ISO/DIS 16328:2025(en)

ISO/TC 8/SC 6

Secretariat: JISC

Date: 2025-06-05

Ships and marine technology — Gyro-compasses for high-speed craft

© ISO 2025

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Contents

Foreword v

Introduction vi

1 Scope 1

2 Normative references 1

3 Terms and definitions 2

4 Abbreviated terms 3

5 Construction requirements 4

5.1 Gyro-compass equipment 4

5.2 Continuous operation 4

5.3 Bearing repeater compass 4

5.4 Graduation and digital display 4

5.5 Illumination 4

5.6 Lubber line 4

5.7 Fore and aft mark 4

5.8 Installation 5

5.9 Speed error correction 5

5.10 Heading information 5

5.11 Status signal 5

5.12 Power supply 5

6 Performance requirements 5

6.1 Accuracy in latitudes up to 70° 5

6.1.1 Settling time 5

6.1.2 Settle point error 5

6.1.3 Settling time under operational conditions 5

6.1.4 Settle point error under operational conditions 5

6.1.5 Performance under operational conditions 6

6.1.6 Synchronization between the master compass and repeaters 6

6.2 Other requirements 6

6.3 Interface 7

6.4 Alert management 7

6.4.1 General 7

6.4.2 Power failure in the gyro-compass (“Power fail” alert) 7

6.4.3 Malfunction of the gyro-compass system (“system fault” alert) 7

7 Type tests 8

7.1 General 8

7.2 Settling time test 8

7.3 Settle-point-error test 8

7.4 Settle-point-heading repeatability test 8

7.5 Settling time on a Scorsby table 8

7.6 Scorsby test 9

7.7 Intercardinal motion test 9

7.8 Repeater accuracy test 9

7.9 Speed error correction test 10

7.10 General requirement test 10

7.10.1 General Information 10

7.10.2 Voltage variation test 10

7.10.3 Frequency variation test 10

7.10.4 Vibration test 10

7.10.5 Temperature test 12

7.10.6 Damp heat test 12

7.10.7 Other tests 12

7.11 Interface test 12

7.12 Alert management test 12

7.12.1 Basic test for alert management 12

7.12.2 "Power fail” alert or output of a status signal on the EUT power 13

7.12.3 "system fault” alert 13

8 Marking and identification 13

9 Information 13

Annex A (normative) Requirements for ship surveyors for the installation of gyro- compasses and repeater compasses on board crafts 14

Annex B (informative) Vehicle test 15

Annex C (normative) Alerts definition for gyro-compasses 16

Annex D (normative) IEC 61162 interfaces for VDR and other external equipment 17

Bibliography 19

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.

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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee SC 6, Navigation and ship operations.

This third edition cancels and replaces the second edition (ISO 16328:2014), which has been technically revised.

The main changes are as follows:

— Clause 4, (abbreviated terms) has been added;

— in 6.4, requirements related to bridge alert management have been added;

— in 7.1, a requirement for display equipment has been added;

— in 7.12, test method for requirements related to bridge alert management has been added;

— in Annex C, the equivalent requirements in this International Standard and IMO Resolutions have been deleted and the alerts with a standard alert identifier have been defined.

— in Annex D, IEC 61162 interfaces overview has been added.

— the normative references and bibliography have been updated.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

This document is aligned with IMO Resolution A.821(19) on performance standards for gyro-compasses for high speed craft.

Any text in this document which is a citation from the IMO Resolution A.821(19), appears in italics. Within these citations, any changes to the original wording of the IMO Resolution A.821(19) are written in upright font.

In this document, the following verbal forms are used:

— “shall” indicates a requirement;

— “should” indicates a recommendation;

— “may” indicates a permission;

— “can” indicates a possibility or a capability.

Ships and marine technology — Gyro-compasses for high-speed craft

This document specifies the construction, performance, and type testing for gyro-compass for high-speed craft which are required by the International Convention for the Safety of Life at Sea (SOLAS) 1974 (as amended), chapter X.

