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?

Question

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&deg;, and the heading by standard magnetic compass is 026&deg;. The gyro error is 1&deg;W. Variation is 9&deg;E. What is the deviation for that heading?

Accepted Answer

Option A: 2&deg;W. Gyro error of 1°W applied to 034°pgc gives a true bearing of 033°T. With variation 9°E, the magnetic heading is 024°M. Comparing the standard magnetic compass heading of 026°psc to the magnetic heading of 024°M reveals a deviation of 2°W, as compass is least.