Chart Navigation & Plotting · Piloting — Vertical Sextant Angle
A lighthouse charted at 120 feet subtends a vertical sextant angle of 0°30'. Using distance(NM) = 0.565 × height(ft) ÷ angle(min), the distance off is:
- A4.52 NM
- B1.13 NM
- C2.26 NM✓ Correct
- D0.57 NM
Explanation
0°30' = 30'. Distance = 0.565 × 120 ÷ 30 = 67.8 ÷ 30 = 2.26 NM.
Authority: Bowditch (Pub. No. 9), Distance by Vertical Angle
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