This document specifies the minimum requirements, the construction, performance, and type testing for gyro-compasses for high-speed craft, which required to comply with the performance standards adopted by the IMO Resolution A.821(19).

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.

IEC 60945, Maritime navigation and radiocommunication equipment and systems — General requirements — Methods of testing and required test results

IEC 61162‑1, Marine navigation and radiocommunication equipment and systems — Digital interfaces — Part 1: Single talker and multiple listeners

IEC 61162‑2, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part 2: Single talker and multiple listeners, high-speed transmission

IEC 61162‑450, Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 450: Multiple talkers and multiple listeners - Ethernet interconnection

IEC 62288, Maritime navigation and radiocommunication equipment and systems — Presentation of navigation-related information on shipborne navigational displays — General requirements, methods of testing and required test results

IEC 62923‑1, Maritime navigation and radiocommunication equipment and systems — Bridge alert management — Part 1: Operational and performance requirements, methods of testing and required test results

IEC 62923‑2, Maritime navigation and radiocommunication equipment and systems — Bridge alert management — Part 2: Alert and cluster identifiers and other additional features

IMO Resolution A.424 (XI), Performance standards for gyro-compasses

IMO Resolution MSC.302(87), performance standards for bridge alert management

IMO Resolution MSC.191(79), Performance standards for the presentation of navigation-related information on shipborne navigational displays

IMO Resolution MSC.466(101), Amendments to the performance standards for the presentation of navigation-related information on shipborne navigational displays (Resolution MSC.191(79))

IMO Resolution A.694(17), General requirements for shipborne radio equipment forming part of the global maritime distress and safety system (GMDSS) and for electronic navigational aids

IMO Resolution A.1021(26), Code on alerts and indicators, 2009

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

gyro-compass

complete equipment comprising all essential elements of the complete design, including both the gyro-compass as heading sensor and the associated heading transmission system

[SOURCE: IMO Resolution A.821(19), 2.1, modified — “complete equipment ……..the complete design” has been added]

3.2

true heading

horizontal angle between the vertical plane passing through the true meridian and the vertical plane passing through the craft's fore-and-aft datum line

Note 1 to entry: The true heading is measured from true north (000°) clockwise through 360°.

Note 2 to entry: When the gyro-compass equipment is tested on the test stand, this “true heading” is regarded as the true heading 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.

[SOURCE: IMO Resolution A.821(19), 2.2, modified — notes 1 and 2 to entry have been added.]

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

Note 1 to entry: The settling time is the elapsed time between the time of switch-on at the initial heading error and the third recording of the settle.

[SOURCE: IMO Resolution A.821(19), 2.3, modified — note 1 to entry has been added.]

3.4

settle point heading

mean value of ten readings taken at 20 min intervals after the compass has settled (3.3)

[SOURCE: IMO Resolution A. 821(19), 2.4]

3.5

settle point error

difference between the settle point heading (3.4) and the true heading (3.2)

[SOURCE: IMO Resolution A.821(19), 2.5]

3.6

error

difference between the observed value and the settle point heading (3.4)

[SOURCE: IMO Resolution A.821(19), 2.6]

3.7

repeater compass

device that reproduces the master compass card at a remote location

3.8

bearing repeater compass

device that reproduces the master compass card for the purpose of taking bearings

3.9

compass card

graduated dial of the compass which indicates the measured direction of the meridian

3.10

latitude error

error (3.6) to which some gyro-compasses (3.1) are subject, the magnitude and sign of which depend upon the local latitude

Note 1 to entry: Means are provided for correcting this error.

3.11

speed error

error (3.6) to which gyro-compasses (3.1) are subject, the magnitude and sign of which depend upon the speed, course, and latitude of the craft

Note 1 to entry: Means are provided for correcting this error.

3.12

lubber line

index line situated on the body of gyro-compass or repeater compass against which the compass card is read

3.13

master compass

main compass unit which supplies the heading information to the repeaters and other navigational aids

3.14

Scorsby table

test machine which enables a platform to oscillate independently about three axes

Note 1 to entry: it is used to simulate the motion of a craft.

