What is Deviation in compass terms?

• A. Error in chart scale
• B. Error from boat's magnetic influences
• C. Error from water current
• D. Error due to wind drift

Answer: (B)

Deviation is the error in a compass reading caused by the vessel’s own magnetic and ferrous influences. The kayak, paddles, fittings, and onboard gear create local magnetic fields that tug on the compass needle, so the reading won’t point exactly to magnetic north. This is different from variation, which is the natural difference between true north and magnetic north at a location. Deviation is specific to each boat and can be worked out by swinging the compass and using a deviation card to apply the correction. In practice, you adjust your bearings by the known deviation so your compass shows the true magnetic direction, which you then reconcile with variation as needed. Wind drift and water current affect where you end up relative to your intended track, but they don’t change the compass’s internal reading, and chart scale errors are separate charting issues.