Worksheet 15 · Skill 8
Light rising
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On a clear night your height of eye is 9 ft. You are closing a light listed as 100 ft high, nominal range 21 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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 7 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 22 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 4 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 17 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 6 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 5 ft. You are closing a light listed as 125 ft high, nominal range 20 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.
Geographic range: ________ nm First seen at: ________ nm
On a clear night your height of eye is 7 ft. You are closing Heron Point Light (Fl W 4s 52ft 14M).
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.
Geographic range: ________ nm First seen at: ________ nm
Answer key
| No. | Answers | Problem |
|---|---|---|
| 1 | Geographic range: 15.2 nm First seen at: 15.2 nm | No. 15001 (worked solution) |
| 2 | Geographic range: 11.5 nm First seen at: 11.5 nm | No. 15002 (worked solution) |
| 3 | Geographic range: 13.9 nm First seen at: 13.9 nm | No. 15003 (worked solution) |
| 4 | Geographic range: 10.8 nm First seen at: 10.8 nm | No. 15004 (worked solution) |
| 5 | Geographic range: 13.3 nm First seen at: 13.3 nm | No. 15005 (worked solution) |
| 6 | Geographic range: 11.3 nm First seen at: 11.3 nm | No. 15006 (worked solution) |
| 7 | Geographic range: 15.7 nm First seen at: 15.7 nm | No. 15007 (worked solution) |
| 8 | Geographic range: 11.5 nm First seen at: 11.5 nm | No. 15008 (worked solution) |