3.15

bridge alert management (BAM)

overall concept for management, handling and harmonized presentation of alerts on the bridge

[SOURCE: IMO Resolution MSC.302(87), Appendix 1]

3.16

central alert management system (CAM system)

combined functionality of the central alert management and the central alert management human machine interface

[SOURCE: IMO Resolution MSC.302(87), Appendix 1]

For the purposes of this document, the following abbreviated terms apply.

In accordance with IMO Resolution A.821(19), 3, gyro-compass equipment shall include the provision of a compass card or analogue repeater for steering purposes and equipment for the purpose of taking visual bearing.

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 7.10.

For crafts which are required to carry a bearing repeater compass, the construction of these 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 craft's motion.

c) Any bearing repeater compass intended for use on an open deck shall be waterproof.

In accordance with IMO Resolution A.821(19), 3, the compass card shall be graduated at equal intervals of 1° or a fraction thereof.

The graduation error shall be less than ±0,2°.

A numerical indication shall be provided at least at every 10°, starting from 000° clockwise through 360°.

A digital display may be provided. When a digital display is provided, the course shall be displayed as three digits plus, optionally, a fourth digit indicating tenths of a degree. When a gyro-compass with digital display is used, it shall incorporate a turning direction indicator.

Adequate illumination shall be provided to enable the reading of all compass cards at all times. Facilities for dimming shall be provided.

Devices using a compass card shall be provided with a lubber line to indicate the craft's heading.

If technically necessary, the compass shall be marked in a way to facilitate installation so that the lubber line lies in a vertical fore and aft plane of the craft or parallel. 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.

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 in the manufacturer’s installation instruction.

In accordance with IMO Resolution A.821(19), 6.1, the master compass and any repeaters used for taking visual bearings shall be installed or adjusted in a craft with their fore and aft datum lines parallel to the craft’s fore and aft datum line to within ±0,5°. The lubber line shall be in the same vertical plane passing through the centre of the card of the compass and shall be aligned accurately in the fore and aft direction.

Requirements for ship surveyors for the installation of gyro-compasses and repeater compasses on board crafts shall be in accordance with Annex A.

In accordance with IMO Resolution A.821(19), 6.2, means shall be provided for correcting the errors induced by speed and latitude. An approved accurate speed source shall be used for automatic speed error corrections.

In accordance with IMO Resolution A.821(19), 6.5, the gyro-compass shall be designed to enable heading information to be provided to other navigational aids such as radar, ARPA, radio direction-finder, and heading control system. The accuracy of the other navigational aids shall not be degraded, and shall continue to comply with the standards specified for such aids.

In accordance with IMO Resolution A.821(19), 6.3, a status signal shall be provided to indicate that the gyro-compass is ready for use.

In accordance with IMO Resolution A.821(19), 5, the gyro-compass shall be provided with or connected to an uninterruptable power supply.

In accordance with IMO Resolution A.821(19), 4.1.1, when switched on in accordance with the manufacturer's instructions, the compass shall settle within 6 h.

In accordance with IMO Resolution A.821(19), 4.1.2, the settle point error at any heading shall not exceed ±0,75° × secant latitude, and the RMS value of the differences between individual heading indications and the mean value shall be less than 0,25° × secant latitude. In accordance with IMO Resolution A.821(19), 4.1.3, the repeatability of settle point error from one run-up to another shall be within 0,25° × secant latitude.

In accordance with IMO Resolution A.821(19), 4.2.1, 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/s².

In accordance with IMO Resolution A.821(19), 4.2.2, the repeatability of the settle point error of the master compass shall be within ±1° × secant latitude, including variations in magnetic fields likely to be experienced in the craft in which it is installed.

