Proceedings of the 12th International Towing Tank Conference, ITTC69, Volume 2, Rome, Italy.

12TH INTERNATIONAL TOWING

TANK CONFERENCE

TECHNISCHE =VERNIER

Laboratorlum voor Schsepshydrortmolumioa Archive Malcolm* 2, 2128

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REPORT OF

MANOEUVRABILITY COMMITTEE

Rome, September 22-30, 1969

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P1969-8

1.,

PART 2

1--Pl 69

REPORT OF MANOEUVRABILITY COMMITrth Committee Members

Rear-Admiral J.E.P. Dieudonne - Chairman Mr M. Gertler

Prof K. Nomoto Mr N.H. Norrbin Mr A. Suarez Mr H. Thieme

Mr A.J. Vosper - Secretary

INTRODUCTION

The composition of the Committee has remained at the above seven

members, due to the refusal of the Executive Committee to agree on an eighth

member. This has handicapped the work of the Committee to some extent.

Since the inaugural meeting in Tokyo, the Committee has met on three

separate occasions, viz: in New York

1967,

Rome 1968 and Vienna

1969.

Although full attendance has been achieved on only one of these occasions, all members have been actively engaged in the tasks set by the 11th ITTC,

and these were as follows:

To keep under review the choice, definition and methods of measuring the quantities and qualities that must be considered to define the manoeuvrability properties of a ship.

To place especial emphasis on model test techniques and

associated prediction methods particularly in the new field of investigation of manoeuvring in restricted waters.

To continue the programme of comparison of the results obtained by different tanks with the same MARINER form with a view to

completing the final analysis before the 12th ITTC. Attempts

to be made to explain the reasons for discrepancies in the data produced by the various laboratories in terms of test technique

and scale effect.

To collate data on the correlation between model test and ship

trial results, In view of the need for such correlation data, all members of the ITTC are strongly urged to supply such data

to the Manoeuvrability Committee.

To collate information on the.problem of scale effect on model appendages as it affects manoeuvrability characteristics. The type of information required is outlined in Appendix 3 of

the Committeels Report to the Conference.

Not all of these tasks can be considered to be independent lines of enquiry, but for ease of reference they have been considered as such in this report and in the Appendices attached thereto, which are set out in the same

sequence.

ANTITIES AND UALITIES FOR D.LaNING MANOEUVRABILITY PROPERTIES

Considering these in turn, consideration of different manoeuvres

has taken up a considerable part of the Comnittee's time. It will be

recalled that at the 10th ITTC, the Conference accepted that the important /parameters

parameters defining the manoeuvring qualities and quantities of ships could be defined by the following standard manoeuvres:

Turning Circles designed to establish the turning performance,

and consisting of turns over a range of approach speeds and

rudder angles, with emphasis on maximum and 15 degrees angles. The data is derived from such tests in form of tactical

diameter and steady turning radius, advance and transfer. Zig-zag Manoeuvres designed to establish the response charac-teristics, and comprising a series of alternate rudder

executes at different approach speeds, the rudder movements being made at steady changes of heading. The recommended standard combination of 20 degrees rudder movement and 20

de-grees change of heading was accepted, and the data derived

from the test is in the form of overshoot angles and periods of oscillation.

Spiral Manoeuvres designed to establish a ship's directional stability and comprising a series of stepped decreases and increases in rudder movement over a range of 25 degrees Port and Starboard. At each step, steady conditions of turning

must be allowed to develope and the data is derived in the

form of turning rate against rudder angle. For an unstable

ship the important measures are height and width of the

Dieudonne loop.

Manoeuvres designed to establish the times for 5 degrees change of heading using 5 degrees of rudder angle, for a

range of approach speeds.

The Committee have no reason to revise its views on the value of the

turning circle data, but consideration has been given to the

zig-zag

and spiral manoeuvres.

So far as zig-zag manoeuvres are concerned, these have formerly been conducted on the basis of 20 degree rudder angle and 20 degree heading change. However, the advent of very large ships of high block coefficient

such as super-tankers, having marginally stable or slightly unstable

characteristics, has led to a re-examination of the need for smaller rudder angles and heading changes. In these vessels, yaw damping is small and

hence ship response is more sensitive to ship form and rudder configuration.

\There

are practical difficulties in undertaking zig-zag tests at small

rudder angles in unstable or marginally stable ships, particularly those

having large upperworks, due to the relatively large effects of wind and

tide on small headinff_chances._ nen zig-zag tests were first introduced

by Professor Kempf, they were tied to 10 degree rudder and heading angle,

but the 10th ITTC adopted the Committee's recommendation to standardise on

20 degrees. A number of shipowners and research associations have conducted zig-zag tests using different combinations of rudder angle and

heading change, and typical combinations of 15 degrees rudder and 5 degrees

heading change, and 10 degrees rudder, 2 degrees heading change have been proposed for consideration. The Committee consider that the usefulness of the zig-zag manoeuvre in determining the response characteristics would be enhanced by encouraging a study of combinations of rudder angle and heading

change other than the present standard of 20 degrees/20 degrees, and

consider that first attention should be given to combinations of 10 degrees/ 10 degrees and 20 degrees/10 degrees.

The spiral test procedure has also been the subject of examination in

the light of the so-called reversed spiral technique, first introduced by

Mr Bech.

It is claimed that this type of test can be run in a fraction of

the time required for a normal spiral, and it can be undertaken in

conjunc-tion with the ship's auto-pilot equipment.

The procedure involves actuating

the rudder so as to maintain a known turning rate, as opposed to the

proced-ure in the normal spiral test where the heading rate is measproced-ured for known,

steady rudder angles.

The Committee has been provided with test procedure

and some trials data by Mr Bach, together with some further Japanese trials

data for 190,000 ton tankers.

Some reservation is made by the Committee that the reversed spiral

techni ue is not a stead

state test

but its rota:.nists claim that it is

4a

a practical test for marginally stable and unstable ships which allows

wkinformation on directional stability to be obtained in about one-fifth of

the time that would otherwise be required.

The Committee has decided to

reserve its position on the acceptability of the reversed spiral as a

recommended standard manoeuvre, but meanwhile intends to endorse the use of

both methods, with the particular aim of obtaining data to enable a better

judgment to be made.

A further alternative test procedure to the standard spiral manoeuvre'

is the use of the pull-out and weave manoeuvres.

It has been found at AEW

Haslar that, even in a large Manoeuvring Tank, model spiral manoeuvres have

to be undertaken piecemeal.

For this reason, Mr Burcher has developed the

use of simplified procedures, consisting of pull-outs and weaves which, from

the limited experience with unstable forms so far available, show promise of

arriving at the height and width of a Dieudonne spiral loop in a much shorter

experiment time.

The pull-out manoeuvre consists simply of returning the

rudder to amidship from a steady turning state with 30 degrees or 35 degrees

of rudder, and measuring rate of change of heading with time.

_{In control}

terms it represents th-e-fE,-Wehse of a ship to a step input, in this

case the

removal of the rudder force.

.Separation of the plotted

trdair-cTliiTiarg--rate-With time, for Port and Starboard turns, gives the height of the unstable

loop in a Dieudonne spira

The weave manoeuvre is complementary to the pull-out in that its object

is to establish the smallest rudder angle which results in a reversal of the

rate of heading of the ship.

