Chart Navigation & Plotting · Distance Off — Doubling the Angle on the Bow
A landmark bears 30° on the bow; later it bears 60° on the bow. You ran 5.0 NM between the bearings. What is your distance from the landmark at the second (60°) bearing?
- A2.5 NM
- B5.0 NM✓ Correct
- C10.0 NM
- D7.1 NM
Explanation
Doubling the angle on the bow (here 30° then 60°) forms an isosceles triangle in which the distance run equals the distance off at the second bearing: 5.0 NM. The method works for any pair where the second relative angle is twice the first.
Authority: Bowditch (Pub. No. 9), Distance by Two Bearings
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