On 15 October your 0325 zone time DR position is LAT 26°51.0' N, LONG 138°17.0' W. At that time, you observe Canopus bearing 167°pgc. The chronometer reads 00h 25m 36s, and the chronometer error is 00m 20s slow. The variation is 2°E. What is the gyro error?

Correct Answer: Option D — 1.3°W

Greenwich Mean Time is derived from chronometer time and error. Entering the Nautical Almanac with GMT yields sidereal hour angle and declination for Canopus. Solving the navigational triangle gives true bearing, which compared with gyro bearing results in 1.3°W gyro error.