On 17 November your 1530 ZT DR position is LAT 27° 13.0' S, LONG 153° 21.0' W. You are on course 261° T at a speed of 14 knots. What will be the ZT of sunset at your vessel?
• Use the Nautical Almanac sunset tables for the correct date and latitude • Apply the zone description (ZD) and longitude-to-time conversion to relate GMT and ZT • Account for the vessel’s run between DR time and sunset when finding the final ZT
• What is the approximate UT (GMT) of sunset for latitude 27° S on 17 November, and how do you interpolate for your exact latitude? • How many minutes of time difference does your longitude represent from the standard meridian for your time zone, and in which direction (earlier or later)? • Between 1530 ZT and the estimated sunset time, how far will the vessel travel along course 261° T, and how will this change your longitude for the final calculation?
• Confirm you are using the correct ZD sign for west longitudes when converting between ZT and GMT • Verify the longitude at the actual time of sunset, not just the 1530 DR position • Double-check that your time differences (in hours and minutes) from speed and distance are computed consistently in units (nm and knots)
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