On 23 October your vessel's 1722 zone time DR position is LAT 27°36'S, LONG 96°16'W, when an amplitude of the Sun is observed. The Sun's lower limb is about 20 minutes of arc above the visible horizon and bears 246° per standard compass. Variation in the area is 14.0°E. The chronometer reads 11h 24m 19s and is 01m 43s fast. What is the deviation of the standard compass?

Question

On 23 October your vessel's 1722 zone time DR position is LAT 27&deg;36'S, LONG 96&deg;16'W, when an amplitude of the Sun is observed. The Sun's lower limb is about 20 minutes of arc above the visible horizon and bears 246&deg; per standard compass. Variation in the area is 14.0&deg;E. The chronometer reads 11h 24m 19s and is 01m 43s fast. What is the deviation of the standard compass?

Accepted Answer

Option D: 3.1&deg;W. Calculate the Sun's declination and local hour angle using the Nautical Almanac. Determine the true amplitude using the formula sin(Amp) = sin(Dec) / cos(Lat). Compare the true amplitude to the compass bearing, adjusting for variation and the observed altitude correction, to isolate the deviation as 3.1°W.