ISO 16328:2026
(Main)Ships and marine technology — Gyro-compasses for high-speed craft
- Abstract
This document specifies the minimum requirements, construction, performance and type testing for gyro-compasses for high-speed craft, which are required to comply with the International Convention for the Safety of Life at Sea (SOLAS) 1974 (as amended), Chapter X and the performance standards adopted by the IMO Resolution A.821(19).
- Status
- Published
- Publication Date
- 01-Nov-2026
- Technical Committee
- ISO/TC 8/SC 6 - Navigation and ship operations
- Drafting Committee
- ISO/TC 8/SC 6 - Navigation and ship operations
- Current Stage
- 6060 - International Standard published
- Start Date
- 02-Nov-2026
- Completion Date
- 02-Nov-2026
ISO 16328:2026 is an ISO standard for gyro-compasses for high-speed craft. It specifies the minimum requirements, construction, performance and type testing for equipment used on craft that must comply with SOLAS 1974, Chapter X, and the performance standards in IMO Resolution A.821(19). In practice, it tells manufacturers, installers, surveyors and test labs what a compliant gyro-compass system must do and how to verify it.
What does ISO 16328:2026 specify?
ISO 16328:2026 covers the complete gyro-compass equipment for high-speed craft, including construction features, performance limits, interface behavior, alert handling and type tests. The standard is written for systems that determine the craft’s true heading and distribute that heading to repeaters and other navigational equipment.
The document is organized into clauses 1 to 9, followed by four annexes. Clause 5 covers construction requirements, Clause 6 covers performance requirements, Clause 7 covers type tests, Clause 8 covers marking and identification, and Clause 9 covers information for operation and maintenance.
| Annex | What it covers |
|---|---|
| Annex A | Requirements for ship surveyors for the installation of gyro-compasses and repeater compasses on board crafts |
| Annex B | Vehicle test, used when there is an indication of a physical problem |
| Annex C | Alerts definition for gyro-compasses, including standard alert identifiers |
| Annex D | IEC 61162 series interfaces for VDR and other external equipment |
What are the key requirements of ISO 16328:2026?
ISO 16328:2026 requires a gyro-compass system that can support steering, bearing taking, heading output and alerting on high-speed craft. The most important practical points are the heading accuracy, the repeatability under motion, the interface to other ship systems, and the way faults are signaled.
Construction and installation
Clause 5 requires the gyro-compass equipment to include a compass card or analogue repeater for steering and equipment for taking visual bearings. It also requires continuous operation under vibration, humidity, temperature change and power-supply variation, so the system must remain usable in real ship conditions.
Clause 5 also sets construction details for bearing repeater compasses, graduation, illumination, lubber line arrangement and installation. The compass card must be graduated at 1° or finer intervals, with numerical indication at least every 10°, and any digital display must show the course in three digits with optional tenths. In practice, this affects what the bridge crew can read and how precisely the heading can be displayed and aligned.
Heading accuracy and settling behavior
Clause 6.1 sets the main performance limits up to 70° latitude. The compass must settle within 6 h after switch-on, and its settle point error and repeatability are limited as a function of secant latitude. That means the permitted error grows with latitude, so the test results must be interpreted at the operating latitude of the craft.
Clause 6.1.3 to 6.1.5 extends these limits to rolling, pitching, rapid speed changes and course changes. The standard also allows simulation and, where needed, a vehicle test if there is evidence of a physical problem. For users, this means the compass must stay within limits not only when stationary but also during the motions and manoeuvres typical of high-speed craft.
Master compass and repeater synchronization
Clause 6.1.6 requires the master compass and repeaters to stay closely aligned after synchronization. The maximum divergence in reading is limited to ± 0,5°, and the follow-up rate of the transmission system must be at least 20°/s. In practice, this is what keeps a repeater usable during turns and prevents the bridge from seeing inconsistent headings.
Interfaces and external equipment
Clause 6.3 requires interface facilities that meet IEC 61162-1, IEC 61162-2 or IEC 61162-450. The heading output must be updated once every 20 ms, and the THS sentence is required for heading information. This matters when the gyro-compass feeds radar, ARPA, radio direction-finder, VDR, speed correction functions or other ship systems.
Alert management and fault signaling
Clause 6.4 requires alert signaling for external power failure and internal system malfunction that invalidates heading information. If display equipment is used for alert management, it must comply with IMO Resolution MSC.191(79), as amended, and IEC 62288. The alert handling itself must follow IMO Resolution MSC.302(87), IEC 62923-1 and IEC 62923-2, with the gyro-compass alerts defined in Annex C.
Type testing
Clause 7 turns the performance requirements into test methods. It includes settling time, settle-point-error, repeatability, Scorsby table motion tests, repeater accuracy, speed error correction, environmental tests, interface tests and alert-management tests. For procurement and certification, this clause shows how compliance is demonstrated rather than just stated.
