On 3 October your 0330 zone time (ZD + 5) DR position is LAT 47°41'N, LONG 86°49'W. At that time, you observe Polaris bearing 357.5°pgc. The chronometer time of the observation is 08h 32m 04s, and the chronometer is 0m 27s slow. The variation is 5.5°W. What is the gyro error?

Correct Answer: Option D — 2.0°E

Calculate GMT from chronometer time and error, then use local hour angle of Aries to correct Polaris pgc bearing to true bearing. The difference between true bearing and observed pgc bearing establishes the gyro error of 2.0°E, as outlined in Bowditch celestial navigation methods.