Navigation General · Piloting & Bearings
A vessel is on course 270°T and observes a lighthouse at a relative bearing of 30° on the port bow. Later, the same lighthouse bears 60° on the port bow. The vessel ran 5 nm between observations. What is the distance off the lighthouse at the time of the SECOND bearing?
- A2.5 nm
- B8.7 nm
- C5.0 nm✓ Correct
- D10.0 nm
Explanation
The angle on the bow doubled from 30° to 60°. By the rule of doubling the angle on the bow, the distance off at the second bearing equals the distance run between the two bearings = 5.0 nm.
Authority: Bowditch (Pub. 9), Ch. 8
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