Basic Ship Theory

752 Pages·2001·10.201 MB·English

by  Rawson, K.J., Tupper, E.C.

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K.J. Rawson
MSc, DEng, FEng, RCNC, FRINA, hcShW
E.C. Tupper
,cSB ,gnEC RCNC, FRINA, hcShW
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r~UTTERWORTH
~E i N E M A N N
OXFORD AMSTERDAM BOSTON LONDON WEN YORK PARIS
NAS DIEGO NAS FRANCISCO SINGAPORE SYDNEY TOKYO
Butterworth-Heinemann
An imprint of Elsevier Science
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Wobum, MA, 01801-2041
First published by Longman Group Limited 1968
Second edition 1976 (in two volumes)
Third edition 1983
Fourth edition 1994
Fifth edition 2001
Reprinted 2002
Copyright © 2001, K.J. Rawson and E.C. Tupper. All fights reserved.
The right or K.J. Rawson and E.C. Tupper to be identified as the
authors of this work has been asserted in accordance with the
Copyright, Designs and Patents Act 1988
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(including photocopying or storing in any medium by eleclronic means
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8891 or under the terms of a licence issued by the Copyright Licensing
Agency Ltd, 90 Tottenham Court Road, London, England Wl T .PL4
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 Publication Data
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ISBN 0 7506 5398 1
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Foreword to the fifth edition
Over the last quarter of the last century there were many changes in the
maritime scene. Ships may now be much larger; their speeds are generally
higher; the crews have become drastically reduced; there are many different
types (including hovercraft, multi-hull designs and so on); much quicker and
more accurate assessments of stability, strength, manoeuvring, motions and
powering are possible using complex computer programs; on-board computer
systems help the operators; ferries carry many more vehicles and passengers;
and so the list goes on. However, the fundamental concepts of naval architec-
ture, which the authors set out when Basic Ship Theory was first published,
remain as valid as ever.
As with many other branches of engineering, quite rapid advances have been
made in ship design, production and operation. Many advances relate to the
effectiveness (in terms of money, manpower and time) with which older proced-
ures or methods can be accomplished. This is largely due to the greater
efficiency and lower cost of modern computers and proliferation of information
available. Other advances are related to our fundamental understanding of
naval architecture and the environment in which ships operate. These tend to
be associated with the more advanced aspects of the subject: more complex
programs for analysing structures, for example, which are not appropriate to a
basic text book.
The naval architect is affected not only by changes in technology but also by
changes in society itself. Fashions change as do the concerns of the public, often
stimulated by the press. Some tragic losses in the last few years of the twentieth
century brought increased public concern for the safety of ships and those
sailing in them, both passengers and crew. It must be recognized, of course,
that increased safety usually means more cost so that a conflict between money
and safety is to be expected. In spite of steps taken as a result of these
experiences, there are, sadly, still many losses of ships, some quite large and
some involving significant loss of life. It remains important, therefore, to strive
to improve still further the safety of ships and protection of the environment.
Steady, if somewhat slow, progress is being made by the national and interna-
tional bodies concerned. Public concern for the environment impacts upon ship
design and operation. Thus, tankers must be designed to reduce the risk of oil
spillage and more dangerous cargoes must receive special attention to protect
the public and nature. Respect for the environment including discharges into
the sea is an important aspect of defining risk through accident or irresponsible
usage.
A lot of information is now available on the Internet, including results of
much research. Taking the Royal Institution of Naval Architects as an example
XV
xvi Foreword to the fifth edition
of a learned society, its website makes available summaries of technical papers
and enables members to join in the discussions of its technical groups. Other
data is available in a compact form on CD-rom. Clearly anything that improves
the amount and/or quality of information available to the naval architect is to
be welcomed. However, it is considered that, for the present at any rate, there
remains a need for basic text books. The two are complementary. A basic
understanding of the subject is needed before information from the Internet
can be used intelligently. In this edition we have maintained the objective of
conveying principles and understanding to help student and practitioner in
their work.
