ISO 13643-3:2017

INTERNATIONAL ISO
STANDARD 13643-3
Second edition
2017-02
Ships and marine technology —
Manoeuvring of ships —
Part 3:
Yaw stability and steering
Navires et technologie maritime — Manoeuvres des navires —
Partie 3: Stabilité en lacet et pilotage
Reference number
ISO 13643-3:2017(E)
©
ISO 2017

---------------------- Page: 1 ----------------------
ISO 13643-3:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 13643-3:2017(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test-related physical quantities . 2
5 General test conditions . 5
6 Test 3.1 — Pull-out test . 6
6.1 General . 6
6.2 Analysis and presentation of results of a pull-out test . 6
6.3 Designation of a pull-out test . 7
7 Test 3.2 — Direct spiral test (according to Dieudonné) . 7
7.1 General . 7
7.2 Description . 7
7.3 Analysis and presentation of results of a direct spiral test (according to Dieudonné) . 8
7.4 Designation of a direct spiral test (according to Dieudonné) . 9
8 Test 3.3 — Reverse spiral test (according to Bech). 9
8.1 General . 9
8.2 Description .10
8.3 Analysis and presentation of results of a reverse spiral test (according to Bech) .10
8.4 Designation of a reverse spiral test (according to Bech) .11
9 Test 3.4 — Weave test .12
9.1 General .12
9.2 Description .12
9.3 Analysis and presentation of results of a weave test .13
9.4 Designation of a weave test .13
10 Test 3.5 — Astern test .13
10.1 General .13
10.2 Description .14
10.2.1 Description of the direct astern test .14
10.2.2 Description of the astern zig-zag test .14
10.3 Analysis and presentation of results of an astern test .15
10.3.1 Analysis of a direct astern test .15
10.3.2 Analysis of an astern zig-zag test .16
10.4 Designation of an astern test .16
10.4.1 Designation of a direct astern test .16
10.4.2 Designation of an astern zig-zag test .16
11 Test 3.6 — Sine test .16
11.1 General .16
11.2 Description .17
11.3 Analysis and presentation of results of a sine test .17
11.4 Designation of a sine test .19
Bibliography .20
© ISO 2017 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 13643-3:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www . i so .org/ iso/ foreword .html.
The committee responsible for this document is ISO/TC 8, Ships and marine technology, Subcommittee
SC 6, Navigation and ship operations.
This second edition cancels and replaces the first edition (ISO 13643-3:2013), of which it constitutes a
minor revision with the following changes:
— the numbering has changed;
s-1 -1
— in Clause 4, Table 1, the SI-Unit in first line was changed from “rad ” to “rad s ”;
— in the second line of 9.4, “δ = 10° (10)” was changed to “δ = −10° (10)”.
Ri Ri
A list of all parts in the ISO 13643- series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 13643-3:2017(E)
Ships and marine technology — Manoeuvring of ships —
Part 3:
Yaw stability and steering
1 Scope
This document defines symbols and terms and provides guidelines for the conduct of tests to give
evidence about the yaw stability and steering of surface ships, submarines, and models. It is meant to be
read in conjunction with ISO 13643-1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 13643-1:2017, Ships and marine technology — Manoeuvring of ships — Part 1: General concepts,
quantities and test conditions
ISO 13643-5:2017, Ships and marine technology — Manoeuvring of ships — Part 5: Submarine specials
ISO 80000-1, Quantities and units — Part 1: General
ISO 80000-3, Quantities and units — Part 3: Space and time
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp/
3.1
astern test
manoeuvring test to determine the ship’s ability to maintain course while making way astern
3.2
astern zig-zag test
manoeuvring test to determine the ship’s ability to maintain course while making way astern by
assessing manoeuvring devices efficiency from a zig-zag test
3.3
direct astern test
manoeuvring test to determine the ship’s ability to maintain course when making way astern using its
manoeuvring devices and tunnel thrusters as available
3.4
direct spiral test (according to Dieudonné)
manoeuvring test to determine the yaw stability and turning ability when using constant manoeuvring
device settings
© ISO 2017 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO 13643-3:2017(E)

