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Basic Ship Theory
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Basic Ship Theory
K.J. Rawson
MSc, DEng, FEng, RCNC, FRINA, WhSch
E.C. Tupper
BSc, CEng, RCNC, FRINA, WhSch
Fifth edition
Volume 2
Chapters 10 to 16
Ship Dynamics and Design
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
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Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 01801-2041
Adivision of Reed Educational and Professional Publishing Ltd
Amember of the Reed Elsevier plc group
First published by Longman Group Limited 1968
Second edition 1976 (in two volumes)
Third edition 1983
Fourth edition 1994
Fifth edition 2001
#
K.J. Rawson and E.C. Tupper 2001
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

1 Art or science?
2 Some tools
3 Flotation and trim
4 Stability
5 Hazards and protection
6 The ship girder
7 Structural design and analysis
8 Launching and docking
9 The ship environment and human factors
Bibliography
Answers to problems
Index
Volume 2
Foreword to the ®fth edition xi
Acknowledgements xiii
Introduction xiv
References and the Internet xvii
Symbols and nomenclature xviii
General xviii
Geometryof ship xix
Propeller geometryxix
Resistance and propulsion xix
Seakeeping xx
Manoeuvrabilityxxi
Strength xxi
Notes xxii
v
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10 Powering of ships: general principles 381
Fluid dynamics 382

Speed trials 419
Cavitation viewing trials 420
Service trials 421
Experiments at full scale 421
Summary 423
Problems 423
11 Powering of ships: application 427
Presentation of data 427
Resistance data 427
Propeller data 432
Power estimation 434
Resistance prediction 434
Appendage resistance 436
vi Contents
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1978 ITTC performance prediction method 438
Eect of small changes of dimensions 440
Variation of skin frictional resistance with time out of dock 442
Resistance in shallow water 443
Calculation of wind resistance 445
Propeller design 449
Choice of propeller dimensions 449
Propeller design diagram 453
Cavitation 460
In¯uence of form on resistance 460
Reducing wave-making resistance 462
Boundarylayer control 463
Compatibilityof machineryand propeller 463
Strength of propellers 463
Eect of speed on endurance 464

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Experiments and trials 531
Test facilities 531
Conduct of ship trials 532
Stabilizer trials 534
Problems 534
13 Manoeuvrability 539
General concepts 539
Directional stabilityor dynamic stabilityof course 540
Stabilityand control of surface ships 542
The action of a rudder in turning a ship 546
Limitations of theory547
Assessment of manoeuvrability 547
The turning circle 547
Turning ability550
The zig-zag manoeuvre 551
The spiral manoeuvre 552
The pull-out manoeuvre 553
Standards for manoeuvring and directional stability554
Rudder forces and torques 555
Rudder force 555
Centre of pressure position 558
Calculation of force and torque on non-rectangular rudder 560
Experiments and trials 564
Model experiments concerned with turning and manoeuvring 564
Model experiments concerned with directional stability565
Ship trials 567
Rudder types and systems 568
Types of rudder 568
Bow rudders and lateral thrust units 570

Life saving appliances 620
Creating a ®ghting ship 621
General 621
Weapons and ®ghting capabilities 621
Integration of ship, sensors and weapons 623
Accommodation 623
Measurement 626
Problems 630
15 Ship design 633
Objectives 634
Economics 635
Cost eectiveness 637
Boundaries 639
Economic, ethical and social boundaries 639
Geographical, organizational and industrial boundaries 640
Time and system boundaries 640
Creativity 641
Iteration in design 642
Design phases 644
Prime parameters 645
Parametric studies 649
Feasibilitystudies 652
Full design 654
Computer-aided design (CAD) 659
Design for the life intended 661
Design for use 661
Design for production 663
Design for availability663
Design for support 667
Design for modernization 667

Forewordto the ®fth edition
Over the last quarter of the last centurythere were manychanges in the
maritime scene. Ships maybe now much larger; their speeds are generally
higher; the crews have become drasticallyreduced; there are manydierent
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 ®rst published,
remain as valid as ever.
As with manyother branches of engineering, quite rapid advances have been
made in ship design, production and operation. Manyadvances relate to the
eectiveness (in terms of money, manpower and time) with which older proced-
ures or methods can be accomplished. This is largelydue to the greater
eciencyand lower cost of modern computers and the proliferation of infor-
mation available. Other advances are related to our fundamental understand-
ing 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 appro-
priate to a basic text book.
The naval architect is aected not onlybychanges in technologybut also by
changes in societyitself. Fashions change as do the concerns of the public, often
stimulated bythe press. Some tragic losses in the last few years of the twentieth
centurybrought increased public concern for the safetyof ships and those
sailing in them, both passengers and crew. It must be recognized, of course,
that increased safetyusuallymeans more cost so that a con¯ict between money
and safetyis 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 signi®cant loss of life. It remains important, therefore, to strive

