Over the curve of the water
Each height has its own distance to the horizon, 1.17 × √(feet) nautical miles. Add the two to get the geographic range.
Skill 8 · Light risingProblem 8008
Height of eye 17 ft: when should the light show?
On a clear night your height of eye is 17 ft. You are closing a light listed as 140 ft high, nominal range 16 nm.
Find its geographic range (how far off its light first clears the horizon for you) and the distance at which you should first see it. Take the nominal range as its luminous range on this clear night.
Use the horizon distance d = 1.17 × √h (nm, h in feet). Tolerance: 0.15 nm.
| Height of eye | 17 ft |
|---|---|
| Height of the light | 140 ft |
| Nominal range | 16 nm |
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