On 17 April your vessel's position is LAT 21°00'S, LONG 78°30'W, when an amplitude of the Sun is observed. The Sun's center is on the celestial horizon and bears 082.7° per standard magnetic compass. Variation in the area is 2.0°W. The chronometer reads 10h 59m 24s and is 01m 24s fast. What is the deviation of the compass?

Question

On 17 April your vessel's position is LAT 21&deg;00'S, LONG 78&deg;30'W, when an amplitude of the Sun is observed. The Sun's center is on the celestial horizon and bears 082.7&deg; per standard magnetic compass. Variation in the area is 2.0&deg;W. The chronometer reads 10h 59m 24s and is 01m 24s fast. What is the deviation of the compass?

Accepted Answer

Option A: 2.0&deg;W. Calculate the Sun's true amplitude using the formula sin(Amp) = sin(Dec) / cos(Lat). With the corrected chronometer time, determine the Sun's declination from the Nautical Almanac. Comparing the calculated true amplitude to the compass bearing, adjusted for 2.0°W variation, reveals a compass deviation of 2.0°W.