EN ISO 8728:1998
(Main)Ships and marine technology - Marine gyro-compasses (ISO 8728:1997)
Ships and marine technology - Marine gyro-compasses (ISO 8728:1997)
2012-06-07 EMA: In accordance with resolution BT 65/2007, this standard has been withdrawn further to ISO decision to launch a revision.
Schiffe und Meerestechnik - Kreiselkompasse für die Seeschiffahrt (ISO 8728:1997)
Diese Internationale Norm legt die Konstruktion, die Leistungs- und Typprüfung für die in Kapitel V von SOLAS 1974 geforderten Kreiselkompasse fest.
Navires et technologie maritime - Compas gyroscopiques à usage marin (ISO 8728:1997)
Ships and marine technology - Marine gyro-compasses (ISO 8728:1997)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2000
Ships and marine technology - Marine gyro-compasses (ISO 8728:1997)
Ships and marine technology - Marine gyro-compasses (ISO 8728:1997)
Schiffe und Meerestechnik - Kreiselkompasse für die Seeschiffahrt (ISO 8728:1997)
Navires et technologie maritime - Compas gyroscopiques a usage marin (ISO
8728:1997)
Ta slovenski standard je istoveten z: EN ISO 8728:1998
ICS:
47.020.70 Navigacijska in krmilna Navigation and control
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
IS0
INTERNATIONAL
STANDARD
Second edition
1997-06- 15
Ships and marine technology -
Marine gyro-compasses
- Compas gyroscopiques B usage marin
Navires et technoiogie maritime
Reference number
IS0 8728: 1997(E)
IS0 8728: 1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 8728 was prepared by Technical Committee
lSO/TC 8, Ships and marine technology, Subcommittee SC 6, Navigation.
This second edition cancels and replaces the first edition (IS0 8728:1987),
which has been technically revised.
Annex A forms an integral part of this International Standard. Annex B is for
information only.
0 IS0 1997
All rights reserved. Unless otherwise specified, no par? of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
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Printed in Switzerland
ii
INTERNATIONAL STANDARD @ IS0 IS0 8728:1997(E)
Marine gyro-compasses
Ships and marine technology -
1 Scope
This International Standard specifies the construction, performance and type testing for gyro-compasses required by
Chapter V of SOLAS, 1974.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
ISO/R 694: 1968, Positioning of magnetic compasses in ships.
IEC 9451994, Marine navigational equipment - Genera/ requirements - Methods of testing and required test
results.
International Convention on Safety of Life at Sea (SOLAS) 1974 (amended).
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 gyro-compass: Complete equipment including all essential elements of the complete design.
3.2 true heading: Horizontal angle between the vertical plane passing through the true meridian and the vertical
plane passing through the ship’s fore-and-aft datum line; it is measured from true north (000”) clockwise through
360°.
When the gyro-compass equipment is not installed on board ship, this “true heading” is regarded as the true heading
NOTE -
of the lubber line. Where a gyro-compass has the facility of introducing a correction by moving the lubber line, the correction is
set for the local latitude.
3.3 settled: Stable situation when any three readings taken at intervals of 30 min are within a band of 0,7”, with
the compass level and stationary.
The settling time is the elapsed time between the time of switch-on at the initial heading error and the third recording
NOTE -
of the settle.
3.4 settle point heading: Mean value of ten readings taken at 20 min intervals after the compass has settled as
defined in 3.3.
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IS0 8728:1997( E)
settle point error: Difference between the settle point heading as defined in 3.4 and the true heading.
3.5
error: Difference between the observed value and the settle point heading as defined in 3.4.
3.6
3.7 bearing repeater compass: Device that reproduces the master compass card at a remote location.
3.8 compass card: Graduated dial of the compass which indicates the measured direction of the meridian.
39 latitude error: Error to which some gyro-compasses are subject 9 the magnitude and sign of which depend
upon the local latitude.
NOTE - Means are provided for correcting this error.
3.10 speed error: Error to which gyro-compasses are subject, the magnitude and sign of which depend upon the
speed, course and latitude of the ship.
NOTE - Means are provided for correcting this error.
3.11 lubber line: Index line situated on the body of a compass against which the compass heading is read.
3.12 master compass: Main compass unit which supplies the heading information to the repeaters and other
navigational aids.
3.13 Scorsby table: Test machine which independently oscillates a platform about three axes; it is used to
simulate the motion of a ship.
4 Construction
Gyro-compass units shall conform to the following requirements.
4.1 The equipment shall be capable of continuous operation under conditions of vibration, humidity, change of
temperature and variations of the power supply as specified in 6.10.1 to 6.105
carry bearing
4.2 For those ships are required to repeater compasses, the con struction of shall be as
follows.
a) The bearing repeater compass shall be designed to be fitted with an azimuth reading device.
b) A gimbal mechanism shall be provided to enable the bearing repeater compass card to be held horizontally
against the ship’s motion
c) Any bearing repeater compass intended for use on an open deck shall be waterproof.
4.3 The compass card shall be graduated at equal intervals of 1 O or fraction thereof.
The graduation error shall be less than + 0,2”.
A numerical indication shall be provided at least at every IO”, starting from OOOO clockwise through 360°.
4.4 Fully adequate illumination shall be provided to enable the reading of all compass cards at all times. Facilities
for dimming shall be provided.
4.5 Both master compass and repeater compasses shall be provided with a lubber line to indicate the ship’s
heading.
4.5.1 The base or some other fixed extremity of the compass shall be marked or identified in such a way as to
facilitate the installation of the compass in a ship SO that the lubber line lies in a vertical fore-and-aft plane of the
ship. Where a gyro-compass has the facility of introducing a correction by moving the lubber line, the correction
during installation shall be set to zero.