Appendix 1, contributed by Messrs Nomoto and Norrbin contains

a

compre-hensive review of the choice, definition amd methods of measuring the

manoeuvrability of ships, not all of which are necessarily endorsed.

MANOEUVRING IN RESTRICTED WATERS

The Committee's first concern has been to review the published work in

this field, and to establish what facilities exist for restricted water

work,

and what model test techniques are currently in use.

Because of the paucity

of data on the latter two aspects, a questionnaire has been formulated

_and

circulated amongst ITTC members, many of whom have agreed to

_{supply the}

Committee with information.

_{Replies to the questionnaire are now beginning}

to come in, and in time should enable the Committee to complete

a useful

review of facilities and to consider recommended test techniques.

The study of this subject has been considerably assisted by

_{the supply}

by Professor Motora of a collated report on the considerable

_{amount of work}

undertaken in Japan.

_{One of the most interesting aspects of this work is}

the effect of depth on directional stability.

_{Thus the behaviour of a ship}

is shown to change from stable condition in

very shallow water through an

unstable regime at medium depths and then back to

_{a stable condition in deep}

water.

_{Comparison of constrained model data shows considerable}

_{increase in}

body side forces and moments at angles of yaw as the water depth decreases.

Captive model tests are clearly preferable in furthering studies into

the

effect of restricted channels on manoeuvring qualities.

Appendix 2, contributed by Mr Norrbin in collaboration with Professor

Motora, contains a short bibliography, an outline of the current studies on

restricted water work in Japan, a review of test techniques and prediction methods and a summary of the few replies to the questionnaire.

MARINER OD-OPERATIVE TEST PROGRAMME

Analysis of free model data has continued. As an addition to the original programme, the Committee has recently received repeat model test data from the Rome Tank, together with the results of a very comprehensive

Japanese series in which a number of models of different scale have been

re-tested, some of which have been interchanged amongst various tanks. Constrained model data is still in relatively short supply due to the small number of rotating arm and PMM facilities available throughout the world. A new PMM has been commissioned at NSRDC Washington which has

enabled the collection of additional model data. Other PMM's capable of large amplitude oscillation are programmed to be commissioned in the next

year or two at the Danish. Hasler and Paris Tanksl_and it is hoped that

information from these facilities may be made available to the Committee in due course.

Appendix 3, which summarises the analyses of the free and constrained

model data is in two parts, contributed by Messrs Suarez and Gertler

respectively. The 11th ITTC expressed the hope that the Committee would find it possible to complete the final analysis of these data in time to present it in this report. However, while some progress has been made, the large amount.of data to be studied, some of which has only recently come to

hand, has led the Committee to two conclusions:

Free model data. Analysis of the discrepanciesshould concen-trate on the establishment of agreed standard test techniques. Constrained model data. The next step should be to invite the participating Establishments to use the model data to

predict full-scaleperformance for comparison with the

"Compass Island" trials data.

Copies of Parts 1 and 2 of this Appendix will be distributed separately by Messrs Suarez and Gertler, respectively.

CORRELATION DATA FROM MODEL TESTS AND SHIP TRIALS

Despite the urgent appeal for information in this field, limited data

is available, made up of a small number of relatively fine forms from Haslar, some Japanese data on cargo liners and tankers, and some French data on car ferries and a four-screw liner.

In this study, the Committee considered it more important to start by

comparison of steady state dateq, and correlation of circle manoeuvres has

been made by comparison of r'- data. For one of the Haslar forms,

rotat-ing arm data has been included in the correlation study as an illustration

of the scale effect on rudder forces. Unsteady state data from zig-zag

manoeuvres has been compared on basis of EY and T' indices, overawing angle

and turning lag.

It is clear that there is no single reason for the lack of correlation

between model and ship, but the Committee are agreed that the most likely

\cause

of the discrepancy is the differcm-e in intensity of the slipstream,

which is a function of ship fullness ar lfter body form needing further

research into effect of propeller slipstream on rudder action.

Three tentative conclusions from this exercise are:

In most cases, turning performance at large rudder angles is

practically free of scale for single-screw Japanese forms in

the intermediate speed range.

Stability in response to moderate rudder action is considerably

affected by scale, the ship being less stable amd more sluggish

in response to rudder action than its model.

The irregular flow pattern at full-bodied sterns considerably

affects model-ship correlation.

Appendix 4, prepared by Mr Vosper in collaboration with Professor

Nomoto, presents the results of this correlation study.

STUDY OF SCALE EFFECT

It will be recalled that the Committee's Report to the 11th ITTC

contained a comprehensive Appendix (p.516 et sec) contributed by Mr Thieme,

which dealt with all aspects of scale effects on rudders and other appendages, methods for correcting the same and suggestions for future research in this

important field. A very useful bibliography was also included. The

Conference endorsed the recommendation that the collation of information .

should continue and Mr Thieme has accordingly contributed Appendix 5 of this

report, in which he has developed the previous survey, taking note of a number of recent reports on ship-model correlation, which have provided

additional evidence of the actual effect of ship-model scaling. Progress

in theoretical analysis and experimental work directly relating to scale effect has not been so marked, so that the understanding of the hydrodynamics

of the problem has not greatly advanced since the last Conference. Separate

from Mr Thieme's work on scale effect, he has made available to the

Committee a bibliography of published contributions on Manoeuvrability in the

interval since the Tokyo Conference. Although it is not possible to

reproduce this useful reference document in the report, members may like to be made aware of its existence.

12TH ITTC MANOEUVRABILITY COMMITTEE REPORT'

APPENDIX I

A REVIEW OF METHODS OF DEFINING AND MEASURING THE MANOEUVRABILITY OF SHIPS

prepared by

K. Nomoto(Osaka Univ.) and N.H. Norrbin(SSPA)

Introduction

Since being established at the 9th ITTC the Manoeuvrability Com-mittee has kept under review the choice, definition and methods of measuring quantities and qualities necessary to define the

manoeuv-rability of ships. During these years a number of different ideas

and methods have been brought out. The purpose of the present

appendix is to make a short review of, and to present some discussion upon these methods, as applied to manoeuvring tests previously suggested.

1. Turning Trial

The terms "tactical diameter", "advance" and "transfer" has been well established for many years, and so there may be rather little need to discuss in details these measures of manoeuvrability /1/ . It may be mentioned here that Gertler and Gover suggested a certain figure of tactical diameter in ship length as a practical criterion for good handling performance of merchant ships /2/.

The "steady turning radius" is perhaps the most basic figure obtained from turning trials and we will come back again to it in the next paragraph.

There are a number of measuring means as employed in turning trials;

to track visually a target-buoy and draw the ship's path by triangulation;

to detect the yaw rate 9D and ship Teed V to get r' = L/R,

where L denotes ship length and R the turning radius ---- a ship's compass and log are conventional instruments, while use of a

rate-gyro and speed-meter of high performance yields better accuracy /3/;

to fix the ship's position with radio locating means/k/.

-1-,2. Spiral Test and r' - i Characteristics 2.1 Dieudonne Spiral Test

Dieudonne, the chairman of this Committee proposed in 1949 a new procedure of assesing the stability on course of a ship, named "spiral

test" /5/,/1/. This is essentially a series of measuring the steady

turning rates against rudder angles which are changed progressively.

