Which term describes the compass error caused by the boat's own magnetic influences?

• A. Drift
• B. Variation
• C. Deviation angle
• D. Deviation

Answer: (D)

Deviation is the compass error caused by the boat’s own magnetic influences. The vessel’s metalwork, equipment, and magnetic fields from the boat itself pull the compass away from true magnetic north, creating a deviation that is measured as a deviation angle in degrees. This is separate from variation, which is the difference between magnetic north and true north due to Earth’s magnetic field at your location, and from drift, which is being pushed off course by wind or current. So the error arising from the boat’s own magnetism is called deviation.