Deviation is caused by?

• A. Weather and Sea State
• B. The Color of Hull
• C. Engine Room, Cargo, and Any Metallic Modifications to That Vessel
• D. The Crew's Experience

Answer: (C)

Deviation is the compass error caused by the ship’s own magnetic field. The engine room, cargo, and any metallic modifications on the vessel create localized magnetic fields that tug on the compass needle, shifting readings away from magnetic north. Because these magnetic influences come from the vessel’s structure and equipment and change with how the ship is configured and on different headings, deviation varies and must be measured and corrected with a deviation card or by adjusting the compass.

Weather and sea state don’t create this internal distortion, nor do the hull’s color or the crew’s experience, so they aren’t sources of deviation.