Navigation Problems USCG Question #311 (Set 8)

On 4 July at 0630 ZT, morning stars were observed, and the vessel's position was determined to be LAT 21°15.0'S, LONG 21°20.0'W. Your vessel is steaming at 13.0 knots on a course of 146°T. A sextant observation of the Sun's lower limb is made at 0915 ZT. The chronometer reads 10h 14m 27s, and the sextant altitude is 25°29.8'. The index error is 3.1' off the arc, and the chronometer error is 0m 53s slow. Your height of eye on the bridge is 48.0 feet. What is the azimuth (Zn) of this sight using the assumed position?

Official USCG Answer & Rule Citation

Correct Answer: Option A — 049.5°T

Using the chronometer time to find the Greenwich Hour Angle and the assumed position to find the Local Hour Angle, the azimuth is calculated via the navigational triangle. The resulting azimuth is 049.5°T, consistent with standard celestial navigation practices.

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