On 25 April your 1130 DR position is LAT 24° 50.0' N, LONG 61° 25.0' W. Your vessel is on a course of 300° T at a speed of 16.0 knots. Determine the zone time of (LAN) for your vessel.
• Local Apparent Noon (LAN) occurs when the Sun is exactly on your meridian (same longitude as the ship) • How to use Meridian Passage time from the Nautical Almanac (for 25 April) and convert it to your zone time using your time zone description (ZD) • How your course and speed between 1130 and LAN will change your longitude, which slightly shifts the LAN time
• From your DR longitude 61° 25.0' W, what is the nearest standard meridian for your time zone, and what is the correct Zone Description (ZD) sign and value? • Once you have the meridian passage time at Greenwich for 25 April, can you convert it to LAN at your standard meridian, and then further adjust it for your actual longitude? • As the ship is steaming on course 300°T at 16 knots, are you moving east or west, and will that motion make LAN occur earlier or later than the first time you compute? (Think about whether your longitude is increasing or decreasing.)
• Verify you used the correct ZD sign for west longitude when converting between GMT (UT) and Zone Time • Check that you converted the longitude difference to time correctly (4 minutes of time per degree of longitude; keep minutes of arc proportional) • Make sure you applied the vessel’s run between 1130 and LAN in longitude, not latitude, when refining the LAN time estimate
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