3.5
manoeuvring device
rudder, azimuthing thruster, hydroplane, cycloidal propeller, or equivalent system used to manoeuvre
a vessel
3.6
pull-out test
manoeuvring test for quick determination of a ship’s yaw stability related to its speed through the water
3.7
reverse spiral test (according to Bech)
manoeuvring test to determine the yaw stability and turning ability when using constant yaw rates of
turn
3.8
sine test
manoeuvring test to determine the ship’s turning and yaw-checking ability in relation to initial speed
and manoeuvring device settings for the purpose of setting up auto pilots
3.9
weave test
manoeuvring test to determine the extent of a ship’s potential yaw instability
4 Test-related physical quantities
Test-related physical quantities are listed in Table 1. The more general quantities and concepts
concerning the manoeuvring of ships are set out in ISO 13643-1.
For quantities and their units, ISO 80000-1 and ISO 80000-3 shall be used.
Table 1 — Test-related physical quantities
Symbol CC- SI-Unit Concept
Code
Term Definition or explanation

dψ 
Gradient of the ψ (δ )
C
-1 CRi
GRDNTD s —
dδ curve at δ
0
Ri
-1
GRDNTB s —
 
dψ Gradient of the ψ (δ )
i iR
curve at δ
0
dδ
R
L L m Length Reference length of a ship (see ISO 13643-1)
a
l LWRD rad Loop width For a ship with yaw instability: measured
δ

between the two extremes of the curve δ ()ψ
R
-1 b
LHRD rad s Loop height For a ship with yaw instability: measured

lψ

between the intersections of the ψ(δ ) curve
R
with the axis δ = 0
R
-1
n NI s Test propeller speed —
i
P/D PDR 1 Pitch ratio —
P PITCHI m Test propeller pitch Propeller pitch given relative to the pitch for
i
zero thrust at zero speed
a
For angles, the unit ° (degree) may be used.
b
For rate of turn, the unit °/s (degree per second) may be used.
c
The unit kn, common in navigation, may be used.
2 © ISO 2017 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 13643-3:2017(E)

Table 1 (continued)
Symbol CC- SI-Unit Concept
Code
Term Definition or explanation
T TIP s Period of manoeuvring Specified time to move the manoeuvring device,
device oscillation e.g. from the specified amplitude to starboard
(S) to the same amplitude to port (P) and back to
the specified amplitude to starboard (S)
st
t TIC1 s First time to check yaw Elapsed time from initiating 1 application of
C1
manoeuvring devices in the opposite direction
until maximum change of heading is reached
nd
t TIC2 s Second time to check yaw Elapsed time from initiating 2 application of
C2
manoeuvring devices in the opposite direction
until maximum change of heading is reached
t TIF s Course keeping time Time during which the ship maintains course in
F
accordance with 10.2.1
-1 c
V VF m s Final speed Speed at the end of test (run)
F
-1 c
V VI m s Target speed Speed corresponding to propeller speed/pitch
i
setting on straight track
-1 c
V V0 m s Initial speed (See ISO 13643-1)
0
x X0 m — Coordinate in the direction of the initial heading
0
of the earth-fixed axis system moving with
the water, the origin of which coincides with
that of ship-fixed axis system at t = 0 (see also
ISO 13643-1)
x X0F m Sternboard x -component (astern) of the ship’s track at t
0F 0 F
y Y0 m Transverse axis Coordinate of the earth-fixed axis system in
0
water surface perpendicular to x , analogous
0
definition (see also ISO 13643-1)
y Y0F m Transfer at end of test y -component of the ship’s track at t
0F 0 F
(run)
z Z0 m Vertical axis Coordinate of the earth-fixed axis system or-
0
thogonal to x and y , vertically down, analogous
0 0
definition (see also ISO 13643-1)
Δz DZ0F m Change of dived depth z -component of the ship’s track at t , relative to
0F 0 F
the value at the commencement of a test (run)
a
Δδ DANRUI rad Manoeuvring device —
Ri
angle step
a
Δψ DPSIH rad Change of heading ψ – ψ
0
a
Δψ DPSIHE rad Execute change of heading Specified absolute amount of change of heading
E
for applying the manoeuvring devices into the
opposite direction
a
Δψ DPSIHF rad Change of heading at end ψ – ψ
F F 0
of test
a
Δψ DPSIHM rad Maximum change of —
MAX
heading
-1 b
DYARTC rad s Difference between final Resulting from S and P turns at the same V
0

