At 0400 zone time on 24 June, your DR position is LAT 23° 10.0' N, LONG 085° 33' W. You are steering 295° T at a speed of 10.0 knots. What is the zone time of sunrise?
• Use of the Nautical Almanac sunrise tables for the correct date and latitude • Application of zone description (ZD) to convert between GMT (UT) and zone time • Effect of longitude on sunrise time relative to the standard meridian of the time zone
• From the given DR position, which time zone and zone description (ZD) are you in based on your longitude? • After you find sunrise in GMT (UT) for the nearest tabulated latitude, how do you correctly adjust for your exact longitude east or west of the time zone meridian? • Is your course and speed between DR time and sunrise large enough to significantly change your assumed position for the sunrise calculation?
• Confirm the correct ZD sign (plus or minus) for 85° W longitude • Make sure you are using 24 June data in the almanac, not the adjacent date • Double-check that any interpolation for latitude and longitude moves sunrise in the correct direction (earlier vs later)
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