Question 72Navigation Problems
70% to passOn 12 April at 0515 ZT, morning stars were observed, and the vessel's position was determined to be LAT 21°05'S, LONG 16°30'W. Your vessel is steaming at 19 knots on a course of 278°T. A sextant observation of the Sun's lower limb is made at 0930 ZT. The chronometer reads 10h 28m 25s, and the sextant altitude (hs) is 40°15.9'. The index error is 2.5' off the arc, and the chronometer error is 2m 15s slow. Your height of eye on the bridge is 57 feet. What are the intercept (a) and azimuth (Zn) from the assumed position of this sight?
The correct answer is D) Zn 057.0°, a 17.7' A. The explanation is as follows: 1. Confirm which answer is correct: Option D is the correct answer, with the azimuth (Zn) as 057.0° and the intercept (a) as 17.7' A. 2. Explain the reasoning: To determine the intercept (a) and azimuth (Zn), the sight reduction process is used, which involves calculating the Assumed Position (AP), the Observed Altitude (Hs), and the Computed Altitude (Hc). The data provided, including the vessel's position, course, speed, sextant observation, and chronometer error, is used in these calculations to arrive at the correct intercept (a) and azimuth (Zn). 3. Why the other options are incorrect: Options A, B, and C provide different values for the intercept (a) and azimuth (Zn), which do not match the correct solution obtained through the sight reduction process. 4. Concise explanation: The correct answer of Zn 057.0°, a 17.7' A is obtained through the proper application of the sight reduction process, using the given information about the vessel's position, course, speed, and sextant observation, as well as the chronometer error.
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