The results give a

a

diagram shown in Fig.l. For course-stable

ships it makes a single curve and the smaller is the slope of the curve

near the origin, , the better the stability. For unstable ships

a hysteresis loop appears around the origin, as shown in the figure, and the larger is the width and height of the loop, the less stable

is a ship.

Gertler and Gover have given some standard figures of the loop height and width for a good handling quality for an average merchant

ships/2/ , while recent experience with very large oil-tankers is

showing that the permissible width may be further large in those giant ships.

2.2 r' - elliagram as a Measure of Steady-State Characteristics

Nondimensional form of the Dieudonn; diagram makes r'

-diagram, where

r' =

54*)

This gives a complete representation of

steady-state characteristics of a ship.

Apart from Dieudonne's procedure, it can be provided from

defining hydrodynamic moments acting upon the rudder and hull with a captive model experiment, for instance, rotating arm experiment or

alternatively with hydrodynamic calculations if provided that the

assumption for the calculation is valid enough.

The correlation of K-T analysis /6/ (also cf. paragraph 3.2) to

r' characteristics should here be related to. The index K

is theoretically defined as a ratio of steady turning rate to rudder

angle, so that its nondimensional equivalent K'. K/4/f..) becomes rt/1

In actual r' - j', however, it does not make a straight line as

expected from the linear analysis, but a curve shown in Fig.2. The

definition of K' may then be modified as K°O

where dr° and dS el

denote incremental r° and respectively, around a certain r' and

Jr

corresponding to this r'. K° thus re-defined is a function of r°

-2-and represented by the slope of r' icurve.

In actual application of K-T analysis, however, it is convenient

and reasonable approximation to take an average K' over the amplitude

of the motion in question and to regard K' as remaining

constant

at

this value. This "E' on the average", denoted as 7,, is represented

by the slope of the straight line connecting two points on r'

-curve, which correspond to r' amplitude, as indicated in Fig.2.

2.3 Reversed Spiral Test

Bech devised in 1966 a new procedure of obtaining

characteristics of an actual ship or a free-sailing model, called

"reversed spiral test" /7/. The theoretical verification are given

in this reference. fhis new procedure is to actuate the rudder so

as to keep a certain turning rate 90 and then take the time mean

values of SO and rudder angle,

I

. It requires a rate-gyroscope to

detect an instantaneous value of turning rate 90 The control of

rudder may be carried out manually by watching 90 desplay, but

an automatic control device specially prepared is considered more

preferable. Actual experience obtained up to now, whether with or

without automatic control , look promising. Figs. 3 and 4 illustrate

a few examples of test results.

The advantages claimed for this new procedure over the usual one may be summarized below:

full r' -

er

characteristics even including the unstable

equili-brium positions can be defined;

the width of the unstable loop can thus be defined accurately, which is sometimes rather ambiguous in the common procedure; the time required for the test can be considerably reduced

because this procedure brings a ship actively into a given turning rate, while the usual one pas:lively waits the settling of turning

rate.

3.Zig-Zag Test and Its Analysis

3.1

Direct Characteristic Numbers

The overawing angle has been used for years as a measure of

defined to be an extreme course deviation measured from the instant

when the rudder starts to move to the opposite side. It has been

believed that the smaller be this angle, the better the steering

quality. It should be noted, however, that a strong steady turning

rate with a quick response to the reversed rudder may give the same

overawing angle as a weak steady

turning

rate with a sluggish response.

The former implies a good manoeuvrability and the latter the opposite. The overswing angle can thus not always be a suitable measure of

manoeuvrability.

Kempf also proposed the use of nondimensional "period" of zig-zag tests as a measure of response promptness; there is no unique

correlation, however (see ref. /8/ and Fig' 5).

As an alternative measure that is obtainable directly from

zig-zag tests, the "course change lag" has been proposed by the first

author at 10th ITTC. This is defined as a time TL elapsed from

the instant when the rudder passed amidship to the instant when the

ship reaches at the extreme course deviation (cf. Fig.6). This means

a delay time of the occurence of the zero turning rate after the

V

zero rudder angle. T ( E ), the nondimensional equivalent of

TL' may be used as a relative measure of quick response to rudder

action, where V denotes ship speed and L ship length.

3.2 K-T Analysis of Zig-Zag Test

Mathematical analysis on ship motion indicates that the turning

angular rate

e

can be related to the rudder angle by an approximate

differential equation of the following form /6/:

+ ;4;

K/.

(1)

CIC

The "time constant" T represents the ratio of ship's inertia to

yaw-damping constant and the "gain" K the ratio of rudder turning moment constant to yaw-damping constant.

The K and T can be determined from the hydrodynamic derivatives,

which are obtained from captive model experiments and/or hydrodynamic

calculations, assuming that the ship motion is within the range over

which the linear analysis is valid. In actual manoeuvres, however,

ship motion does deviate more or less from that range, and the

coeffi-cients K and T may thus have values different from the ones in that

linear range. The concept of "linear on the average" is then called

the motion in ouestion and to regard K and T as remaining constant at

these values. _{The notations K and Y may be used for these average}

K and T. _{According to many actual results, this approximation works}

fairly well to interprete the motion of a ship in zig-zag tests, though

it is necessary to use different R and Y for tests with defferent

rudder angles of one same ship /6/4 the larger is the rudder angle, the larger the amplitude of the motion, and thus the smaller the values of the "average" K and T (cf. Fig.8).

In conclusion it may be said that ship motion in zig-zag tests can be expressed with Eq.(1) with K and T re-defined under the concept

of linear on the average. _{Based upon this conclusion, the K-T analysis}

of zig-zag tests then invloves the application of Eq(1) to the course

angle ?(' and rudder angle

1

, both recorded as a function of time t,

to find a best fit of

T

and T values. The actual procedure of this

analysis is given in reference /6/. Refering to the results of this

analysis for a variety of actual ships, it is proved to provide a

reasonable description of the manoeuvrability of ships in moderate manoeuvres/6/.

The correlation of the index T to the "course change lag"

TL,

as defined in the last paragraph (cf. Fig.6) is fairly consistent,

as expected from theoretical interpretation of TL. Fig.7 indicates

this correlation for a number of ships and free-sailing models.

This figure may yield a quick means of defining Y directly from

a zig-zag test; to read up TL from the record and reduce it into T°

and obtain

Y'

from the diagram.

3.3

Choice of Rudder Angles and Course Deviations to be used in

Zig-Zag Tests.

Kempf originally proposed 10' both for rudder angle and for the

course deviation at which rudder is to be reversed (the 100/ 10'zig-zag

test). Later 20' and/or 15* has become rather popular, and in

1963

this Committee proposed the 20./ 20' zig-zag test as a standard. _On

the other hand 5' is being used in some cases. This choice has

been discussed for these years. Points to be considered are

(1) that a zig-zag test should be a good representative of usual

manoeuvres of ships, that is keeping and moderate course-changing _it does not seem reasonable to use any zig-zag test to represent a hard-over steering and the turning trial would be better fit for that ;

,(2) that differences in steering qualities of ships of various designs

should be clearly discriminated by a zig-zag test;

(3)

that possible interferences of wind and sea upon a zig-zattest

should be minimized in order to get a consistent result.

From the point (1), the original choice of Kempf,

le,

is perhaps

the most reasonable, since rudder angles used in course-keeping in

usual conditions are largely within

5°

and in course-changing at sea

a rudder angle of 15° is the most popular except for emergency.