The authors have again been in a slight dilemma in deciding just how far to
go in the subjects of each chapter. It is tempting to load the book with theories
which have become more and more advanced. What has been done is to
provide a glimpse into developments and advanced work with which students
and practitioners must become familiar. Towards the end of each chapter a
section giving an outline of how matters are developing has been included
which will help to lead students, with the aid of the Internet, to all relevant
references. Some web site addresses have also been given.
It must be appreciated that standards change continually, as do the titles of
organizations. Every attempt has been made to include the latest at the time of
writing but the reader should always check source documents to see whether
they still apply in detail at the time they are to be used. What the reader can rely
on is that the principles underlying such standards will still be relevant.
2001 K J R E C T
stnemegdelwonkcA
The authors have deliberately refrained from quoting a large number of refer-
ences. However, we wish to acknowledge the contributions of many practi-
tioners and research workers to our understanding of naval architecture, upon
whose work we have drawn. Many will be well known to any student of
engineering. Those early engineers in the field who set the fundamentals of
the subject, such as Bernoulli, Reynolds, the Froudes, Taylor, Timoshenko,
Southwell and Simpson, are mentioned in the text because their names are
synonymous with sections of naval architecture.
Others have developed our understanding, with more precise and compre-
hensive methods and theories as technology has advanced and the ability to
carry out complex computations improved. Some notable workers are not
quoted as their work has been too advanced for a book of this nature.
We are indebted to a number of organizations which have allowed us to draw
upon their publications, transactions, journals and conference proceedings.
This has enabled us to illustrate and quantify some of the phenomena dis-
cussed. These include the learned societies, such as the Royal Institution of
Naval Architects and the Society of Naval Architects and Marine Engineers;
research establishments, such as the Defence Evaluation and Research Agency,
the Taylor Model Basin, British Maritime Technology and MARIN; the
classification societies; and Government departments such as the Ministry of
Defence and the Department of the Environment, Transport and the Regions;
publications such as those of the International Maritime Organisation and the
International Towing Tank Conferences.
xvii
Introduction
In their young days the authors performed the calculations outlined in this
work manually aided only by slide rule and, luxuriously, calculators. The
arduous nature of such endeavours detracted from the creative aspects and
affected the enjoyment of designing ships. Today, while it would be possible,
such prolonged calculation is unthinkable because the chores have been
removed to the care of the computer, which has greatly enriched the design
process by giving time for reflection, trial and innovation, allowing the effects of
changes to be examined rapidly.
It would be equally nonsensical to plunge into computer manipulation with-
out knowledge of the basic theories, their strengths and limitations, which allow
judgement to be quantified and interactions to be acknowledged. A simple
change in dimensions of an embryo ship, for example, will affect flotation,
stability, protection, powering, strength, manoeuvring and many sub-systems
within, that affect a land architect to much less an extent. For this reason, the
authors have decided to leave computer system design to those qualified to
provide such important tools and to ensure that the student recognizes the
fundamental theory on which they are based so that he or she may understand
what consequences the designer's actions will have, as they feel their way
towards the best solution to an owner's economic aims or military demands.
Manipulation of the elements of a ship is greatly strengthened by such a 'feel'
and experience provided by personal involvement. Virtually every ship's char-
acteristic and system affects every other ship so that some form of holistic
approach is essential.
A crude representation of the process of creating a ship is outlined in the
figure.
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xviii
Introduction xix
This is, of course, only a beginning. Moreover, the arrows should really be
pointing in both directions; for example, the choice of machinery to serve speed
and endurance reflects back on the volume required and the architecture of the
ship which affects safety and structure. And so on. Quantification of the
changes is effected by the choice of suitable computer programs. Downstream
of this process lies design of systems to support each function but this, for the
moment, is enough to distinguish between knowledge and application.
