On 23 July your 2100 ZT position is LAT 36°43.0'N, LONG 16°09.8'W, when you observed an azimuth of Polaris to determine the compass error. Polaris bears 359.0° per gyrocompass. At the time of the observation, the helmsman noted that he was heading 319.0° per gyrocompass and 331.0° per standard compass. Variation is 12.0°W. Which of the following statements is TRUE?

Question

On 23 July your 2100 ZT position is LAT 36&deg;43.0'N, LONG 16&deg;09.8'W, when you observed an azimuth of Polaris to determine the compass error. Polaris bears 359.0&deg; per gyrocompass. At the time of the observation, the helmsman noted that he was heading 319.0&deg; per gyrocompass and 331.0&deg; per standard compass. Variation is 12.0&deg;W. Which of the following statements is TRUE?

Accepted Answer

Option C: The deviation is 1.7&deg;E.. Polaris azimuth tables provide the True bearing. Comparing this to the gyro bearing (359°) gives the gyro error. The compass error is the difference between the True bearing and the standard compass bearing. Subtracting variation from the compass error isolates the deviation, which is calculated as 1.7°E for this heading.