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 039°.

Correct Answer: Option B — 1.0°W

True heading is established by applying gyro error (2°W) to the gyro heading (039° - 2° = 037°T). Magnetic heading is derived by applying variation (8°W) to true heading (37° + 8° = 045°M). Comparing magnetic heading with the compass heading gives deviation of 1.0°W.