Dψ
C
asymptotic rates of turn
a
δ ANRUA rad Manoeuvring device angle If necessary, an equivalent manoeuvring device
Ra
amplitude amplitude shall be given, e.g. for submarines
with X-planes: ¼ (δ + δ − δ − δ ).
Aa2 Aa3 Aa1 Aa4
a
For angles, the unit ° (degree) may be used.
b
For rate of turn, the unit °/s (degree per second) may be used.
c
The unit kn, common in navigation, may be used.
© ISO 2017 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO 13643-3:2017(E)

Table 1 (continued)
Symbol CC- SI-Unit Concept
Code
Term Definition or explanation
a
δ ANRUI rad Test manoeuvring device Relative to δ
Ri 0
setting
If necessary, an equivalent test setting shall
be given, e.g. for submarines with X-planes:
¼ (δ + δ − δ − δ ).
Ai2 Ai3 Ai1 Ai4
a
δ ANRUI1 rad First test manoeuvring Relative to δ
Ri1 0
device setting
To which the manoeuvring devices are put at
the commencement of the test. If necessary, an
equivalent test setting shall be given, e.g. for
submarines with X-planes:
¼ (δ + δ − δ − δ ).
A2 A3 A1 A4
a
δ ANRUI2 rad Second test manoeuvring Relative to δ
Ri2 0
device setting
st
To which the manoeuvring devices are put at 1
counter setting. If necessary, an equivalent test
setting shall be given as for δ .
Ri1
a
δ ANRUI3 rad Third test manoeuvring Relative to δ
Ri3 0
device angle
nd
To which the manoeuvring devices are put at 2
counter setting. If necessary, an equivalent test
setting shall be given as for δ .
Ri1
a
δ ANRU0 rad Neutral manoeuvring (See ISO 13643-1)
0
device angle
a
ANRUM rad Mean manoeuvring de- Determined in each stage of the test during a pe-
δ
R
vice angle riod of sufficiently constant ship’s speed through
the water and rate of turn
a
ε EPH rad Phase shift Between heading and manoeuvring device angle
a
θ TRIMSF rad Trim angle at end of test —
SF
a
θ TRIMSM rad Maximum trim angle —
SMAX
a
θ TRIMS0 rad Initial trim angle —
S0
a
ψ PSIH rad Heading (See ISO 13643-1)
a
ψ PSIHE1 rad Heading for first execute ψ + Δψ
E1 0 E
Heading when the manoeuvring devices are ap-
plied in the opposite direction (turn to P)
a
ψ PSIHE2 rad Heading for second exe- ψ − Δψ
E2 0 E
cute
Heading when the manoeuvring devices are ap-
plied back in the original direction (turn to S)
a
ψ PSIHF rad Final heading Heading at the end of a test (run)
F
a
ψ PSIS1 rad First overshoot angle During the turn, angle between the heading at
S1
which the manoeuvring devices are applied in
the opposite direction and the heading at which
the vessel ceases to turn in the current direction
a
ψ PSIS2 rad Second overshoot angle During the turn, angle between the heading
S2
at which the manoeuvring devices are applied
back in the original direction and the heading
at which the vessel ceases to turn in the current
direction
a
For angles, the unit ° (degree) may be used.
b
For rate of turn, the unit °/s (degree per second) may be used.
c
The unit kn, common in navigation, may be used.
4 © ISO 2017 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 13643-3:2017(E)

Table 1 (continued)
Symbol CC- SI-Unit Concept
Code
Term Definition or explanation
a
ψ PSIHA rad Amplitude of heading Amplitude of the heading resulting from the si-
a
nusoidal oscillation of the manoeuvring devices
a
ψ PSIH0 rad Initial heading Heading of a vessel at the commencement of a
0
test (run)
-1 b
YART rad s Rate of turn —