The use of small course deviation may yield, however, a good information about course-keeping quality of such ships having poor

stability, large oil-tankers for example. Motora and Thieme have

proposed 10 or 2° course deviation with 10° rudder angle for this

purpose. In contribution to the 10th ITTC, the second author also

suggested this type of manoeuvres to be run in order to identify the

more com lete transfer function at higher frequencies

/9/.

These

proposals are certainly worth considering, including the examination on the consistency of the new procedure with the mass of data already

obtained using 10, 15 and 20° course deviations.

From the point (2) the smaller angle of rudder and course

devia-tion are the better. This is because differences in steering

quali-ties among various designs in moderate steering largely come from

differences in yaw-damping, in other words, hydrodynamic moment

acting upon a turning ship. Stability on course and quick response

to rudder are governed by the ratio of the inertia of a ship to

the yaw-damping coefficient, i.e. "effective

yaw-damping"

divided by

yaw rate; the smaller is the ratio, the more stable is the ship and

the quicker in response. On the other hand,the inertia is not

very different among various designs, of course taking a nondimensional

expression. The yaw-damping coefficient changes its value with

yaw-rate (turning angular velocity), as the yaw-damping changes non-linearly

with yaw-rate. The coefficient in small motion is generally small,

for some ships it can be zero or even of opposite sign. This means

that in small motions the ratio of inertia to yaw-damping coefficient,

which governs stability and quick response, can be negative, very large

in negative, very large in positive(these two cases correspond to near

In harder motion, 20/207zig-zag for

instance,

the resistance to yaw is usually fairly large for most ships, so that stability and quick response are much less different among different ships in harder

motions than among those ships in small motions. This reasoning

can be verified by K-T analysis of zig-zag tests with different rudder angles for a number of ships, as illustrated by Fig.8.

The zig-zag test using small angles of rudder and course devia-tion thus have the advantage of making it possible to discriminate

clearly the steering qualities of different designs in small motion.

From the point (3) as raised before, however, too small rudder angles

should be avoided. According to experiences id/lo'zig-zag tests

can provide consistent results up to Force 4 in Beaufort scale for

large ships and Force 3 for smaller vessels. The

5/5

test seems

generally not to be much different in this point, but for ships with poor stability on course it is sometimes difficult to get sufficiently

accurate data. of

5/5'

test.

4. The Initial Change of Heading

4.1 The P Number as a Measure of Manoeuvrability

The second author proposed in 1965 the "course change quality

number" P as a measure of manoeuvrability. _{This is defined to be}

P = K° ( 1 - T' T'e- T° _),

where here the positive K' corresponds to a stable ship. _{P implies}

the ideal course change angle per rudder angle, realized one ship length travel after rudder execute, based upon Eq.(1),/10/.

He plotted the indices 17, and Tr, obtained from zig-zag tests

of many actual ships in a form of Fig.9 and reached a tentative conclusion that P> 0.3 may asr3ure a reasonable standard of course

change quality. Later the first author in a note to the Committee

added that for large oil-tankers P)0.2 would be sufficient according to data of those ships.

_1

Using the Taylor expansion of e

r°

the course change number P

can approximately be written in the form of

/ a

/

/

P =

(7,,)

(2)

This expression is valid also for marginally unstable ships. _This

be used conveniently to represent P.

Eq. (2) clearly tells us why P derived from zig-zag tests with

different rudder angles show much the same figure; the values of

R.

and T' sometimes change considerably, depending upon the amplitude

of the motion, but with much the same rate for both changes. The

physical interpretation of this fact is g,iven in reference/6/. In

a word, the course change quality here defined for marginally stable or uns9ob1e ships is largely governed by rudder effectiveness and

inertia of the ship with no regard to yaw-damping. Thus, for those

ships the P number has no direct bearing on the stability on course, and an additional parameter must be considered.

Now it may be concluded that:

P number is agpod measure of manoeuvrability for those ships with satisfactory course-stability;

for ships with poor stability the P may still provide an

inclusive measure of manoeuvrability if used together

with

another

index that represents stability on course.

As such a measure representing the stability on course to be used

together with P, the index T', the course change lag TL the slope

or the width of the loop in r° -

i

curve are feasible.

Ample

.

combination may be P / and

Y.,

both derived from 10/1e

2

7-,

zig-zag test. This can provide an inclusive measure of manoeuvrability

in moderate manoeuvres for stable and marginally stable ships.

4.2 Direct Experimental Results

A direct measure of the initial change of course may be obtained

from special tests with ships or free-sailing models. Here should

be mentioned the NSRDC procedure of plotting the time of change

heading

5°

on basis of the gradient

NON;

/),

which is obtained

from captive model tests. This "angular acceleration parameter"

is seen to be closely connected to the approximate P number discussed

in the last paragraph.

5.

Pull-Out and Weave Manoeuvres as a Quick Means of Assessing

Course-Stability

Recently Burcher devised a new test procedure of defining the

stability on course of a ship or free-sailing model, named "pull-out"

The "111)-out" involves a pair of manoeuvres in which the rudder is

returned to

amidahipu after ste,idy turninc has been attained, one o

Starboard

and the ether a port turn.

If a ship ia stable on COUVJQ, it approaches to

the same terminal

yaw-rate (;.;enerally small) in both cc.sea.

If

ship is

unstable, the

terminal yaw-rate

from the starboard turn is different from the

one from port, the terminal motion from

starboard

turn beinL; moderate starboard

turn and vice verua. The difference between the two

terminal

yz:iw-rates

corres-ponds exactly to the

heitihtofDieudonne spiral loop.

This stability

discrim-inative test ,:'13 retorted to be quite simple to conduct yet ver _effective.

In order to assess thi lej;ree of

stability for stable ships, the lcarithms

of rate of headin;;; chrwe in pull-out etare

are plotted a-inst time.

_{The slope}

of the plotted

curve

reprevente the

_{exponent of}

the exponential decay of the

y3'-rte. The more ne,-ttive the exponent, the better the

stAAlity on course.

Incidentally

-this

exponent

is equivalent to the

_{inverse of the time constant} T defined in ,sarm7rarh 1.2.

The "weave" manoeuvre is a

form of z.-z- j

stearin:,

:Jith small rudder

ami65.

lf the amplitude of the rudder motion exceeds the

width of the stiral

Pmp, ;. ship resronds to rudder in :1 recaar way. _{If the rudder amplitude is}

within the loop jd

tb,a ,:hi u mees a slow turn in response to the

_{first rudder}

am:le 1.1 not re71(41.1 to sul-:seluent reversal

of helm.

_{The loop width}

_can

th;I:1 be defined

_-4ith

the .v..yav..1 manoeuvre _{with a few ,,ifferent :710der amplitudes.}

It rerorted that the low- width

obtained in this n.iiy ;reed well

_{vith the}

one fro' Dieulennii spiral teat. _{(see fiures 1C and 11).}

rtEFERENCES

10

1.

ITTC :Janoeuvrability

Committee.

10th ITTC, Manoeuvrability Committee

Report, 1963

Gertler, M. and Gover, S.C. Handling Criteria for Surface Ships.

DTO Report,

1461, 1960

3. Morse, R.V. and Price, D. Manoeuvring Characteristics of the Mariner

Type Ship (Compass Island) in Calm Seas. Sperry Gyroscope Co.Pub No GJ-2233-1019,

1961

4.