The authors have had to limit their work to presentation of the fundamentals
of naval architecture and would expect readers to adopt whatever computer
systems are available to them with a sound knowledge of their basis and
frailties. The sequence of the chapters which follow has been chosen to build
knowledge in a logical progression. The first thirteen chapters address elements
of ship response to the environments likely to be met; Chapter 41 adds some of
the major systems needed within the ship and Chapter 51 provides some
discipline to the design process. The final chapter reflects upon some particular
ship types showing how the application of the same general principles can lead
to significantly different responses to an owner's needs. A few worked examples
are included to demonstrate that there is real purpose in understanding theoret-
ical naval architecture.
The opportunity, afforded by the publication of a fifth edition, has been
taken to extend the use of SI units throughout. The relationships between them
and the old Imperial units, however, have been retained in the Introduction to
assist those who have to deal with older ships whose particulars remain in the
old units.
Care has been taken to avoid duplicating, as far as is possible, work that
students will cover in other parts of the course; indeed, it is necessary to assume
that knowledge in all subjects advances with progress through the book. The
authors have tried to stimulate and hold the interest of students by careful
arrangement of subject matter. Chapter 1 and the opening paragraphs of each
succeeding chapter have been presented in somewhat lyrical terms in the hope
that they convey to students some of the enthusiasm which the authors them-
selves feel for this fascinating subject. Naval architects need never fear that they
will, during their careers, have to face the same problems, day after day. They
will experience as wide a variety of sciences as are touched upon by any
profession.
Before embarking on the book proper, it is necessary to comment on the
units employed.
UNITS
In May 1965, the UK Government, in common with other governments,
announced that Industry should move to the use of the metric system. At the
same time, a rationalized set of metric units has been adopted internationally,
following endorsement by the International Organization for Standardization
using the Syst6me International d'Unit6s (SI).
The adoption of SI units has been patchy in many countries while some have
yet to change from their traditional positions.
xx Introduction
In the following notes, the SI system of units is presented briefly; a fuller
treatment appears in British Standard 5555. This book is written using SI units.
The SI is a rationalized selection of units in the metric system. It is a coherent
system, i.e. the product or quotient of any two unit quantities in the system is
the unit of the resultant quantity. The basic units are as follows:
Quantity Name of unit Unit symbol
Length metre m
Mass kilogramme kg
Time second s
Electric current ampere A
Thermodynamic temperature kelvin K
Luminous intensity eandela cd
Amount of substance mole mol
Plane angle radian rad
Solid angle steradian sr
Special names have been adopted for some of the derived SI units and these
are listed below together with their unit symbols:
Physical quantity SI unit Unit symbol
Force newton N = kg m/s 2
Work, energy joule J = N m
Power watt W = J/s
Electric charge coulomb C = A s
Electric potential volt V = W/A
Electric capacitance farad F = A s/V
Electric resistance ohm fl = V/A
Frequency hertz Hz = s '-I
llluminance lux xI = Im/m 2
Self inductance henry H = V s/A
Luminous flux lumen lm = cd sr
Pressure, stress pascal Pa = N/m 2
