If the deviation gets greater than how many degrees should you hire a magnetic compass adjuster?

• A. 5 Degrees
• B. 8 Degrees
• C. 12 Degrees
• D. 10 Degrees

Answer: (D)

Deviation is the error in a magnetic compass caused by the ship’s own magnetic field, and it changes with the vessel’s heading. When that error becomes large, relying on routine bridge adjustments won’t guarantee accurate readings across all headings, so a professional compass adjuster is needed to recalibrate the instrument and produce a new deviation card. The standard trigger is when deviation exceeds ten degrees; at or beyond this level the reliability of navigation readings on all headings is compromised and must be corrected by a specialist. Smaller deviations, like five or eight degrees, can usually be addressed through regular maintenance and adjustments, while a deviation as large as twelve degrees would also justify adjustment, the established practice reference looks to ten degrees as the threshold.