Lindgren, H. and Norrbin, N.H. Model Tests and Ship Correlation for a

Cargo Liner. RINA 1961

5.

Dieudonner, J. Note sur la Stabilite du Regime de Route

des Navires.

Association Technique Maritime et Aeronautique, Session 1949 1949

6. Nomoto, K. 60th Anniversary Pub of Soo Naval Arch Japan, Vol 11, Chapter 2 1966

7.

Wagner-Smitt, L.

Bech's Re,inr9e,1

Teat.

flya Rp 10

1967

8. Kempf, G. Manverennorm flYr Schiffe, Hansa, 11.27/28

1944

9.

Norrbin, N.H. On the design and analysis of zig-zag test. Formal Contribution to 10th ITTC 1963

10. Norrbin, N.T1. Zig-hag-Froveta Teknik och Analys.

11

Fig. 2. 10 on the average as defined on r' -

d

_{characteristics.}

stable ship unstable ship

Fig.3. Examples of

r-1

SH/P

-20°

-/0.

MODEL

MODEL

S 0 Al

13

-0.

0.4--O.

-0.8

/ 0°

20°

30'

Fig.4. r'- /Characteristics of a Tanker and Its Model.

a

0 REVERSED

SP/RAL

coRREsea. /.6. CAf

fr

29 0 M

4 8.2

/ 8. 5

Trim

0

Ca

0. 8 35

y7/.7

Vo

/5.5 kt

USUAL

SARAL

A

14

Modern //4

1/451fias

Fig. 5.

Frequency Diagrams for Period Numbers in

10/16

Zig-zag Tests.

/0

/5

20

30

Period NumAer,

5

/0

/5

Period Namher,

(71:

+

)

3 rd.

Fig.6. Course Change Lag as Defined on Zig-Zag Test Record.

3/1/P

0

MODEL-if. 0

/.5

Fig.

7.

Correlation of

Ti

and

T".

'40 /6 20 -24

840 JO /5 25 15

/5

1111a.t

0 0 0 0 8 6 0 9 8 2 0 8 2 A 0 A 0

radder angle / course

viat ion

3750

47/0°

45745°

207200

Fig.8. Statistics'of T Values as obtained from Zig-zag Tests with Different/

_Anglee

Rudder

16 /s

o

Tanker, Full-Loaded

ranker, Ballasted

A

Cargo- Boat, Full-Loaded

A

Carr - Boat, Ballasted

Coast- Ova rd Cutter

_

Typical Examples

Of

T fro/ue

8 8 0 0 8 0 a -k _3o'y".

Ship A

8

C.

1

2.2

1.7

20'

4.2

2.9

3./

/5'

/3

4.3

3.6

/0.

-140

8'.O

2.2

5'

I0

0.5

0.4

0.3

R

0.2

02

_doe

A.

A

WiESPARTIECIr

_..11=111111111'

-.111111C111111PAIMEN

AIN

IMMIIIESIMMEMII1111

iimemondiffilwav

,ERIEV11/1111111.11111=111111

V

X

IPr

111111111111111111

III

11111/20111111111

111111

115626/1111111PMEN

,D11

1111111111111MMINIIR

5°

Amu

WOMIIIEWASE111

ENEN

Nomml

P.:Amara

1111111111111111111MIMPI

SION/1",0-41111111/

1111k9

'

°

)

ENARS111112111

01

Ar.1.7.10'

0

0

PIVPP"

"0

:40"

miini

-dmar1.0Migint

.0-00

4.4I.

Ftw-Ammkgs

/Ail

IES111111

SUM

AMMEI

ZO°Z

3

45

Th"

5-Z

- =

-So

r'.-/401

Fig.9

Statistics

of

Course

Change

Number

P

as

Obtained

from

Zig-Zag

Tests.

0.3

0.4

0.5

3

2

45

A

RUDDER movima TO PORT

RUDDER MOVima TO STARSOARD

0

tc

0-6

FIG. 10. SPMAL FOR DIRECTIONALLY UNSTABLE

CONDMON

SPEED IKNOTS

I_____0

2

_910

10

9

o

s

10

1910.2

(no.'

0 2

0

0 0

EC

0

SO

0

HELM OFF

2S° . .T150. RUDDER

100

SHIP SPEED II KNOTS

Le

PORT RUDDER

200

9

3°STARBOARD

G TIME SECONDS FOR SHIP

RC. I I. PULL OUTS AND WEAVE

h

₀₂

frzoponT0

RECTIONAILLY UNSTABLE CON, DITION

200

0

HELM OFF

o o

e 0

0 w

0

SO

900

ISO

TIME IN SECONDS FO_R SHIP

12TH INTERNATIONAL TOWING TANK CONFERENCE

MANOEUVRABILITY COMMITTEE REPORT

Appendix II

Part 1 Some New Problems and Results Related to Confined

Water Manoeuvring

by Nils H. Norrbin

Part 2 An Outline of Current Studies in Japan on the

Manoeuvrability of Ships in Confined Waters by Seizo Motors

Part 3 Test Techniques and Prediction Methoda

by Nils H. Norrbin

Notes A collection of replies to a Questionnaire on model

experiment activities on confined water manoeuvring will be

included as Part 4 of this Appendix in the printed

proceedings,

Part 1

Some New Problems and Results Related to Confined Water Manoeuvring

by Nils H. Norrbin

1.1. Shipping Trends and New Problems

The history of sea transports on inland waterways is as long as that of boating and shipping itself, and some of the hydro-dynamic problems involved have been competently studied for a centuary now. The high speed wave phenomena dominated the interest of the hydrodynamiciets, whereas ship and canal operators were more concerned about frictional drag increase and bed erosion. Although manoeuvring in shallow water was sometimes discussed before the Tank Leader Conferences in the nineteenthirties this subject should not become essential until

in the late fourties, then in connection with the transit of new twin-screw tankers through the Suez Canal. Finally, to quote from Motora and Pujino in their Appendix to the Manoeuv-rability Committee Report of 1966, /1/, the same problem has become important for huge ocean-going ships such as tankers

as their sizes grew

in relation to the sizes of

harbours and

straits,

In 1967 the typical Suez canal cross-section had an area of

1 800 m2 and a water depth of 15 m above bed, Large tankers

with proven steering qualities were permitted to transit at

a speed of not more than 14 per hour, or 7.5 knots, on a

Fig. 1.1 depicts a 90 000 t.dw. tanker in the canal.

Postu-lating a squat of 0.6 m the underkeel clearance was 2.6 m

roughly, or 22.5 per cent of the draught. This "high" percentage

was likely to prevent excessive erosion due to the back

flow over the bed. (Cf. Part

3,

Section 3.5.)

In

open port approaches the demands for underkeel clearances

are extreemly modest. A "10 per cent of draught" clearance

is often suggested in nautical litterature, although other

authors now indicate individual estimates to fit ship, sea

condition and waterway, /2, 3/. The bottom diagram of Fig.

1.1 illustrates the section of the new 312 000 .t.dw, tanker

in shallow water,

accepting

the 10 per cent clearance. (A.

siiilar diagram of a large tanker in shallow waters was

originally demonstrated by A.F.

Dickson of

the British Oil

Handling Committee.)

