On 10 June your vessel's 0519 zone time DR position is LAT 27°07.0'N, LONG 92°10.0'W, when an amplitude of the Sun is observed. The Sun's center is on the visible horizon and bears 063.6° per standard magnetic compass. The variation in the area is 4.8°E. The chronometer reads 11h 17m 32s and is 01m 18s slow. What is the deviation of the compass?

Question

On 10 June your vessel's 0519 zone time DR position is LAT 27&deg;07.0'N, LONG 92&deg;10.0'W, when an amplitude of the Sun is observed. The Sun's center is on the visible horizon and bears 063.6&deg; per standard magnetic compass. The variation in the area is 4.8&deg;E. The chronometer reads 11h 17m 32s and is 01m 18s slow. What is the deviation of the compass?

Accepted Answer

Option D: 4.8&deg;W. Calculate the Sun's declination for 10 June. Determine the true amplitude using sin(Amp) = sin(Dec) / cos(Lat). Convert the amplitude to a true bearing. Apply the 4.8°E variation to the compass bearing of 063.6°psc to find the magnetic bearing. The difference between the true and magnetic bearings results in 4.8°W deviation.