On 20 June your vessel's 1955 ZT DR position is LAT 52°38.9'N, LONG 03°42.7'E, when an amplitude of the Sun is observed. The Sun's center is on the visible horizon and bears 311° per gyrocompass. Variation in the area is 6°W. At the time of the observation, the helmsman noted that he was heading 352° per gyrocompass and 358° per steering compass. What is the gyro error and deviation for that heading?

Question

On 20 June your vessel's 1955 ZT DR position is LAT 52&deg;38.9'N, LONG 03&deg;42.7'E, when an amplitude of the Sun is observed. The Sun's center is on the visible horizon and bears 311&deg; per gyrocompass. Variation in the area is 6&deg;W. At the time of the observation, the helmsman noted that he was heading 352&deg; per gyrocompass and 358&deg; per steering compass. What is the gyro error and deviation for that heading?

Accepted Answer

Option D: 1.3&deg;E GE, 1.3&deg;E DEV. Polaris azimuth or amplitude observations establish True bearings. Comparing the gyro bearing (311°) to the calculated True bearing yields gyro error. The compass error is the difference between the True bearing and the steering compass bearing. Subtracting variation from the compass error isolates the deviation for the specific heading of 358°.