In accordance with IMO Resolution A.821(19), 4.2.3, in craft operating within a latitude band of 10°:

The requirements of 6.1.5 a) shall be checked by means of simulation. The requirements of 6.1.5 b) and 6.1.5 c) shall also be checked by means of simulation and by a vehicle test (sea or land) if necessary. The vehicle test shall only be performed if there is an indication of a physical problem or problems (see Annex B for information). The vehicle test shall be performed under realistic traffic conditions and the maximum acceleration in this test shall be in a band of 1 m/s² to 2 m/s².

a) In accordance with IMO Resolution A.821(19), 4.2.3.1, the residual steady-state error, after correction for speed and course influences at a speed of 70 kn^[1], shall not exceed ±0,25° × secant latitude.

b) In accordance with IMO Resolution A.821(19), 4.2.3.2, the maximum error due to a rapid alteration of speed of 70 kn¹ shall be kept to a minimum, and shall not exceed ±2°. The horizontal acceleration shall not exceed 2,0 m/s².

c) In accordance with IMO Resolution A.821(19), 4.2.3.3, the error due to a rapid alteration of course of 180° up to maximum rate of turn of 20°/s in any azimuth direction up to a speed of 70 kn¹ shall not exceed ±3°. The horizontal acceleration shall not exceed 2,0 m/s².

d) In accordance with IMO Resolution A.821(19), 4.2.3.4, 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°, 10°, and 5° respectively, and a maximum horizontal acceleration not exceeding 1 m/s², and at any course especially at 45°, 90°, and 315° shall not exceed ±1° × secant latitude.

In accordance with IMO Resolution A.821(19), 4.2.5, once the repeaters have been synchronized with the master, the maximum divergence in reading between the master compass and repeater under all operational conditions shall not exceed ±0,5°. For the purposes of this requirement, the latitude and speed correction shall be assumed equal to zero.

In accordance with IMO Resolution A.821(19), 4.2.6, the follow-up rate of the transmission system shall be at least 20°/s.

In accordance with IMO Resolution A.821(19), 1.1, the gyro-compass shall determine the direction of the head of the high-speed crafts (HSC) in relation to geographic (true) north.

In accordance with IMO Resolution A.821(19), 1.2, in addition to the general requirements contained in IMO Resolution A.694 (17), the gyro-compass equipment installed in craft operating under the following conditions:

1 speed exceeding 30 kn¹ and up to 70 kn¹;

2 maximum rate of turn 20°/s;

3 normal range of operation between 70° N and 70° S shall, as required by chapter 13 of the HSC Code, comply with the minimum performance requirements specified in these standards.

In accordance with IMO Resolution A.821(19), 1.3, the gyro-compass, within a speed range of up to 30 kn¹, shall comply with the requirements of IMO Resolution A.424 (XI), and within a speed range of 30 kn¹ to 70 kn¹ shall comply with the requirements of this document.

Other requirements shall be in accordance with the relevant clauses in IEC 60945.

NOTE 1 See Annex D.

In accordance with IMO Resolution A.821(19), 7, the gyro-compasses equipment shall provide with an output of heading information with an accuracy as defined in 6.1.6 when interfaced by other equipment.

The compass shall provide interface facilities which meet IEC 61162-1, IEC 61162-2 or IEC 61162-450.

The gyro-compass equipment shall provide an appropriate data source and at least one output of heading information. The heading output shall be updated at a rate of once every 20 ms. The THS sentence detailed in IEC 61162-1 shall be provided for heading information.

NOTE 2 THS refers a sentence formatter which is described in IEC 61162-1.

The Sentences from IEC 61162-1 shall be in accordance with Annex D.

In accordance with IMO Resolution A.821(19), 6.4, an alert signal shall be provided to indicate that the gyro-compass has suffered an external power supply failure or an internal system functional failure (i.e. malfunction) which would invalidate the heading information.

If the gyro-compass uses display equipment for alert management, it shall comply with IMO Resolution MSC.191(79), as amended by IMO Resolution MSC.466(101), and with IEC 62288

The general presentation, handling and communication for alerts shall comply with the requirements stated in IMO Resolution MSC.302(87), IEC 62923-1, Module A and Module C, and IEC 62923-2, as a minimum.

The alerts with a standard alert identifier for gyro-compasses are specified in Table C.1.