ψ
-1 b
YARTA rad s Amplitude of rate of turn Amplitude of the rate of turn resulting from the

ψ
a
sinusoidal oscillation of the manoeuvring devices
-1 b
YARTC rad s Constant rate of turn Mean value of the rate when the ship has reached

ψ
C
steady conditions after each change of manoeu-
vring device setting
-1 b
YARTCP rad s Asymptotic rate of turn To which the ship pulls out in P turn

ψ
CP
(for P turn)
-1 b
YARTCS rad s Asymptotic rate of turn To which the ship pulls out in S turn

ψ
CS
(for S turn)
-1 b
YARTI rad s Test turning rate Required rate of turn for a stage of the test

ψ
i
-1 b
ω OMF rad s Angular frequency 2π/T
a
For angles, the unit ° (degree) may be used.
b
For rate of turn, the unit °/s (degree per second) may be used.
c
The unit kn, common in navigation, may be used.
5 General test conditions
The general test conditions in ISO 13643-1:2017, Clause 8 shall be observed.
When operating submerged, submarines shall be trimmed according to the results of the neutral level
flight test in ISO 13643-5:2017, Clause 8. During the test, the dived depth shall be kept as constant as
possible. The dived depth and the plane angles are to be recorded continuously. If the submarine is
equipped with planes acting into the horizontal as well as into the vertical direction at the same time
(e.g. X-planes), these planes should be controlled in such a way that the dived depth is maintained with
priority.
During the test, including the approach phase, each successive position of the ship is to be recorded —
e.g. using an onboard navigation system during surface operations — at suitable time intervals (usually
every second).
The reference point on the vessel from where its track is measured should be defined in advance (e.g.
location of a positioning system antenna). This point is not necessarily identical with the origin of
the ship-fixed axis system for which the vessel’s track is given (see ISO 13643-1). Data which are to
be recorded continuously include (but need not be limited to) manoeuvring device angle of operation,
power setting, speed through the water, heading, rate of turn, angle of heel, propeller shaft speed/torque,
propeller pitch, true wind velocity and direction, and relative wind velocity and direction.
© ISO 2017 – All rights reserved 5

---------------------- Page: 9 ----------------------
ISO 13643-3:2017(E)

6 Test 3.1 — Pull-out test
6.1 General
In addition to the general test conditions outlined in ISO 13643-1 and Clause 5, the following conditions
shall be complied with.
— The ship shall approach on a steady heading and at a constant speed, V , before commencing the
0
test. During the test, the propulsion plant settings shall remain unaltered.
— The ship is put into a steady turn, which is outside the expected range of yaw instability, e.g. with a
test manoeuvring device setting δ of at least 20° to either P or S. The description is for a turn to S.
Ri
— When the rate of turn and the speed of the ship have become constant, the manoeuvring device is
returned to amidships (zero-position) and held there until the rate of turn again reaches a sufficiently

steady final asymptotic value, ψ . Heading, manoeuvring device setting, and propeller speed/pitch
CS
are to be recorded continuously. The test comprises a second run turning in the opposite direction.
If the ship is stable in yaw, the rates of turn for alterations to both P and S will decrease to the same
residual rate of turn (not necessarily zero); if the ship is unstable, the residual rates of turn will differ.
The individual runs of the test may be conducted after corresponding turning circle tests (see
ISO 13643-2:2016, Clause 6).
Key
1 ship unstable in yaw
2 ship stable in yaw
3 manoeuvring device back to zero
Figure 1 — Pull-out test
6.2 Analysis and presentation of results of a pull-out test
The following data are obtained from the test:
6 © ISO 2017 – All rights reserved

---------------------- Page: 10 ----------------------
ISO 13643-3:2017(E)