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IS0 8728:1997(E)
If such marks or identifications are not in the same vertical plane as the uncorrected lubber line, then the horizontal
angular relationship between them shall be clearly indicated.
4.6 Means shall be provided for correcting the errors induced by speed and latitude. Graphical or tabular means of
correction may be used.
4.7 Steps shall be taken to eliminate as far as is practical the causes of, and to suppress, electromagnetic
interference between the gyro-compass and other equipment on board.
4.8 Mechanical noise from all units shall be so limited as to ensure the hearing of sounds on which the safety of
the ship may depend.
4.9 The equipment shall be so constructed that it is readily accessible for maintenance purposes.
4.10 An automatic alarm shall be provided to indicate a power failure in the gyro-compass.
4.11 Means shall be incorporated for the protection of the equipment from excessive currents and voltages,
transients and accidental reversal of power supply polarity.
4.12 The gyro-compass shall be designed to enable heading information to be provided to other navigational aids.
5 Performance requirements
5.1 Accuracy in latitudes up to 60”
51.1 Settling time
When switched on in accordance with the manufacturer’s instructions, the compass shall settle within 6 h.
5.1.2 Settle point error
5.1.2.1 The settle point error as defined in 3.5 at any heading shall not exceed * 0,75” x secant latitude, and the
RMS value of the differences between individual heading indications and the mean value shall be less than 0,25” x
secant latitude.
5.1.2.2 The repeatability of settle point error from one run-up to another shall be within 0,25O x secant latitude.
5.1.3 Settling time under operational conditions
When switched on in accordance with the manufacturer’s instructions, the compass shall settle within 6 h when
rolling and pitching with simple harmonic motion of any period between 6 s and 15 s, a maximum angle of 5”, and a
maximum horizontal acceleration of 0,22 m/s?
5.1.4 Settle point error under general conditions
The repeatability of the settle point error of the master compass shall be within + lo x secant latitude under the
general conditions and including variations in magnetic fields likely to be experienced in the ship in which it is
installed.
5.1.5 Residual error in correction
The residual steady state error, after correction for speed and course influences at a speed of 20 knl), shall not
exceed + 0,25” x secant latitude.
5.1.6 Effect of alteration of speed
The error due to a rapid alteration of speed of 20 kn shall not exceed + 2O.
1) knots
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IS0 8728: 1997(E)
5.1.7 Effect of alteration of course
The error due to a rapid alteration of course of 180” at a speed of 20 kn shall not exceed + 3”.
5.1.8 Accuracy on a Scorsby table
The transient and steady state errors due to rolling, pitching, and yawing, with simple harmonic motions of any
period between 6 s and 15 s, maximum angles of 20”, IO” and 5” respectively, and a maximum horizontal
acceleration not exceeding 1 m/s? shall not exceed + 1 O x secant latitude.
5.1.9 Synchronization between the master compass and repeaters
Once the repeaters have been synchronized with the master, the maximum divergence in reading between the
master compass and repeaters under all operational conditions shall not exceed + 0,s”; for the purposes of this
requirement, the latitude and speed correction shall be assumed equal to zero.
5.2 Other requirements
Gyro-compasses shall be in accordance with the requirements of IEC 945:1994, clause 3.
6 Type tests
6.1 Construction
The construction of the gyro-compass shall conform to the requirements specified in clause 4.
6.2 Settling time test
The master compass shall be securely positioned on a nominally level and stationary base. It shall be energized
from nominal value power supplies and started in accordance with the manufacturer’s instructions from an initial
heading error (high) of 30’ or more.
The settling time (see 3.3) shall meet the requirements of 5.1 .I.
6.3 Settle point error test
When the master compass has settled as defined in 3.3, the settle point error (see 3.5) shall conform to the
requirements specified in 5.1.2.1.
6.4 Settle point heading repeatability test
The master compass shall be started in accordance with the manufacturer’s instructions from an initial heading error
(high) of 30” or more and shall be allowed to settle.
The settle point heading shall be determined as specified in 3.4. The master compass shall then be switched off for
a period of not less than 12 h and not more than 7 days and then started again from an initial heading error (low) of
30° or more and the settle point heading measured again. The master compass shall then be switched off for a
period of not less than 12 h and not more than 7 days and then started again from an initial heading error (high) of
30’ or more and the settle point heading determined. The three values of settle point heading so obtained shall be
recorded and the difference between any two shall not exceed 0,25” x secant latitude.
NOTE - If this test follows the test described in 6.3, then the “settle” obtained from that test may be used as the first value
required by this repeatability test provided that the second “settle” follows a switch off period of not less than 12 h and not more
than 7 days.
@ IS0 IS0 8728: 1997(E)
Settling time on a Scorsby table
6.5
The master compass shall be mounted on a Scorsby table with the master compass fore-and-aft line nominally
parallel with one axis of the table which shall be designated the roll axis.
The other nominally horizontal axis at right angles to the first shall be designated the pitch axis.
The compass shall then be switched on in accordance with the manufacturer’s instructions with the following
nominal simple harmonic table motions:
- roll axis: Peak amplitude 5O + lo, period 15 s + 1 s;
- pitch axis: Peak amplitude 5O +, 1 O, period 6 s + 1 s.
The settling time measured between switch-on and compass settle as defined in 3.3 shall conform to the
requirements specified in 5.1.3.
Compass readings to determine the settle condition may be taken with the Scorsby stationary and nominally
NOTE - table
level, and with a minimum delay before resuming the specified table motion.
6.6 Scorsby test
The master compass shall be settled on the Scorsby table with the table stationary, nominally level and its roll axis
aligned North-South within +, 1 O.
The compass lubber line shall be
...
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