The steering properties of a ship have hitherto not been

considered in determining the margin depth required. Yet

it is known that these properties are radically changed with

reduced depth. These chnnges in themselves may introduce

hazards in the control of a ship on the approach from the

sea into the port area. Experimental and theoretical studies

shall be promoted in relation to the hydrodynamics of

navi-gation in these new waterways, where there are usually no

infinitewalltype banks but isolated underwater shoalings, etc.

In Fig. 1.2 'Caere is a blockdiagram indicating the

principle

lines along which manoeuvring problems may be attacked.

The steering simulator technique, inspired by pioneering work in flight training, has made possible a meaningful analysis

of the problems of manual control. A short discussion related to realtime simulation and freerunning model techniques will be found in Part 3, Section 3.8. The "programming" of a simulator requires access to hydrody-namic coefficients derived from captive model tests, or from theory.

The methods of captive testing and analytical modelling are considered in Section 3.7 and 3.8. Some important new experi-mental results are reviewed by Uotora in Part 2 of this

Appendix; of. ref. /4/.

The general flow phenomena are shortly summarized in Section 3.5, but for a detailed discussion the reader is referred to ref. /1/ and to the books by Saunders. (See Part 3, ref. /30/0 A few new theoretical results of special interest are pointed out

in Section 1.3 below.

1.2. Short Review of the ITTC 1966 Survey

In ref. /1/ was presented a general description of the flow distribution around the ship in shallow water and the effects on virtual mass and damping. Special attention was drawn to the unsteady flow phenomena due to bottom pressure drops and

excessive squatting as well as to bank suction and

interaction

between ships.

Upon a survey of available full scale and model steering experiences, and of results from manoeuvring tests and force measurements on models, it was suggested that new experiments should be directed towards a set of well defined problems The theoretical results available were found to be inadequate for handling the threedimensional problems in shallow water as well as in narrow canals.

1,3. Some new results from slender-body theory

The methods of finding hydrodynamic coefficients of ships in manoeuvring motions are mainly experimental, or at most semi-empirical. Corrections for viscous effects may be applied to results from low-aspect wing theory, which in itself includes assumptions as to the viscous lift aft of maximum span.

The main principle of slender-body and low-aspect-ratio wing theory assumes that the differential normal force acting on a transverse element section of the body only depends on the geometrical characteristics of that sane section. The element force may be calculated from the section added mass, which also characterises the strip theory. The application of a strip theory or a slender-body theory is a question of the frequency range considered. The slender-body theory for ships as developed mainly by

Newman and Tuck has proved to give valuable results to guide future work on confined water manoeuvring.

An important feature of ship behaviour in shallow water and canals is the sinkage and trim experienced; indirectly it influences the bottom clearance and boundary conditions to

be applied in oaloulations of transverse forces

on a ship

kept fix in the flow. By use of a first-order 'theory for slender hulls in steady forward motion Tuck has derived simple formulae for the vertieLll forces and for the sinkage and trim at sub- anu s.apercritical speeds in shallow water, /5/. (Cf. Section 5.5.2.) Per small to moderate Proude numbers based on depth sinkage and trim both vary as speed

squared. In

case of ships with fore-and-aft symmetry the theory predicts zero trim for subcritical speeds, and zero sinkage for supercritical speeds.

In a second contribution Tuok has calculated the influence

in the canal to the sinkage (or trim) in shallow water is given by a unique curve on basis of a simple width-and-speed

parameter. It should be remembered, however, that the total

"squat" in a canal is dominated by the contribution from water level lowering as a consequence of flow continuity.

Kan and Hanaoka first presented low-aspect-ratio wing results for the calculation of transverse forces and moments on a ship in oblique or rotational shallow water motion, /7/. As

the theory predicts the same correction factor to

be

applied

to all deep-water values it is essentially a two-dimensional theory. In a recent paper Ilewman points out, however, that the local flow is no longer vertically two-dimensional as in

4

deep water,

/c/o

Part of the transverse flow forms a

two-dimensional outer flow around the waterlines, and thus a three-dimensional effect is introduced. The practical results

are condensed in the diagram reproduced (with additional

symbols) in Fig. 1.3.

The forces acting on a body in close presence of a vertical wall in an otherwise unbounded fluid has also been studied by rewman, /9/. The results are applicable to the case of a ship proceeding at non-wavemaking speed along a wall in deep water. As expected from experience and approximate image theories for bodies not close to the wall there is an attraction towards the wall, increasing monotonically up to a finite

value at body-and-wall contact. It is concluded that for geometrically related bodies with same sectional-area

distribution the suction force will be inversely proportional to the length, whereas the yawing moment will be independent of length variation. The results also indicate that there will be a bow-away-from-wall moment for bodies with a sterr,, which is blunt compared to the bow, and vice versa.

In case of a fullship propelled at moderate speed in a shallow canal the bow will more generally tend to move away from the bank, due to additional effects of bow wave and screw action.

1.4. References (See also Part 2 and Part

3,

Seotion 3.9.)

Note* A bibliography on manoeuvring in confined waters was included in ref. /1/, covering work up to 1965. A detailed bibliography on the whole subject of manoeuv

ring for years

1965

and later has been compiled by

Thieme for the Manoeuvrability Committee Report.

Motora, S., and Fujino, M.: "Brief Survey of the

Manoeuv-rability in Restricted Waters", Appendix 4 of

Manoeuv-rability Committee Report to the 11th ITTC, Tokyo

1966

Hay, D.1 "Harbour Entrances, Channels and Turning Basins",

The Dock and Harbour Authority, Jan.

1968

Forestrbm, R., Asklund, L., and Wahl, G. (ed.)s "Farledere

djupmarginaler" (Waterway Depth Margins), Report by a

Committee to Swedish Board of Navigation, Stockholm,

Dec. 1968

Fujino, M.1 "Experimental Studies on Ship Manoeuvrability

in Restricted Waters, Part I", Intern. Shipb. Progress,

Vol. 15, No. 168, Aug.

1968

Tuck, E.0.: "Shallow Water Flows past Slender Bodies",

Journ. Fluid Dynamics, Vol. 26, Part 10 Sept.

1966

Tuck, E.O.: "Sinkage and Trim in Shallow Water of Finite

Width". Schiftstechnik, 14. Band,

73.

Heft, Sept.

1967

Kane M. and Hanaoka,

T.I

"Analysis for the Effect of

Shallow Water upon Turning", (in Japanese), Journ.

Newman, N.J.: "Lateral Motion of a Slender Body Between

Two Parallell Walls", Prepubl. copy, MIT, Dec.

1968,

to appear in Journ. Fluid Dynamics

Newman, N.J. "The force and Moment on a Slender Body of

Revolution Moving Near a Wall", DTMB Report 2127,

8

90 000 t.dir. tanker in Sues Canal seotion

(1967 conditions)

////77/////////

312 000 t.dw, tanker in shallow water

port approaches

Pig. 1.1. Typical confinements in

large tanker

operations

\Alai er ways

Ships and

Ou41;1 "We sub' 1 Inferpre4a4ion

.711.,

AI.

Services

51.3;p Operw.li'atis I Cor,-Lplex I enu.,...-rer etn

_si

I

.z.,.

CornA.,1 Sita4;cs;

r-act tgnes

Proi,lem

,

Tesiirri

TecAn;if..ors

Hanell;si I i Full Sceae

[

Experin

ece

1

Testifti

1"7

;

1

4,4e! Te sivsely

Pr1rL pje iires

SAira 0..141 !1*.lci

' Full 5.

