Chart Navigation & Plotting · Distance Off — Bow and Beam Bearings
A light is observed 45° on the bow, then again when abeam (90° relative). You ran 5.2 NM between the bearings. The distance off when abeam is:
- A5.2 NM✓ Correct
- B2.6 NM
- C7.4 NM
- D10.4 NM
Explanation
Bow-and-beam bearings (45° and 90° relative) form an isosceles right triangle, so the distance off when abeam equals the run between bearings: 5.2 NM.
Authority: Bowditch (Pub. No. 9), Distance by Two Bearings
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