Marking and user information
Clause 8 requires each unit to show the manufacturer identification, the tested model identification and serial number, plus the minimum safe distance from magnetic compasses. Clause 9 requires information that lets crew members operate and maintain the equipment efficiently, including a qualitative description of heading errors caused by speed, acceleration, course changes and sea state.
What terms does ISO 16328:2026 define?
ISO 16328:2026 defines the core navigation terms used throughout the standard.
- Gyro-compass - the complete equipment, including the heading sensor and heading transmission system, not just the sensing element.
- True heading - the horizontal angle from true north to the craft’s fore-and-aft datum line.
- Settled - the condition reached when three readings taken 30 min apart stay within 0,7° while the compass is level and stationary.
- Settle point heading - the mean of ten readings taken at 20 min intervals after the compass has settled.
- Settle point error - the difference between the settle point heading and true heading.
- Repeater compass - a device that reproduces the master compass card at a remote location.
- Master compass - the main compass unit that supplies heading information to repeaters and other navigational aids.
- Bridge alert management (BAM) - the overall concept for managing and presenting alerts on the bridge.
Who uses ISO 16328:2026?
ISO 16328:2026 is used by gyro-compass manufacturers, system integrators, shipbuilders, marine surveyors, test laboratories and operators of high-speed craft. Manufacturers use it to design the equipment and set up type testing. Installers and surveyors use it to check alignment, safe mounting distance and repeater placement. Buyers and technical managers use it to confirm that the supplied gyro-compass can interface with bridge equipment, support alert management and meet the required test regime.
What changed in ISO 16328:2026 from the previous edition?
ISO 16328:2026 is the third edition and it cancels and replaces ISO 16328:2014. The stated changes are:
- Clause 4 on abbreviated terms was added.
- Clause 6.4 added requirements related to bridge alert management.
- Clause 7.1 added a requirement for display equipment.
- Clause 7.12 added a test method for bridge alert management requirements.
- Annex C was replaced with a new annex on alerts definition, including alert identifiers.
- Annex D was added with an IEC 61162 series interfaces overview.
- The normative references and bibliography were updated.
Which standards are used with ISO 16328:2026?
ISO 16328:2026 cites these documents in Clause 2 and uses them to define tests, interfaces and alert behavior:
- IEC 60945 - general requirements, test methods and required test results for maritime navigation and radiocommunication equipment.
- IEC 61162-1 - digital interface for single talker and multiple listeners, including the THS sentence and other message formats.
- IEC 61162-2 - high-speed transmission version of the digital interface.
- IEC 61162-450 - Ethernet-based multiple-talker, multiple-listener interconnection.
- IEC 62288 - presentation of navigation-related information on shipborne displays.
- IEC 62923-1 - bridge alert management operational and performance requirements and test methods.
- IEC 62923-2 - alert and cluster identifiers and additional bridge alert features.
- IMO Resolution A.424 (XI) - performance standards for gyro-compasses in the lower speed range noted by the standard.
- IMO Resolution MSC.302(87) - performance standards for bridge alert management.
- IMO Resolution MSC.191(79) - presentation standards for navigation-related information on shipborne displays.
- IMO Resolution A.694(17) - general requirements for shipborne radio equipment and electronic navigational aids.
What does the ISO 16328:2026 document contain?
ISO 16328:2026 contains specific test setups and verification methods for motion, power, temperature, humidity, vibration and interface behavior. It includes Scorsby table procedures, repeatability checks, speed-error correction checks and environmental exposure tests for the gyro-compass and its repeaters.
It also contains a figure for the logical interface structure and tables for transmitted and received IEC 61162 series sentences. Annex C gives the required alert identifiers and classifications, while Annex D lists the data exchanges used with VDR and other external equipment.
The document also provides a vehicle test case in Annex B for situations where a physical problem is suspected, and surveyor guidance in Annex A for installation alignment on board crafts.
Relations
- Effective Date
- 06-Jun-2022
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Frequently Asked Questions
ISO 16328:2026 is a standard published by the International Organization for Standardization (ISO). Its full title is "Ships and marine technology — Gyro-compasses for high-speed craft". This standard covers: This document specifies the minimum requirements, construction, performance and type testing for gyro-compasses for high-speed craft, which are required to comply with the International Convention for the Safety of Life at Sea (SOLAS) 1974 (as amended), Chapter X and the performance standards adopted by the IMO Resolution A.821(19).
This document specifies the minimum requirements, construction, performance and type testing for gyro-compasses for high-speed craft, which are required to comply with the International Convention for the Safety of Life at Sea (SOLAS) 1974 (as amended), Chapter X and the performance standards adopted by the IMO Resolution A.821(19).