organizations. Everyattempt has been made to include the latest at the time of
writing but the reader should always check source documents to see whether
theystill applyin detail at the time theyare to be used. What the reader can rely
on is that the principles underlying such standards will still be relevant.
2001 KJR ECT
xii Foreword to the fifth edition
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Acknowledgements
The authors have deliberatelyrefrained from quoting a large number of
references. However, we wish to acknowledge the contributions of manyprac-
titioners and research workers to our understanding of naval architecture, upon
whose work we have drawn. Manywill be well known to anystudent of
engineering. Those earlyengineers in the ®eld 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 technologyadvanced and the abilityto 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 quantifysome of the phenomena dis-
cussed. These include the learned societies, such as the Royal Institution of
Naval Architects and the Societyof 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
classi®cation societies; and Government departments such as the Ministryof
Defence and the Department of the Environment, Transport and the Regions;
publications such as those of the International Maritime Organisation and the

Self inductance henryH  Vs=A
Luminous ¯ux lumen lm  cd sr
Pressure, stress pascal Pa  N=m
2
megapascal MPa  N=mm
2
Electrical conductance siemens S  1=
Magnetic ¯ux weber Wb  Vs
Magnetic ¯ux densitytesla T  Wb=m
2
In the following two tables are listed 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
Densitykilogramme per cubic metre kg=m
3
Velocitymetre per second m=s
Angular velocityradian per second rad=s
xiv
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Acceleration metre per second squared m=s
2
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

2
0:836127 m
2
1 mile
2
2:58999 Â 10
6
m
2
Volume 1 in
3
16:3871 Â 10
À6
m
3
1ft
3
0:0283168 m
3
1 UK gal 0:004546092 m
3
 4:546092 litres
Velocity1 ft/s 0:3048 m=s
1 mile/hr 0:44704 m=s; 1:60934 km=hr
1 knot (UK) 0:51477 m=s; 1:85318 km=hr
1 knot
(International)
0:51444 m=s; 1:852 km=hr
Standard acceleration, g 32:174 ft=s
2

1 ft lbf 1:35582 J
1 cal 4:1868 J
1 Btu 1055:06 J
Power 1 hp 745.700 W
Temperature 1 Rankine unit 5=9 Kelvin unit
1 Fahrenheit unit 5=9 Celsius unit
Introduction xv
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Pre®xes to denote multiples and sub-multiples to be axed to the names of
units are:
Factor bywhich the unit is multiplied Prefix Symbol
1 000 000 000 000  10
12
tera T
1 000 000 000  10
9
giga G
1 000 000  10
6
mega M
1 000  10
3
kilo k
100  10
2
hecto h
10  10
1
deca da
0:1  10

figure
Direct metric
equivalent
Preferred SI value
Gravity, g 32:17 ft=s
2
9:80665 m=s
2
9:807 m=s
2
Mass density64 lb=ft
3
1:0252 tonne=m
3
1:025 tonne=m
3
salt water 35 ft
3
=ton 0:9754 m
3
=tonne 0:975 m
3
=tonne
Mass density62:2lb=ft
3
0:9964 tonne=m
3
1:0 tonne=m
3
fresh water 36 ft

9
>
>
>
>
=
>
>
>
>
;
8
>
>
>
>
<
>
>
>
>
:
A
w
420
tonf=in 1:025 A
w
tonnef=m1:025 A
w
tonnef=m

in
(Units of tonf and feet)
One metre trim moment
ÁGM
L
L
MN m
m

ÁGM
L
L
MN m
m

(Á in MN or
tonnef/m
m
, Á in tonnef)
Force displacement Á 1 tonf 1.01605 tonnef 1.016 tonnef
9964.02 N 9964 N
Mass displacement Æ 1 ton 1.01605 tonne 1.016 tonne
Weight density:
Salt water 0:01 MN=m
3
Fresh water 0:0098 MN=m
3
Speci®c volume:
Salt water 99:5m
3

h
w
, 
w
height of wave, crest to trough
H total head, Bernoulli
L length in general
L
w
,  wave-length
m mass
n rate of revolution
p pressure intensity
p
v
vapour pressure of water
p
I
ambient pressure at in®nity
P power in general
q stagnation pressure
Q rate of ¯ow
r, R radius in general
s length along path
t time in general
t

temperature in general
T period of time for a complete cycle
u reciprocal weight density, speci®c volume

! angular velocityor circular frequency
r volume in general
xviii
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GEOMETRY OF SHIP
A
M
midship section area
A
W
waterplane area
A
x
maximum transverse section area
B beam or moulded breadth
BM metacentre above centre of buoyancy
C
B
block coecient
C
M
midship section coecient
C
P
longitudinal prismatic coecient
C
VP
vertical prismatic coecient
C
WP

r displacement volume
Æ displacement mass
PROPELLER GEOMETRY
A
D
developed blade area
A
E
expanded area
A
O
disc area
A
P
projected blade area
b span of aerofoil or hydrofoil
c chord length
d boss or hub diameter
D diameter of propeller
f
M
camber
P propeller pitch in general
R propeller radius
t thickness of aerofoil
Z number of blades of propeller
 angle of attack
 pitch angle of screw propeller
RESISTANCE AND PROPULSION
a resistance augment fraction

P
E
eective power
P
I
indicated power
P
S
shaft power
P
T
thrust power
Q torque
R resistance in general
R
n
Reynolds' number
R
F
frictional resistance
R
R
residuaryresistance
R
T
total resistance
R
W
wave-making resistance
s

H
hull e.

