At 1544 zone time on 5 October your DR position is LAT 25° 00' N, LONG 60° 15' W. You are steering 270° T at a speed of 6.8 knots. What is the zone time of sunset?
• Use the Nautical Almanac sunset tables for the correct date and latitude band • Convert between Local Mean Time (LMT) of sunset and Zone Time (ZT) using longitude and zone description (ZD) • Account for the vessel’s DR position at the time of sunset, not just at 1544
• From LAT 25° 00' N on 5 October, what is the LMT of sunset from the Almanac, and how do you interpolate if 25° is between tabulated latitudes? • How does LONG 60° 15' W relate to the standard time meridian for your time zone, and what ZD (zone description) does that imply? • Given course 270° T and 6.8 knots, how far will you travel (in longitude/position change) between 1544 and the approximate sunset time, and does that change the longitude enough to matter for your ZT calculation?
• Be sure you are using local mean time (LMT) at your DR longitude, not GMT/UT, when comparing to sunset tables • Confirm the correct sign and value of ZD for west longitude when converting LMT to ZT • Verify whether the change in longitude due to DR run between now and sunset is significant for the final ZT choice among the options
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