NOTE 1 Alert titles and alert description texts used in Table C.1 and in the body text of this document are not mandatory alert titles and alert description texts, but are regarded as guidance. Alert titles and alert description texts used in the body text of this document are therefore indicated between double quotation marks (“ “).

The manufacturer of the gyro-compass shall declare the EUT function type for the bridge alert management (BAM) compliance test.

NOTE 2 According to the EUT function type, the relevant test set-up and test items are specified in BAM test standards. Refer to IEC 62923-1: EUT function types, Test methods, Module A and Module C.

In the case of power failure of the gyro-compass, a status signal (e.g. by normally closed contact) shall be provided to enable external equipment to raise the appropriate alert.

If the gyro-compass has another power supply for backup and can use display equipment during failure of one power supply, the “power fail” alert may be provided as specified in Table C.1.

When the self-diagnosis function of the gyro-compass detects the major malfunction of the system, the “system fault” alert with an appropriate priority or the minimum presentation indicating the cause of failure shall be activated as specified in Table C.1.

In the case of the malfunction whereby the gyro-compass system cannot operate at all, the status signal (e.g.by normally closed contact) shall be output as specified in 6.4.2 so that external equipment can raise a proper alert.

Unless otherwise stated in this document, confirm by inspection of documented evidence that the EUT complies with IEC 60945 (e.g. by using the tests specified in 7.10.7).

The construction of the EUT conforms to the requirements specified in Clause 5.

If the EUT uses display equipment, confirm by inspection of documented evidence that the EUT complies with IEC 62288.

The master compass of the EUT is securely positioned on a nominally level and stationary base. It is energized from nominal value power supplies and started in accordance with the manufacturer's instructions from an initial heading error (to east) of 30° or more.

Confirm by observation that the settling time meets the requirement specified in 6.1.1.

When the master compass of the EUT has settled, confirm by observation that the settle point error conforms to the requirements specified in 6.1.2.

The master compass of the EUT is started in accordance with the manufacturer's instructions from an initial heading error (to east) of 30° or more and is allowed to settle.

The settle point heading is determined. The master compass of the EUT is then switched off for a period of not less than 12 h and not more than 7 days. It is then started again from an initial heading error (to west) of 30° or more, and the settle point heading is measured again.

The master compass of the EUT is then switched off for a period of not less than 12 h and not more than 7 days. It is then started again from an initial heading error (to east) of 30° or more and the settle point heading is determined. The three values of the obtained settle point heading. are recorded. It is confirmed by observation that the difference between any two values does not exceed 0,25° × secant latitude.

NOTE If this test follows the text described in 7.3, then the “settle” obtained from that text can 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.

The master compass of the EUT is mounted on a Scorsby table with the master compass fore-and-aft line, nominally parallel with one axis of the table which is designated the roll axis.

The other nominally horizontal axis, (at right angles to the first axis) is designated the pitch axis.

The EUT is switched on in accordance with the manufacturer's instructions with the following nominal simple harmonic table motions:

— roll axis: peak amplitude 5° ± 1°, period 15 s ± 1 s;

— pitch axis: peak amplitude 5° ± 1°, period 6 s ± 1 s.

Confirm by observation that the settling time measured between switch-on and compass settle conforms to the requirements specified in 6.1.3.

NOTE Compass readings to determine the settle condition can be taken with the Scorsby table stationary and nominally level, and with a minimum delay before resuming the specified table motion.

The master compass of the EUT is settled on the Scorsby table with the table stationary, nominally level and its roll axis aligned north–south within ±1°.

The compass lubber line is aligned to within ±1° of the table roll axis. The following nominal simple harmonic motions are applied simultaneously to the three axes of the table for 25 min:

— roll axis: peak amplitude 25° ± 2°, period 6 s ± 1 s;

— pitch axis: peak amplitude 15° ± 2°, period 10 s ± 1 s;

— yaw axis: peak amplitude 5° ± 1°, period 15 s ± 1 s.

At the end of 25 min, the table motion is stopped, the table is returned to its original position and the compass heading is recorded without delay.

