Navigation General · Time — Zone Description
A vessel's chronometer or master clock for celestial/communications work is normally kept on:
- ALocal apparent time
- BCoordinated Universal Time (UTC/GMT)✓ Correct
- CShip's mealtime
- DEngine-room time
Explanation
UTC (essentially GMT) is the universal reference for celestial navigation, the Nautical Almanac, and radio/safety communications. Zone time is UTC adjusted by the zone description (longitude ÷ 15, rounded), and is what the ship's clocks are set to locally.
Authority: Bowditch; Nautical Almanac
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