Correi.eLi;on F'r.e.dt'cAions

Full ge.tie

Tesf

Eve:L1444d.

!Ship aft4Tlies7!

Correia-lion

1 ;Made) et....1Titea7i Corr,1441;ew

1.0 0 2.0 Legend: A 21,

6

.

i P Pi 2 3 4 10 1.5 Product A

pi

o

0.5 0.1 0.2 1 I 1

Fig. 1.3. Shallow-water effect on

transverse

forces for a flat-plate hull moving

at

non-,wavemaking forward speed

(Lateral motion between two parallell walls,

Newman, 1960

Part 2

An Outline of Current Studies on the Manoeuvrability of Ships in Restricted Waters in Japan

by

Seizo Motora

In this report, the reporter summarizes theoretical and experimental studies on the manoeuvrability of ships in restricted

waters in Japan, and are much indebted to the paper "Manoeuvrability

on Shallow Water" published by Y. Yamanouchi and N. Mori in

1968 (1).

1. Theoretical Studies

Assuming that the advance speed of ship is, in general, so small in shallow water that the phenomenon of wave making is negligible with respect to the manoeuvrability of ships, M. Kan

and T. Hanaoka calculated approximately the effect of finite water

depth on the turning ability of ships (2).

According to it, the effect of shallow water on the hydrodynamic force and moment generated by drifting or turning

motions are represented by the coefficient kF which means the

ratio of the hydrodynamic force or moment at certain water depth

H to those at infinite water depth.

kir =

4E1 f0/

_SA.-1(

7/1/2't) 617

where Z= H/d

( water depth/draft of ship )

With respect to the rudder force, similar coefficient

k is also introduced in the same way as the wall effect of wind tunnel to the lift of wing.

=

-t 2

k

r)/A.

4.2)011.-c7-)A.

where

: aspect ratio

2Z-44, :

lift coefficient effective attack angle

T :

dependent of aspect ratio ( for instance 7#0.13,

in case of A.4 )

The values kF and kg are calculated and plotted in Fig. 1.

2. Experimental Studies

2.1. Experiments on free running models

Some of the experiments with self propelled models are introduced in this section.

Fig. 2 and 3 show the test results of turning ability conducted at Ship Research Institute with variation of water depth

and rudder area. The prototype of the models used are a large oil tanker and a normal cargo ship. The abscissas of these figures are

e

rudder angle

0t

and the ordinates are non-dimensional turning rate

T' ( ship's length/steady turning radius )(3).

In Fig. 4 and 5, similar test results are shown of a large oil tanker with single screw and twin screws, which were conducted at Technical Research and Development Center of Defence Agency (4).

Fig. 6 - 8 are similar test results of a large oil tanker at Kyushu University (4).

In order to distinguish the effect of finite water depth on turning ability, the test results of Fig. 2 and 3 are rearranged

and shown in Fig. 9, where the ratios of turning rate ro

at

certain water depth H to turning rate r at infinite water depth

are plotted on the H/d basis. Similarly, Fig. 4 -8 are also

rearranged and summarized in Fig. 10.

2.2. Experiments with constrained models

In the rotating arm basin of Ship Research Institute,

the hydrodynamic force and moment acting on the naked hull of

the model of a large oil tanker were measured in shallow water

and deep water with variation of drift angle and yaw angular

velocity r. The test results are shown in Fig. 11, where the

hydrodynamic force is non-dimensionalized by dividing by 11-11,2'lll

(5).

Similarly using the model of an ore carrier of Great Lakes, the hydrodynamic force and moment in shallow water (H/d

1.36) were measured with forced yawing technique by the

author, and some of the results are shown in Fig. 12 and 13 (6).

In these figures, the test results in deep water are also shown

for the purpose of comparison with shallow water test data.

In Fig. 14 are shown the results of the spiral test of an ore carrier "Benjamin Fairless" of Great Lakes, for both

shallow water (H/d 1.36) and deep water (6).

The course stability of ships are determined by the relative positions of the points of application of sway damping

force and yaw damping force, Then, in order to Investigate the

course stability in shallow water, the point of application of

R,

sway damping force 44( - N, TY;; ) and yaw damping force

lc(

/(-(mu ) _sf;,. ) were measured by forced yawing

technique by Fujino. The test results are shown in

Fig. 15 - 18, of which Fig. 15 and 16 give the results of the

Mariner type ship and the remains are those of an oil tanker

"Tokyo Maru" (7).

In 1964 - 1966, the bodily sinkage of ships in shallow

water were measured at Kobe University of Mercantile Marine, and one example of them is shown in Fig. 19 (8).

2.3. Shallow water effect on lateral resistance and turning moment In case of handling large ships in ports or shallow bays It comes into question to what extent the lateral resistance and turning moment required to bring the ship to the prescribed position, are affected by finite water depth.

To solve this problem, a 3m model of a large oil tanker was towed by the towing carriage with drift angle 0.- 180"and the

lateral force and turning moment were measured in various cases of water depth at Ship Research Institute (9).

The results are shown in the form of lateral force coefficient Cy ( = Y/if1J2Ld ) and turning moment coefficient

Ck ( - Niffu2LId ) in Fig. 20 and 21 respectively. The points

of application of the resultant hydrodynamic force are shown in Fig. 22, where " a " stands for the distance from the point of application to F.P..

In Fig. 23, the ratio k of the lateral force at finite water depth to that at infinite depth is shown in case of open water and in case where the quay wall exists, where " s " means the distance between the quay wall and the ship as shown in the

figure and " B " Is the breadth of ship.

2.4. Effect of restricted width on the maneuverability

Fujino(7) conducted an extensive experiment on the hydro-dynamic force and moment acting on a model navigating through a channel varying its width and depth. Forced yaw technique making use of a planer motion mechanism was employed. Therefore, effect of restricted width on the added mass, added mt. of inertia,

linear derivatives and rotary derivatives as well as the aspmnetric side force and moment were obtained. Fig. 24 is an example of

measured side force and moment acting on a Mariner ship model

navigating offset position of a channel. Fig. 25, and 26 are measured rotary derivatives of the same model. Using these

derivatives, it was found that the Mariner ship model which is marginally stable in deep water tends to be very unstable in a

channel, even the channel width is fairly large. Ship's behavior in a channel with an initial yaw angle is calculated as shown in Fig. 27 where

0'

is the angle of yaw and Is the offset distance /ship's length.

It was also shown that this directional instability In

a channel can be easilly overcome by applying a simple automatic

control by yaw angle deviation as shown in Fig. 28.

REFERENCE

Yamanouchi, Y. and Mori, N.: " Manoeuvrability on Shallow Water " The Nautical Society of Japan,

1968.

Kan, M. and Hanaoka, T.: " Analysis for the Effect of Shallow Water upon Turning " Journal of Zosen Kiokai, vol.115,

1964.

Koseki, N., Yamanouchi, Y., Matsuoka, S. and Yamazaki, Y.: " Some Model Experiments on Shallow Water Effects upon Turning Ability " Journal of Zosen Kiokai, vol.117, 1965. The Shipbuilding Research Association of Japan: " Experimental Studies on Navigation of Large Ships " ( translated from Japanese title ) Report of Research Section No.

98.

1968.