This test is repeated with the roll axis of the motion table aligned at 045° ± 1°, at 090° ± 1° and at 315° ± 1°. At each of these headings, the compass settle point is determined before commencing the table motion. Any change of heading indication by the compass between the settle point heading, immediately prior to the motion and the heading at the conclusion of the motion is recorded as an error due to motion.

In each of the four tests, confirm by observation that error due to the motion is less than ±1° × secant latitude.

Confirm by observation that any horizontal accelerations applied during this test does not exceed 1 m/s².

The master compass of the EUT is securely mounted on a device having the ability to move with nominal simple harmonic motion such that the component of motion in a horizontal plane has a peak acceleration of 1,0 m/s² ± 0,1 m/s². The direction of motion of the device in the horizontal plane is an intercardinal direction to within ±3°.

When so mounted, the compass is settled and the settle point heading is obtained with the device stationary and nominally levelled. The device then is submitted to the motion described previously, having a peak acceleration of 1,0 m/s² ± 0,1 m/s² with a periodic time of not less than 3 s, for a duration of 2 h. Any difference between the compass heading recorded during the motion and the settle point heading prior to the motion is considered as due to the motion. Confirm by observation that this difference does not exceed 1° × secant latitude.

Confirm by observation that the master compass heading recorded during the motion discounts any modulation at frequencies equal to or higher than the frequency of the applied motion.

This test only applies to the EUT which includes a repeater compass. The latitude and speed error correction are assumed to be equal to zero. The master compass of the EUT is settled on a level rotary table and the repeater is aligned with the master compass. The table and master compass are turned at a rate not greater than 20°/s, the table is stopped at every 30°, and the compass heading and the repeater heading recorded. The compass and repeater heading may be recorded simultaneously at every 30° as a minimum. This procedure is repeated in the reverse direction of rotation.

Confirm by observation that the maximum divergence in reading between the master compass and the repeater conforms to the requirements specified in 6.1.6.

NOTE The exact angle of the table when readings are taken is unimportant since the object of the test is to compare master and repeater heading indications.

If the repeater compass to be tested is intended for use on an open deck, it is tested at a temperature of −20 °C ± 3 °C and again at +60 °C ± 3 °C having been exposed to the test temperature for 2 h prior to the test. Any climatically controlled system designed as a part of the repeater installation may be switched on for this test.

With the master compass of the EUT mounted on a level and stationary base and the lubber line of the compass aligned to north, the master compass of the EUT is settled and the settled point heading is recorded.

A speed signal of 70 kn¹ is applied to the EUT and allowed to resettle.

Confirm by observation that the difference between the settle point heading obtained and the settle point heading initially recorded agrees with the value computed theoretically for the latitude of the test to within 0,25° × secant latitude.

If the latitude and speed correction is performed within the heading signal transmission system, the heading readings required for the purposes of this test are taken on a repeater driven by the transmission system on the output signal of the transmission system.

For these tests, the datum from which settle point variations are measured is the settle point heading obtained in the absence of the particular environmental condition to be applied. Where the EUT includes repeater compasses, at least one repeater compass of the EUT is energized and aligned with the master compass throughout the course of environmental tests. Each remaining repeater compass output is connected to a normal load, or to suitable impedance representing a normal load, supplied by the manufacturer.

The supply voltage is set to 10 % above the nominal value for 3 h, during which time the compass heading is recorded at 20 min  intervals. The supply voltage then is set to a value 10 % below nominal for 3 h, and the compass heading again recorded at 20 min  intervals.

Confirm by observation that none of the recorded headings departs from the original datum by more than 1° × secant latitude.

In case of an AC supply, the frequency is set to 5 % above the nominal value for 3 h, during which time the compass heading is recorded at 20 min  intervals. The supply frequency then is set to a value 5 % below nominal for 3 h and the compass heading again recorded at 20 min  intervals.

Confirm by observation that none of the recorded headings departs from the original datum by more than 1° × secant latitude.

Vibration test of master compass

In all of these tests, the direction of the master compass lubber line is +30° ± 1° to the meridian.

