On 1 November your 1600 zone time DR position is LAT 27°48'S, LONG 91°26'E. Your vessel is on a course of 327°T at a speed of 16 knots. What will be the zone time of sunset at your vessel?
• Zone time vs. GMT/UT and how longitude affects time of sunrise/sunset • Run between DR position and assumed longitude/standard meridian for the time zone • Using the Nautical Almanac sunset tables for the correct latitude and date
• How do you find the approximate zone description (time zone) for longitude 91°26'E, and what standard meridian does that correspond to? • Once you know the zone description, what adjustments must you make between GMT sunset time from the Nautical Almanac and the local zone time at the ship? • How does the vessel’s movement between 1600 ZT and the time of sunset affect the longitude you should use for the sunset calculation?
• Confirm the correct time zone/zone description from the given longitude before looking up any times • Use the correct latitude band in the Nautical Almanac sunset tables for 1 November (S vs N and nearest whole degree or tabular interval) • Apply the run correction for the vessel’s motion along the course between 1600 and sunset before converting to final zone time
No comments yet
Be the first to share your thoughts!