Chart Navigation & Plotting · Piloting — Distance to Horizon
With a height of eye of 49 feet, what is your distance to the visible horizon using 1.17 × √height (feet)?
- A4.1 nautical miles
- B5.7 nautical miles
- C11.7 nautical miles
- D8.2 nautical miles✓ Correct
Explanation
1.17 × √49 = 1.17 × 7 = 8.19 ≈ 8.2 nm. This is the same constant used in geographic-range calculations; the horizon distance grows with the square root of the height of eye.
Authority: Bowditch (Pub. No. 9), distance to the horizon
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