The master compass of the EUT is subjected to the vibration described below. Three separate tests are carried out, the direction of vibration being:

a) +30° ± 1° to the meridian and horizontal;

b) −60° ± 1° to the meridian and horizontal;

c) vertical.

In each case, the master compass of the EUT is settled initially and then the vibration is applied at the lowest frequency, holding the appropriate vibration amplitude for a period of 25 min . At the end of that period, the frequency and amplitude are changed to the next value shown in Table 1 and held for a further 25 min . This process continues until the entire frequency range has been covered.

Table 1 — Frequency and amplitude for vibration test of master compass

The indicated heading is recorded at the end of each period. Confirm by observation that any difference between these recorded heading and the datum settle point heading is not more than 1° × secant latitude during the test.

NOTE Provision can be made to reduce or nullify any adverse effect on the equipment performance caused by the presence of any electromagnetic field due to the vibration unit.

Vibration test of the EUT other than master compass

This equipment, complete with any shock absorbers which are part of it, is secured by its normal means of support to the vibration table. It then is connected in its normal electrical configuration to the master compass. The master compass is then switched on in accordance with the manufacturer's instructions and its settle point heading ascertained and recorded.

The equipment on the vibration table is then vibrated vertically at all frequencies between:

a) 5 Hz and 13,2 Hz with an amplitude of 1,0 mm;

b) 13,2 Hz and 40 Hz with a maximum acceleration of (0,7 × 9,8) m/s²;

taking at least 25 min to cover each frequency range.

This whole procedure is repeated when the equipment is vibrated in two mutually perpendicular directions in the horizontal plane.

Confirm by observation that there is no electrical or mechanical failure during any part of this series of tests.

The indicated heading is recorded at the end of each period.

Confirm by observation that any difference between these recorded heading and the datum settle point heading is not more than 1° × secant latitude during the test.

The EUT is placed in a chamber at normal room temperature, switched on and allowed to settle. The settle point heading is obtained and recorded. The temperature of the chamber is then raised to 45 °C ± 2 °C and maintained for a period of 3 h. At the end of this period, the compass heading indication again is recorded. The temperature of the chamber is then reduced to 0 °C ± 2 °C and maintained at this temperature for 3 h. At the end of this period, the compass heading indication is recorded once more.

Confirm by observation that neither of the recorded heading indications differs from the datum settle point heading by more than 1° × secant latitude.

NOTE When the temperature of the chamber is being changed, it does not alter by a rate which exceeds 45 °C/h.

The EUT is placed in a chamber at normal room temperature and humidity, switched on and allowed to settle. The settle point heading is obtained and recorded. Over a period of 3 h ± 0,5 h, the temperature and relative humidity of the chamber are then raised steadily to 40 °C ± 2 °C and 93 % ± 3 %, respectively. These conditions are maintained for a further period of 3 h ± 0,5 h.

Confirm by observation that the compass indication at the end of this test does not differ from the datum settle point heading by more than 1° × secant latitude.

a) Rain test

NOTE In the case of the rain test, only exposed equipment is tested.

b) Conducted interference test

c) Radiated interference test

d) Acoustic noise test

In the acoustic noise test, no measurement is made at the time of starting the EUT, and only equipment intended for installation in wheelhouse and bridge wings is tested.

NOTE See 6.3.

The interface facilities shall be subjected to the tests specified in IEC 61162-1, IEC 61162-2 or IEC 61162-450. Observe the heading output rate specified in IEC 61162-2 and ensure that it is updated at least once every 20 ms.

Confirm by observation that the interface as well as the repeaters meet the performance test specified in 7.8.

NOTE See 6.4.

Confirm by inspection of documented evidence that the EUT complies with IEC 62923-1, Module A and Module C, and with IEC 62923-2.

The sentences from IEC 61162-1 shall be in accordance with Annex D.

NOTE See 6.4.2 and Table C.1.

The method of testing and required test results of “power fail” alert or the output of a status signal on the EUT power is as follows:

a) Connect power to the power supply/supplies of the EUT.

b) Remove one power to the EUT.

