Navigation General · Piloting & Bearings
A vessel is on course 000°T and observes a lighthouse bearing 045°T at 1200. At 1230, the vessel has run 5 nm and the lighthouse now bears 090°T. What is the distance off the lighthouse at 1230?
- A2.5 nm
- B7.1 nm
- C10.0 nm
- D5.0 nm✓ Correct
Explanation
The relative bearing changed from 045° (45° on the bow) to 090° (abeam), so this is a bow-and-beam bearing. The angle was NOT doubled (45° to 90° is doubling of the complement angle). This is actually a bow-and-beam: distance off at abeam = distance run = 5.0 nm.
Authority: Bowditch (Pub. 9), Ch. 8
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