On 26 January your 1615 ZT DR position is LAT 27°14.0'S, LONG 57°22.0'W. At that time, you observe the Sun bearing 266°psc. The chronometer reads 08h 13m 19s, and the chronometer error is 01m 46s slow. The variation is 4°E. What is the deviation of the standard magnetic compass?

Correct Answer: Option D — 5.9°W

Find GMT by applying chronometer error, determine LHA using DR longitude, and solve the navigational triangle to obtain the true azimuth. Compare true azimuth to the observed standard compass bearing to establish compass error, then apply variation to isolate the magnetic compass deviation.