On 16 September your vessel's 0736 zone time DR position is LAT 27°34'S, LONG 174°49'E, when an azimuth of the Sun is observed. The chronometer time of the sight is 07h 38m 11s, and the Sun is bearing 079.8° per gyrocompass. The chronometer error is 01m 46s fast, and the variation in the area is 11.0°W. At the time of the sight, the helmsman reports that he was heading 252°pgc and 258° per magnetic compass. What is the deviation of the magnetic compass?
Official USCG Answer & Rule Citation
Correct Answer: Option C — 3°E
Sun azimuth sight reduction establishes the true bearing of the celestial body. Applying gyro error, variation, and magnetic heading comparisons according to standard piloting rules determines the magnetic compass deviation of 3°E for the given heading.
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