Magnetic compass adjustment and deviation card rules

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The magnetic compass is the oldest instrument on the bridge and the only heading reference that keeps working when every generator has stopped. That is why SOLAS still requires a “properly adjusted” standard magnetic compass on every ship, and why surveyors and port State control officers still ask to see the deviation card and the compass book.

It is also the instrument most likely to be neglected. Gyros and GNSS do the daily work, the compass gets a glance, and the deviation card on the bulkhead can be years old and drawn for a different ship condition. In 2015 a consultancy circular reported a cargo ship that received the deficiency “magnetic compass not properly adjusted” during a detailed port State control inspection in Canada. This lesson explains when adjustment is needed, who may do it, and how to show that your compass can be trusted.

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In this lesson

Try it: Should the compass be adjusted?
In plain words
In detail
What the rules say
Flag and class notes
Key numbers
What inspectors find
Work it out: a calculator
Questions people ask
Quiz: 6 questions

Sources

1 SOLAS 1974, as amended, chapter V, regulation 19, paragraphs 2.1.1 to 2.1.3 and 2.2.1. IMO consolidated edition (sales publication). https://www.imo.org/en/About/Conventions/Pages/International-Convention-for-the-Safety-of-Life-at-Sea-(SOLAS),-1974.aspx
2 Maritime and Coastguard Agency, MGN 610 (M+F), SOLAS Chapter V guidance, Annex D: Magnetic compasses (operation, maintenance and testing; adjustment of compasses; adjustments and repairs; transmitting magnetic compasses). https://assets.publishing.service.gov.uk/media/5f2140d3e90e071a603d33b3/MGN_610_2020.pdf
3 IMO Resolution A.382(X), Magnetic compasses carriage and performance standards (adopted 14 November 1977), annex I paragraph 3 and annex II paragraphs 2.2 and 6.1. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/AssemblyDocuments/A.382(10).pdf
4 IMO Resolution A.1207(34), Survey Guidelines under the Harmonized System of Survey and Certification (HSSC), 2025, annex, paragraphs (EI) 1.1.4.31, 1.1.4.33.1, 1.1.4.33.6 and (EA) 1.2.1.20. https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2034-Res.1207%20-%20SURVEY%20GUIDELINES%20UNDER%20THE%20HARMONIZED%20SYSTEMOF%20SURVEY%20AND%20CERTIFICATION%20(HSSC),%202025%20(Secretariat).pdf
5 Panama Maritime Authority, Merchant Marine Circular No. 138, Magnetic Compass, paragraphs 4 and 7 (text read: earlier edition published on the registry website; revised April 2024). https://panamashipregistry.com/wp-content/uploads/2019/03/138.pdf
6 Isle of Man Ship Registry, Manx Shipping Notice MSN 007, Magnetic compass adjustment and records of deviations (February 2007), paragraphs 2 to 8, quoting STCW Code section A-VIII/2. https://iomshipregistry.com/media/1376/msn-007-magnetic-compass-adjustment-and-records-of-deviations.pdf
7 Australian Maritime Safety Authority, Marine Notice 19/2016, Maintenance and adjustment of magnetic compasses, quoting ISO 25862:2009 Annex G (copy published by Indian Register of Shipping). https://www.irclass.org/media/2537/encl-1-amsa-marine-notice-no19-2016.pdf
8 Maritime and Coastguard Agency, MGN 279 (M), Certificate of Competency as Compass Adjuster (October 2004), paragraphs 1 to 4 and appendix (syllabus). https://assets.publishing.service.gov.uk/media/5a7cd66be5274a2c9a4846a2/mgn279.pdf
9 Prevention at Sea, Circular 02/06/2015, “Magnetic compass not properly adjusted” – important safety and PSC issue. https://www.preventionatsea.com/assets/public/files/DCP%20-%20Circular%2002-06-15%20-%20Magnetic%20Compass%20not%20properly%20adjusted%20-%20Important%20Safety%20&%20Port%20State%20Control%20Issue!.pdf

Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.

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