You wish to check the deviation of your standard magnetic compass. You find a natural range that you steer for and note that the gyrocompass heading is 034°, and the heading by standard magnetic compass is 026°. The gyro error is 1°W. Variation is 9°E. What is the deviation for that heading?

Correct Answer: Option B — 2°W

True heading is derived from the gyro reading combined with gyro error (034° - 1°W = 033°T). Applying variation (9°E) to true heading yields magnetic heading (024°m). Comparing magnetic heading with standard compass reading (026°psc) determines a deviation of 2°W.