant
ship, as well as first year degree students and others at a similar level. The
work covered is sufficient to deal with the ship stability and stress syllabus
from cadet entry to master. Whenever possible the practical application
of theory to ship operations is presented in a form which is currently being
applied in practice.
It is assumed that readers will have a basic knowledge of physics
sufficient to deal with ideas of moments and elementary hydrostatics.
Wherever possible, alternatives to the methods of calculus have been
used; however, an elementary knowledge of integration and differen
tiation will enable the reader to gain a full understanding of basic
principles
Chapter 1 contains basic work on the form and measurement of ships.
The methods of Simpson's Rules have been used to present a means of
measuring ship form. While there are much more efficient methods
available, especially for computer application, Simpson's Rules are much
easier to present and to manipulate using calculators. Chapter 1 should
be used for reference as necessary rather than read straight through.
Chapters 2 to 10 are progressive as all information needed to deal with
current work is contained in previous chapters. As far as possible the work
presented within each chapter is also progressive, so that it is possible for
the elementary student to have a course of study based upon the early
parts of each chapter. The more advanced student can make use of more
information while having revision material at hand.
Chapter 11 'Stress' and Chapter 12 'Ship behaviour' both have links
with the previous work but are largely independent of the early chapters.
Specific examples of computer applications are not given. However,
where a particular process is generally applied as a computer program,
this is indicated in the text.
The author and publishers would like to thank Denholm Ship
Management Limited for permission to use the hydrostatic, stability and
stress data for one of their bulk carriers as a basis for the MVNonesuch data
which is used throughout the book.
A R Lester
"
Author's Note
Symbols are defined as they arise in the text, the following general
conventions have been used :
Upper case letters represent total values, i.e. W^for displacement, B for
buoyancy, KG for distance of centre of gravity of the ship above the keel.
Lower case letters represent elements of the total, i.e. w for a
component weight, Kg for the distance of a component weight from the
keel.
Where there is movement of centres of gravity, buoyancy, etc. then the
suffix o is used to indicate the original position and subsequent positions
by suffixes 1, 2, etc. In diagrams dashed lines are used to represent initial
conditions and solid lines final conditions.
Acknowledgements
I would like to thank my father John Lester for checking the arithmetic
and Jeffrey Cornwall and Richard Dakin for checking examples in the
later chapters. Any remaining errors are entirely my fault.
The author and publishers would also like to thank Mr P W Penney of
the Department of Naval Architecture and Shipbuilding, The University
of Newcastle upon Tyne for his helpful suggestions in connection with the
jacket design.
IShip form and
measurement
This chapter deals with the techniques of measurement which need to be
used in order to compute the various quantities which enable hydrostatic
and stability data for ships to be determined. It is not intended to be read
before the following chapters but is intended as reference material. As
such it should be consulted when particular topics are reached in the
subsequent work, where the techniques contained in this chapter are
required.
OBJECTIVES
1. To define the dimensions and form of ships.
2. To compute areas using the trapezoidal rule; Simpson's first, second
and 5, 8, — 1 Rules.
3. To apply the techniques in (2) to finding the first moment of areas and
volumes.
4. To apply the techniques in (2) to finding the second moments of areas.
5. To find the positions of the centroids of areas and volumes.
6. To find the second moments of areas about an axis through the
centroid.
7. To apply the values calculated to the determination of the hydrostatic
and stability data of ships and other floating platforms.
DEFINITIONS
See Figures 1.1 and 1.2.
Length between perpendiculars (L )
pp
The distance in metres on the summer load waterline from the fore side of
1
2 SHIP FORM AND MEASUREMENT
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SHIP FORM AND MEASUREMENT 3

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4 SHIP FORM AND MEASUREMENT
the stem to the after side of the rudder post; or to the centre of the rudder
stock if there is no rudder post. These forward and aft positions are termed
the 'Forward Perpendicular' (FP) and 'After Perpendicular' (AP)
respectively.
Length overall (L )
oa
The maximum length of the vessel from bow to stern.
Breadth (B)
The greatest breadth of the vessel.
Depth (D)
The depth of the vessel from the deck to the keel amidships.
Draft (d) (In some references, denoted T)
The distance from the waterline to the keel amidships.
Breadth, depth and draft may be either extreme, when the measurements
are taken to the outside of the shell plating, or moulded, when they are
taken to the inside of the shell plating. References to a dimension in this
book are to its extreme value, outside the shell plating, unless otherwise
stated.
Sheer
The rise in the deck line from amidships to the forward and after ends of
the vessel.
Camber
The rise of the deck from the side of the vessel to the centreline.
Rise of floor
The rise of the ship's bottom from the keel to the bilge.
RELATIONSHIPS BETWEEN DIMENSIONS
In order to ensure that conventional ship shapes have reasonable stability
and stress characteristics, constraints are imposed on the relationships
between the principle dimensions of ships. These relationships are
expressed as the ratio one dimension bears to another.