Mort, N.: " Studies on Shallow Water Effects by Constrained

Models " ( translated from Japanese title ) Unpublished. Motora, S. and Couch, R.B.: " Manoeuvrability of Full Bodied

Ships in Restricted Waters " SNAME, Great Lakes and Great Rivers Section,

1961.

Fujin°, M.: " Experimental Studies on Ship Manoeuvrability

in Restricted Waters " 'SP vol.168, 1968 JOUrnal of Zosen Kiokai, vol. 124, 1969

Kobe University of Mercantile Marine: " Studies on the Bodily Sinkage of Ships in the Inland Sea of Japan " ( translated

from Japanese title ) Report I, II, III.

1964 - 1966.

The Japan Dredger Technical Society: " Report of Research

and Investigation into Tag Boat for Large Ships ( translated from Japanese title )

1968.

2.0 1.3 1.6 1.4 1.2 1.0 1.0 1.4

Fig.1

The Coefficients kF ctind ka Versus the i4atio of water

depth

to

sh;p's

draft

%

(a)

awin

nal/

E 11,1

vand

/20

la

b9z

w

izoz

*o

zaOQOçfr

7

LZSI

ON 'kV 0 .0

inwritirmitgawidi

_:

_.1-

_ono

_.1

_c

gm

rams

.7., vo- .., .., IV

r

Lid H . Q2 l'..- ... 0

MINI

.0,,

..

(s)

z.o .01 OF

w

,OZ .01

0r.0z

.ot

r

.0Z .

.,t_.0,z_hi

.o,_._

MEM

ro

p 0 -, ',I,

.0,,,,_

1

t

v ts, r u j_r____I 91 OSI '0

,

,4, . . PL '91 HZ .1 'II 08/1I

/

' _Pv

xi

I'

uL9/1

px1 NV

V

09/ Px"1/14V 9' 0 %00I V O/-O9/ 1 p x 1/ .v (PZZ 1-1) 01 0 1 El 0 LZSI ON 'IV

M . NO

30

4.5000 pz

o. 6/66M

0. 2466 in

0. 70

479.# 1,

Fig'.

3.

r!-- er carve in

Shallow water

( 9 ) 0.8 0.6 0.4 0.2 M, NO 30 1/60 /Lxd A 100% Trim 0% H. 1. 23d-18. 2d Fn 0.20

10'

,

-40'

30'

.5.(P.)

/

---20

....,

/o.

1

/

/I

-

0.2

' 6. 20' 30' 4 ' S.) .., ... ,.. ca. A [ MARK

-- ,....e-1 -0.6 3. 66d

.(----2.40d 1,77d

---.--- ---",----_0. 8_______+, I. 36d

--c

1.23d

-(01)

71d,1

2:0

7'0

CS) C

)

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x/x

Fig

.

5.

S" curve

in

Shallow

water

4.5 0 0 0 M

B

0.1

62 M

d

0.2 6 7

4 M.

L/1?)

5.5

B/d

3.0 6

in, GB s

0. 8 4

AR

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1/70

Fri

0.13

No OF PROP 2

(5) 02

St(p.)

40° ,30° 20° ¶ 0° 0° 20° - 30° 40° Sr (S.) 9.0 0$? 0.6 04 -0.2 04-0.6 -1.0

r,

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F;g. 6.

r-i" carve in

Shallow Water

(12)

L 2S 0 0 0 8 0.4 5 4 S d O. 4 S S %-/0 0/d 3.0 G I 3 S. 0 Ca O. S 0 Fn

A. Ld i/70

-40'

-30.

-20e

curve

in

Shallow

water

J.

2 5 0 0 0 M.

0.5 0 0 OM

d

_{0.16 3 Z M.}

LIB

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/3/c1

3.06

A

1

6 3.4 K_g_

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0.80

Atkkd

1/70

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0.1 3

H/cl

6 2.

---.---2

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0

(6)

1.0 0.6

0.6

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2.5

2

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r-'-er carve in sha.itow

water-( 14) I 1 I 1 10°

20°

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400

s(S)

L

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1 6_8 Nit

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FY,

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(P.)

( S. ) -100 -90 100 80 I 90 -70

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8

80 60 LI

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10

2.0

J.

CARGO

S.401

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S.30.

S. 2(Y

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\P.3.5.1

Tycrf VESSEL (SCHMIDT)

P:25CARGO

TANKER

P.40"

THEORETICAL VALUE (MAN AND HANAOKA)

F,0 9

Shallow ,f'r.ter e-f-f7ct on, turrine-

rate

(15)

CARGO TANKER itiL X (1 1/60 1/67.2 A 100% 100% TRIM 0% 0% Fn 0.20

30

4.0

5.0

6.0

Hid

100

90

80

70

60

50

40

F;.10.

shallow water

effect on tarn;nq rate

,

,

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---.---/

...,

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i

/,,...

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S -.353

.

0

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fl

1.0 _2.0

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25

0

50

M.NO 92

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SHALLOW

40

WATER

A

y'xio3

7

DEEP

7

WATER

o

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0

20

o.,

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0.25

rf

0.38

Fig. 11. non-dimensional hydrodynamic -force ;n Shallow and

deep

Water

(17)

)

H/

1 1.5

12 .3

U

0.4 5 ras 0.60 m/s

0--10

Vq) lc?

5.0 4.0 3.0 2.0 1.0

DIFT ANGLE.CP) /3

-5°

-10 ._110.5

-2.0

-3.0

-4.0 _22.0

14/(1 ) x103

2.5

2.0 1.5 1.0 0.5

-1.0

-t5

sLY%/

14Y-1

Fig. 42. non-dimens;onai hydrodynamic corce and

moment

in Shallow and deep water (

= 0)

DRIFT ANOI-E(a)

( 18) SHALLOV WATER

(1.33d)

DEEP WATER 1 00. 5 c.)

V 1

-

nirs+Y(r)p10 Ner) 1 03

10

12.0

1.5

5

f1.0

0.5

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- 0.2

-0.1

0.5

0.1

0.2

.0.3

0.4

0.5

..7i I

I-`Pf(S) Y`-DEEP WATER NJA

Fig. 130 non-dimensional hydrodynamic force and moment

lit Shallow and

_{deep wo.ter (13=0 )}

O STARTED FROM THE

RIGHT. HELM

STARTED FROM THE

LEFT HELM

-200

-0.4

-0.6

(20)

1 100 20° 1

RUDDER ANGLE

g" i I

RIGHT

Fig. 14. ResuitS of Spiral

test ;n deep and

Sinflow

Water

L

6 2 2'

9"

'5

67,

0'

d

2 4'

O"

L/3

9.3 0

B/d

2.7 9

2 3,9 G OLT

F19. 15.

Shallow

Water effect on I,,E4

Mariner type ship

(Fn. 0.0905)

(21)

\

\

\

0.1)...

ii.

,

,..,...

----IMO.. IMM

if - : H S 00

IIIM110 IN a

i '

_{A *}.

H-

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1.0

1.5

,

2.0

2.

I-1/d

\

iif

. __ J

1.0

2.0

1.0

05

01

1.5

2.0

Ay.f6. Shallow water eject on

J

.4;

Mariner

type Ship

( Fn = o. /55 )

OMNI= 411=.1. MOM YEN. MN.

z

16ii Co)

(22)

0 01.100.0.000.00, ammoonsam...

H

00