In case the EUT blacks out due to power failure, confirm by observation that the EUT provides a status signal output as specified in 6.4.2.

Optionally, the EUT may activate a “power fail” alert of an appropriate priority by using backup power supply.

NOTE See 6.4.3 and Table C.1.

The method of testing and required test results of “system fault” alert is as follows:

a) Create a malfunction in the system that has a severe effect on the true heading.

b) Confirm by observation that the EUT activates a “system fault” alert of warning priority.

Each unit of a gyro-compass shall be marked with the following:

— identification of the manufacturer;

— equipment type number or model identification under which it was type tested;

— serial number of the unit.

Each unit of the equipment shall be marked with the minimum safe distance at which it may be mounted from a standard and a steering magnetic compass. The safe distance shall be measured in accordance with IEC 60945.

Information shall be provided to enable competent members of a craft's crew to operate and maintain the equipment efficiently.

In accordance with IMO Resolution A.821(19), 1.4, a qualitative description of the effects of gyro-compass errors due to high speed, accelerations, course changes, sea state, etc., and a qualitative description of corresponding errors in other navigational aids, shall be provided to the user.

1. 
   (normative)
   
   Requirements for ship surveyors for the installation of gyro-
   compasses and repeater compasses on board crafts

To ensure that the errors induced by the motions specified in 6.1.5 d) are not exceeded in practice, it is necessary to pay particular attention to the sitting of the master compass.

In accordance with IMO Resolution A.821(19), 6.1, where the master compass and/or any repeater compass are used for taking bearings, the horizontal angle between the vertical plane passing through the centre of the compass card, and including the lubber line, and the vertical plane passing through the craft's fore and aft datum line, shall be within ±0,5° when installed.

1. 
   (informative)
   
   Vehicle test

A vehicle test is only carried out if there is indication of a physical problem or problems, for example

a) mechanical boundaries,

b) data communications, and

c) stability under traffic conditions over a longer time interval.

A typical test may be performed under the following conditions.

The equipment is installed on a vehicle. The vehicle is accelerated slowly to a speed of approximately to 70 kn¹ or the maximum speed limited by the national traffic regulations on a road that is straight for a few kilometres. Before the turn is started, the vehicle slows down to a lower speed (10 kn¹ to 20 kn¹ or as necessary according to the vehicle, traffic, and environment). After a 180° turn, the vehicle is accelerated to a speed of approximately 70 kn¹ or the maximum speed limited by the national traffic regulations. The vehicle then stops at the end of the straight test road. The recorded course should be in a band of ±3° after the turn. Problems, for example, caused by data communication during the turn or other traffic situations, should be reduced to a minimum.

1. 
   (normative)
   
   Alerts definition for gyro-compasses

The alerts with a standard alert identifier for the gyro-compass (GC) are specified in Table C.1.

Table C.1 — Classification of gyro-compass required alerts

1. 
   (normative)
   
   IEC 61162 interfaces for VDR and other external equipment

The sentences specified in IEC 61162 for transmitting and receiving data for the gyro-compass are specified in Tables D.1 and D.2. The manufacturer shall specify which part of IEC 61162 supports each physical interface.

Figure D.1 shows the required logical interfaces. If more than one logical interface is implemented on a single physical interface, then all aspects of each logical interface, including alert communication, heartbeat, etc., shall be distinguishable from those of other logical interfaces implemented on the same physical interface.

Figure D.1 — Gyro-compass logical interfaces

NOTE The speed from a GNSS can be used for the correction of speed error.

Table D.1 — Sentences from IEC 61162-1 transmitted by the gyro-compass

Table D.2 — Sentences from IEC 61162-1 received by the gyro-compass

Bibliography

[1] ISO 8728, Ships and marine technology — Marine gyro-compasses

[2] IEC 61162‑3, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part 3: Serial data instrument network

[3] IMO Resolution A.821(19), Performance standards for gyro-compasses for high-speed craft

[4] International Convention for the Safety of Life at Sea (SOLAS) 1974 (amended)

1. The equivalence to SI units: “1 kn = 1,852 km/h” ↑