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 true heading of 319°.

Correct Answer: Option D — 2.5°E

Applying compass error relationships, true heading equals gyro heading plus gyro error (319° + (-2°)) giving 317°T. Magnetic heading equals true heading minus variation (317° - (-8°)) giving 325°m. Comparing magnetic heading with standard compass heading yields a deviation of 2.5°E.