megapascal MPa = N/ram 2
Electrical conductance siemens S = 1/fl
Magnetic flux weber Wb = V s
Magnetic flux density tesla T = Wb/m 2
The following two tables list other derived units and the equivalent values of
some UK units, respectively:
Physical quantity SI unit Unit symbol
Area square metre m 2
Volume cubic metre m 3
Density kilogramme per cubic metre kg/m 3
Velocity metre per second m/s
Angular velocity radian per second rad/.s
Acceleration metre per second squared m/s 2
Introduction drx
Angular acceleration radian per second squared rad/s 2
Pressure, stress newton per square metre N/m 2
Surface tension newton per metre N/m
Dynamic viscosity newton second per metre squared N s/m 2
Kinematic viscosity metre squared per second m2/s
Thermal conductivity watt per metre kelvin W/(mK)
Quantity Imperial unit Equivalent SI units
Length I yd 0.9144 m
I ft 0.3048 m
I in 0.0254 m
1 mile 1609.344 m
1 nautical mile 1853.18m
(UK)
1 nautical mile 1852m
(International)
Area 1 in 2 645.16 x 01 -6 m 2
1 ft 2 0.092903 m 2
I yd 2 0.836127 m 2
1 mile 2 2.58999 x l06 m 2
Volume I in 3 16.3871 x 10 -6 m 3
I ft 3 0.0283168 m 3
1 UK gal 0.004546092m 3 = 4.546092 litres
Velocity i ft/s 0.3048 m/s
I mile/hr 0.44704 m/s; 1.60934 km/hr
I knot (UK) 0.51477 m/s; 1.85318 km/hr
I knot (International) 0.51444 m/s; 1.852 km/hr
Standard acceleration, g 32.174 ft/s 2 9.80665 m/s 2
Mass 1 lb 0.45359237 kg
I ton 1016.05kg = 1.01605 tonnes
Mass density 1 lb/in 3 27.6799 x 301 kg/m 3
1 lb/ft 3 16.0185 kg/m 3
Force 1 pdl 0.138255 N
1 lbf 4.44822 N
Pressure 1 lbf/in 2 6894.76 N/m 2 0.0689476 bars
Stress I tonf/in 2 15.4443 x 601 N/m 2
15.443 MPa or N/ram 2
Energy 1 ft pdl 0.0421401 J
1 ft lbf 1.35582 J
I cal 4.1868 J
1 Btu 1055.06 J
Power I hp 745.700 W
Temperature 1 Rankine unit 5/9 Kelvin unit
1 Fahrenheit unit 5/9 Celsius unit
Note that, while multiples of the denominators are preferred, the engineering
industry has generally adopted N/mm: for stress instead of MN/m 2 which has,
of course, the same numerical value and are the same as MPa.
xxii Introduction
Prefixes to denote multiples and sub-multiples to be affixed to the names of
units are:
Factor by which the unit is multiplied Prefix Symbol
1 000000000 000 = 2101 tera T
1 000000 000= 901 giga G
i 000 000 = 601 mega M
I 000 = 501 kilo k
100 = 201 hecto h
10 = 10 t deca da
0.1 = 10 -I deci d
0.01 = 01 -2 centi c
0.001 = 10 -3 milli m
0.000001 = 10 -6 micro
0.000000 001 = 01 -9 nano n
0.000000000001 = 01 -12 pico p
0.000000 000000001 = 01 -l~ femto f
0.000 000 000 000000 001 = 10 --is atto a
We list, finally, some preferred metric values (values preferred for density of
fresh and salt water are based on a temperature of 15 °C (59°F)).
Item Aceepted Imperial Direct metric Preferred SI value
figure equivalent
Gravity, g 32.17 ft/s 2 9.80665 m/s 2 9.807 m/s 2
Mass density 64 lb/ft 3 ! .0252 tonne/m 3 1.025 tonne/m 3
salt water 35 ftJ/ton 0.9754 m3/tonne 0.975 m3/tonne
Mass density 62.2 lb/ft 3 0.9964 tonne/m 3 1.0 tonne/m 3
fresh water 36 ft3/ton 1.0033 m3/tonne 1.0m3/tonne
Young's modulus E (steel) 13,500 tonf/in 2 2.0855 × 701 N/cm 2 209 GN/m 2 or GPa
Atmospheric pressure 14.7 lbf/in 2 101,353 N/m 2 501 N/m 2 or Pa
10.1353 N/cm 2 or 1.0 bar
TPI (salt water) 6T-4Aw tonf/in 1.025 Aw(tonnef/m) 1.025 Awtonnef/m
A.(ft )2 m(wA )2
NPC 100.52 )me/N(wA
NPM A,,(m 2) 10,052 dw(N/m) 401 Aw(N/m)
AGML tonf ft
MCT "1 (salt water)
(Units of tonf and feet) 12L in
One metre trim moment,
tonnef m
(A in MN or - - , A in tonnef)
m
Force displacement A I tonf 1.01605 tonnef 1.016 tonnef
9964.02N 9964 N
Mass displacement I ton 1.01605 tonne 1.016 tonne
Weight density:
Salt water 0.01 MN/m 3
Fresh water 0.0098 MN/m 3
Specific volume:
Salt water 99.5m3/MN
Fresh water 102.0m3/MN