ISO 22090-2:2014

Overview

ISO 22090-2:2014 - Ships and marine technology: Transmitting heading devices (THDs) - Part 2: Geomagnetic principles - specifies construction, performance and testing for THDs that use only magnetic means. It defines how geomagnetic-type THDs provide true heading information required by Chapter V of SOLAS 1974 and sets minimum operational limits (e.g., operation between 70°S and 70°N and a minimum rate-of-turn capability of 20°/s for HSC dynamic requirements; 6°/s may apply when HSC requirements are not relevant).

This standard covers device architecture (sensing part, processor, transmitting part), required outputs, accuracy classes, installation features (fore‑and‑aft mark, non‑magnetic housing), and comprehensive type testing to demonstrate compliance.

Key Topics and Requirements

• Scope & Principle
  • Applies to THDs that depend on the Earth’s magnetic field (geomagnetic principle).
  • Distinguishes electromagnetic‑compass‑type (direct geomagnetic sensors) and magnetic‑compass‑type THDs (using standard magnetic compasses).
• Functionality & Information
  • All displays and outputs (except raw sensor) must indicate true heading.
  • Manual correction entries must be visibly indicated.
• Installation & Construction
  • Fore‑and‑aft mark on binnacle/housing to align unit on ship’s fore‑and‑aft line.
  • Non‑magnetic housing and defined electrical wiring/interface requirements.
• Accuracy & Performance
  • Defines static error, dynamic error, follow‑up error, transmission/resolution error and settling time requirements.
  • Includes requirements for correcting magnetic heading by magnetic variation, adjusting deviations and heeling error, and means for vertical soft‑iron correction.
• Type Tests
  • Mandatory tests: transmission error, static/follow‑up/dynamic accuracy, settling time, deviation adjustment, interface, malfunction and fore‑and‑aft mark tests.
• Marking & Identification
  • Requirements for labelling to ensure traceability and correct installation.

Applications and Users

Who benefits from ISO 22090-2:

• Shipbuilders and naval architects specifying heading systems.
• THD and compass manufacturers designing geomagnetic transmitters.
• Maritime system integrators (autopilot, INS, ECDIS, VDR).
• Classification societies, flag state surveyors and yards for SOLAS compliance.
• Operators of high‑speed craft (HSC) meeting dynamic heading requirements.

Practical applications:

• Providing certified heading inputs to autopilots, integrated navigation systems and bridge alert management.
• Ensuring SOLAS Chapter V compliance for heading sensors and transmission.
• Standardized testing and acceptance criteria for magnetic THD products.

Related Standards

• ISO 11606 (marine electromagnetic compasses)
• ISO 25862 (marine magnetic compasses)
• IEC 60945, IEC 61162‑1/‑2, IEC 61924‑2
• IMO Resolutions MSC.116(73), A.694(17), A.821(19), MSC.302(87)

Keywords: ISO 22090-2, transmitting heading devices, THD, geomagnetic THD, SOLAS, marine navigation, magnetic compass, heading accuracy, type tests.