INTERNATIONAL & AMERICAN MAGNETIC COMPASS REQUIREMENTS
SOLAS V/19.2.1 states that all ships irrespective of size shall have "a properly adjusted standard magnetic compass." Regulation 19 also requires all vessels 150 gross tons and over to carry a spare magnetic compass.
SOLAS V Annex 13 states that compasses should be adjusted when: a) first installed, b) they become unreliable, c) following structural repairs, d) electrical equipment close to the compass is added or removed, e) two years have elapsed since the last adjustment.
IMO Resolution A.382(X) states that all ships be fitted with a magnetic compass, and that each compass should be “properly compensated” and the table of residual deviations be "available on board in the vicinity of the compass at all times." Annex II contains the universally accepted performance standards for compasses, and installation requirements including minimum distances between the compass and sources of magnetic interference (i.e. structural features & electronic equipment).
ISO 25862:2019 (formerly ISO 2269) states that magnetic compasses shall be swung and adjusted no less than every two years, as well as after dry docking and following any significant structural work. It also defines what constitutes a Class A magnetic compass (“intended for ship’s navigation and steering purposes in sea navigation”) vs a Class B compass (“intended for sea navigation on board ships for restricted service, lifeboats or rescue boats.”)
ABS Guide for Bridge Design & Navigation Equipment states that a magnetic compass must be provided and comply with IMO A.382(X).
Panama Canal Vessel Requirements (Notice to Shipping N01-2024, section 4.k on p.29) require vessels of 150 gross tons and over to have their compass deviation table renewed annually. Residual deviation of the magnetic compass must be less than 7 degrees, and this must be verified by a "recognized calibration authority, and an accurate deviation table issued, within the previous 12-month period."
US Code of Federal Regulations, 33 CFR 164.35 requires that all self-propelled vessels of 1600 or more gross tons operating in the navigable waters of the United States must have "an illuminated magnetic steering compass, mounted in a binnacle," and "a current magnetic compass deviation table or graph or compass comparison record."
US Code of Federal Regulations, 46 CFR Subchapter M 140.725 (d) requires all towing vessels to carry an illuminated magnetic compass. Also Subchapter M, 140.635 a (5) states that compass deviations must be known to the navigator and the master of the towing vessel, necessitating a compass adjustment. Towing vessels with LOA greater than 12 meters (39.4 feet) are also subject to 33 CFR 164.72. Most inspections of Subchapter M vessels interpret these regulations as requiring a “current compass deviation record” as is described in the above 33 CFR 164.35. (If a vessel engages in towing exclusively in Western Rivers, as defined here, it may opt for a swing meter instead of a magnetic compass.)
Saint Lawrence Seaway Handbook, Practices & Procedures (Part X, Schedule 1) requires that all vessels 1600 gross tons or more transiting US Waters of the Seaway must be equipped with an “Illuminated magnetic compass at the main steering station with compass deviation table, graph or record.” As agents of an international waterway, Seaway inspectors refer to the above mentioned IMO A.382(X) for their magnetic compass standards.
USCG MSIB 07-22 Survival Equipment Changes removes the requirement for survival craft/lifeboat magnetic compasses on US-flagged vessels to have Coast Guard type approval, as of December 2022. Instead the manufacturer is now required to self-certify that the compass complies with ISO 25862 (see above). This brings the US lifeboat compass standard in sync with the international lifeboat standard.