O
propeller e. in open water

R
relative rotative eciency
 cavitation number
SEAKEEPING
c wave velocity
f frequency
f
E
frequencyof encounter
I
xx
, I
yy
, I
zz
real moments of inertia
I
xy
, I
xz
, I
yz
real products of inertia
k radius of gyration

T

natural period in smooth water for pitching
T

natural period in smooth water for rolling
Y

(!) response amplitude operatorÐpitch
Y

(!) response amplitude operatorÐroll
Y

(!) response amplitude operatorÐyaw
 leewayor drift angle

R
rudder angle
" phase angle between anytwo harmonic motions
 instantaneous wave elevation

A
wave amplitude
xx Symbols and nomenclature
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
w
wave height, crest to trough
 pitch angle

STRENGTH
a length of plate
b breadth of plate
C modulus of rigidity
" linear strain
E modulus of elasticity, Young's modulus
 direct stress

y
yield stress
g acceleration due to gravity
I planar second moment of area
J polar second moment of area
j stress concentration factor
k radius of gyration
K bulk modulus
l length of member
L length
M bending moment
M
p
plastic moment
M
AB
bending moment at A in member AB
m mass
P direct load, externallyapplied
P
E
Euler collapse load

1
2
L
3
, x
H
 x=
1
2
L
2
V
2
, L
H
 L=
1
2
L
3
V
2
.
(c) A lower case subscript is used to denote the denominator of a partial derivative, e.g.
Y
u
 @Y=@u.
(d ) For derivatives with respect to time the dot notation is used, e.g.

x  dx=dt.

ing characteristics is of considerable importance and that a fair expenditure of
eort is justi®ed in achieving it. For predicting full-scale resistance, the designer
can use full-scale data from ships built over a considerable period of years,
theoretical analysis or models.
Generally speaking, full-scale data is limited in usefulness because of the pro-
cess of evolution to which ships are subject. To mention two factors, the intro-
duction of welding led to a smoother hull, and ships have tended over the years
to become larger. Again, the new ship is often required to go faster so that data
from her predecessors cannot be used directly for assessing her maximum power.
Clearly, this method is not valid when a new ship form is introduced such as
the SWATH (Small Waterplane Twin Hull) ship or the trimaran.
381
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Theory has been used as an aid to more practical methods and continues to
develop. Computational ¯uid dynamics is a very powerful tool which is increas-
ingly used by researchers to study problems of ¯uid ¯ow, including those
involving cavitation but the main contribution of theory is still generally to
guide the model experimenter, providing a more rational and scienti®c back-
ground to his work, suggesting pro®table lines of investigation and indicating
the relative importance of various design parameters.
Where a methodical series of tests has been carried out on a form embracing
the new design, the details should be obtained from the literature. Even without
a methodical series, systematic plotting of previous data can provide a ®rst
estimate of power needs.
The main tool of the designer has been, and remains, the model with theory
acting as a guide and full-scale data providing the all-essential check on the
model prediction. The model is relatively cheap and results can be obtained
fairly rapidly for a variety of changes to enable the designer to achieve an
optimum design.
An example of the results obtainable by a judicious blend of theory and

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the ambient pressure, p
I
the velocity of sound in water, a
The quantitative values of some of these properties are discussed in Chapter 9.
Other factors involved are:
a typical length, usually taken as the wetted length L for resistance work,
and as the propeller diameter D for propeller design;
velocity, V
propeller revolutions, n
resistance, R
thrust, T
torque, Q
gravitational acceleration, g.
Dimensional analysis provides a guide to the form in which the above
quantities may be signi®cant. The pi theorem states that the physical relation-
ship between these quantities can be represented as one between a set of non-
dimensional products of the quantities concerned. It also asserts that the
functionally related quantities are independent and that the number of related
quantities will be three less (i.e. the number of fundamental unitsÐmass,
length, time) than the number of basic quantities.
Applying non-dimensional analysis to the ship powering problem, it can be
shown that:
R
V
2
L
2
 F
VL

5
 F
V
nD
;
VD

;
V
2
gD
;

gL
2
;
p
I
À p
v
V
2

Expressed in another way, it is physically reasonable to suggest that if data
can be expressed in terms of parameters that are independent of scale, i.e. non-
dimensional parameters, the same values of these data will probably be
obtained from experiments at dierent scales if the parameters are constant.
Where the governing parameters cannot be kept constant, data will change in
going from the model to full scale. The above are not the only non-dimensional
parameters that can be formed but they are those in general use. Each has been