ISO 16328:2026 is classified under the following ICS (International Classification for Standards) categories: 47.020.70 - Navigation and control equipment. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 16328:2026 has the following relationships with other standards: It is inter standard links to ISO 16328:2014. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO 16328:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
International
Standard
ISO 16328
Third edition
Ships and marine technology —
2026-11
Gyro-compasses for high-speed
craft
Navires et technologie maritime — Compas gyroscopiques pour
navires à grande vitesse
Reference number
© ISO 2026
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ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
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 .5
5.7 Fore and aft mark .5
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 .6
6.1.3 Settling time under operational conditions .6
6.1.4 Settle point error under operational conditions .6
6.1.5 Performance under operational conditions .6
6.1.6 Synchronization between the master compass and repeaters .6
6.2 Other requirements .7
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) .8
6.4.3 Malfunction of the gyro-compass system (“system fault” alert) .8
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 .9
7.6 Scorsby test.9
7.7 Intercardinal motion test .9
7.8 Repeater accuracy test .10
7.9 Speed error correction test .10
7.10 General requirement test .10
7.10.1 General .10
7.10.2 Voltage variation test .11
7.10.3 Frequency variation test .11
7.10.4 Vibration test .11
7.10.5 Temperature test . . 12
7.10.6 Damp heat test . . 12
7.10.7 Other tests . 12
7.11 Interface test . 13
iii
7.12 Alert management test . 13
7.12.1 Basic test for alert management . 13
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 . 14
Annex A (normative) Requirements for ship surveyors for the installation of gyro-compasses
and repeater compasses on board crafts .15
Annex B (informative) Vehicle test . 16
Annex C (normative) Alerts definition for gyro-compasses . 17
Annex D (normative) IEC 61162 series interfaces for VDR and other external equipment .18
Bibliography .20
iv
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
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
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, a test method for requirements related to bridge alert management has been added;
— Annex C has been replaced with a new Annex on alerts definition, including alert identifiers;
— in Annex D, an IEC 61162 series 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.
v
Introduction
[4]
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.
vi
International Standard ISO 16328:2026(en)
Ships and marine technology — Gyro-compasses for high-
speed craft
1 Scope
This document specifies the minimum requirements, construction, performance and type testing for gyro-
compasses for high-speed craft, which are required to comply with the International Convention for the
[4]
Safety of Life at Sea (SOLAS) 1974 (as amended), Chapter X and the performance standards adopted by the
[4]
IMO Resolution A.821(19).
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.
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 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
3 Terms and definitions
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
[4]
[SOURCE: IMO Resolution A.821(19), 2.1, modified — “complete equipment comprising all essential
elements of 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 (3.1) 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.
[4]
[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.
[4]
[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)
[4]
[SOURCE: IMO Resolution A.821(19), 2.5]
3.6
error
difference between the observed value and the settle point heading (3.4)
Note 1 to entry: In this document, if the true heading (3.2) is unknown —other than in the case of a settle point error
(3.5) (the difference from the true heading) — quantitative heading error is evaluated using the settle point heading
(3.4) instead of the true heading defined here.
[4]
[SOURCE: IMO Resolution A.821(19), 2.6, modified — note 1 to entry has been added.]
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: IEC 62923-1:2018, 3.18]
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
BAM bridge alert management
CAM central alert management
EUT equipment under test
GC gyro-compass
GNSS global navigation satellite system
SDME speed and distance measuring equipment
VDR voyage data recorder
5 Construction requirements
5.1 Gyro-compass equipment
[4]
In accordance with IMO Resolution A.821(19), Section 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.
5.2 Continuous operation
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.
5.3 Bearing repeater compass
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.
5.4 Graduation and digital display
[4]
In accordance with IMO Resolution A.821(19), Section 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.
5.5 Illumination
Adequate illumination shall be provided to enable the reading of all compass cards at all times. Facilities for
dimming shall be provided.
5.6 Lubber line
Devices using a compass card shall be provided with a lubber line to indicate the craft's heading.
5.7 Fore and aft mark
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.
5.8 Installation
[4]
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.
5.9 Speed error correction
4]
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.
5.10 Heading information
[4]
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.
5.11 Status signal
[4]
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.
5.12 Power supply
[4]
In accordance with IMO Resolution A.821(19), Section 5, the gyro-compass shall be provided with or
connected to an uninterruptable power supply.
6 Performance requirements
6.1 Accuracy in latitudes up to 70°
6.1.1 Settling time
[4]
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.
6.1.2 Settle point error
[4]
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.
6.1.3 Settling time under operational conditions
[4]
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/s .
6.1.4 Settle point error under operational conditions
[4]
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 t
...