—  difference between asymptotic rates of turn

Δψ
C
—  asymptotic rate of turn (for starboard turn) 
ψ
CS
—  asymptotic rate of turn (for port turn) 
ψ
CP
The time histories of the rates of turn for a pair of S and P turns with identical initial speeds are plotted

in the same diagram. The difference between the final asymptotic rates of turn, Δψ , indicates the
C
degree of yaw instability.
If the assessment of the range given by the residual values for the S and P rates of turn proves the
ship to be unstable, consideration should be given to conducting either a weave test (see Clause 9) or a
reverse spiral test (see Clause 8), taking into account the residual values for the S and P rates of turn.
6.3 Designation of a pull-out test
Designation of a pull-out test according to ISO 13643-3, (3), Test 1 (1), carried out with an initial speed
of V = 18 kn (18) and a test manoeuvring device setting δ = 20° (20):
0 Ri
Pull-out test ISO 13643 − 3.1 × 18/20
7 Test 3.2 — Direct spiral test (according to Dieudonné)
7.1 General
In addition to the general test conditions outlined in ISO 13643-1 and Clause 5, the following conditions
shall be complied with.
— The direct spiral test consists of several steps performed in succession. The individual steps are
performed using different manoeuvring device settings which shall be kept constant during each step.
— To minimize the time needed for the test, the results of the turning circle tests (see ISO 13643-2)
should be considered in advance in order to avoid repetition of tests at specific manoeuvring device
settings and rates of turn.
7.2 Description
The ship shall approach on a steady heading and at the specified speed, V , before commencing the test.
0
During the test, the setting of the propulsion plant remains unaltered.
The manoeuvring devices are put to starboard (S) at a test manoeuvring device equivalent δ = −20°
Ri
and held in this position until rate of turn and speed are constant.
The manoeuvring device setting, δ , is then successively decreased to −15° (S), −10° (S) and again held
Ri
at each setting until constant speeds and rates of turn are obtained.
In the range δ = −10° (S) to +10° (P), the test manoeuvring device setting should be decreased in steps
Ri
of, e.g. Δδ = 2°. When moderate yaw instability is expected, the test manoeuvring device setting, δ ,
Ri Ri
should be decreased in steps of Δδ = 1°, in the range δ = −5° (S) to +5° (P). Beyond δ = +5°, steps
Ri Ri Ri
should be increased again.
Manoeuvring device setting, rate of turn, heading, ship speed through the water, and/or propeller
speed/pitch shall be recorded continuously.
After the test manoeuvring device setting δ = 20° (P) has been reached, an initial evaluation of the
Ri
test results is made. When yaw instability (see 7.3) is observed, the test shall be continued by reversing
the process from a manoeuvring device setting δ = +20° (P) to −20° (S).
Ri
© ISO 2017 – All rights reserved 7

---------------------- Page: 11 ----------------------
ISO 13643-3:2017(E)

If the test procedure is interrupted, it is important to recommence it using a manoeuvring device angle
inducing the same direction of turn as before the interruption.
7.3 Analysis and presentation of results of a direct spiral test (according to Dieudonné)
The following data are obtained from the test:
 
—  gradient of the ψ(δ ) curve at δ dψ
0
R C
dδ
Ri
—  loop width l
δ
—  loop height
l

ψ
—  neutral manoeuvring device angle δ
0

The mean constant turning rates, ψ , during the constant phase of each step are plotted against the
C
test manoeuvring device setting, δ .
Ri
The tendency of the measured rates of turn, particularly for small manoeuvring device angles, indicates
the ship’s yaw stability. The ship is stable in yaw if the results indicate a continuous curve and the

gradient of the rate of turn, ψ ()δ , at the intersection with the δ -axis is negative (see Figure 2) or,
Ri
CRi
in the limit, infinite. If the trend of the results indicates the existence of two separate “branches” of the
curve (see Figure 3), then the ship is unstable in yaw. The extent of the region of yaw instability (loop)
defined by the height and the width of the discontinuity is a measure for the yaw instability.
For ships stable in yaw, the test yields the neutral manoeuvring device angle, δ .
0
Figure 2 — Ship stable in yaw
8 © ISO 2017 – All rights reserved

---------------------- Page: 12 ----------------------
ISO 13643-3:2017(E)

Key
a
Change of manoeuvring
...