Celestial Navigation · Time — Zone Description
Your DR longitude is 100°W. What is the zone description?
- A+7 (add 7 hours to ZT)✓ Correct
- B−7 (subtract 7 hours)
- C+6 (one zone too few)
- D+100 (that is the longitude, not a ZD)
Explanation
100 ÷ 15 = 6.67, rounded to 7. West longitude is positive: ZD = +7 (add 7 hours to zone time for GMT).
Authority: Bowditch (Pub. No. 9), Time
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