On Sunday, 8 November, your ship is enroute from Texas City, TX, to Portland, ME. At 0632 ZT, you fix your position at LAT 27°06'N, LONG 90°36'W. When the lower limb of the Sun was two-thirds of a diameter above the visible horizon, the Sun bore 105° per standard magnetic compass. At this time the chronometer read 12h 39m 20s and is 3m 20s slow. If the variation is 3°E, determine the deviation of the standard compass.

Question

On Sunday, 8 November, your ship is enroute from Texas City, TX, to Portland, ME. At 0632 ZT, you fix your position at LAT 27&deg;06'N, LONG 90&deg;36'W. When the lower limb of the Sun was two-thirds of a diameter above the visible horizon, the Sun bore 105&deg; per standard magnetic compass. At this time the chronometer read 12h 39m 20s and is 3m 20s slow. If the variation is 3&deg;E, determine the deviation of the standard compass.

Accepted Answer

Option A: 0.8&deg;E. Determine the Sun's declination and LHA via the Nautical Almanac. Calculate the true amplitude using the amplitude formula, correcting for the Sun's altitude. Comparing the true amplitude to the magnetic bearing (105°) and applying the 3°E variation reveals a deviation of 0.8°E.