You swung ship and compared the magnetic compass against the gyro compass to find deviation. Gyro error is 2°W. The variation is 8°W. Find the deviation on a gyro heading of 058°.

Correct Answer: Option A — 1.5°W

True heading is derived from gyro heading corrected for gyro error (058° - 2°W = 056°T). Magnetic heading is derived using variation (056°T + 8°W = 064°M). The difference between magnetic heading and compass heading (058°psc) gives a deviation of 1.5°W, as compass best represents least.