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 10007
Height of eye 4 ft: when should the light show?
On a clear night your height of eye is 4 ft. You are closing a light listed as 130 ft high, nominal range 7 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 | 4 ft |
|---|---|
| Height of the light | 130 ft |
| Nominal range | 7 nm |
Plot Pass skill. Plot Pass $1.95/month or $19.50/year · Free during preview: all eight skills, worksheets with answer keys, a 5,000-attempt Plot Log and CSV.