Worksheet 11 · Skill 8
Light rising
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On a clear night your height of eye is 23 ft. You are closing a light listed as 100 ft high, nominal range 6 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 15 ft. You are closing a light listed as 55 ft high, nominal range 19 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 20 ft. You are closing a light listed as 135 ft high, nominal range 15 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 8 ft. You are closing a light listed as 135 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 21 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 14 ft. You are closing a light listed as 85 ft high, nominal range 10 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 12 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 a light listed as 155 ft high, nominal range 10 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
Answer key
| No. | Answers | Problem |
|---|---|---|
| 1 | Geographic range: 17.3 nm First seen at: 6.0 nm | No. 11001 (worked solution) |
| 2 | Geographic range: 13.2 nm First seen at: 13.2 nm | No. 11002 (worked solution) |
| 3 | Geographic range: 18.8 nm First seen at: 15.0 nm | No. 11003 (worked solution) |
| 4 | Geographic range: 16.9 nm First seen at: 16.9 nm | No. 11004 (worked solution) |
| 5 | Geographic range: 13.8 nm First seen at: 13.8 nm | No. 11005 (worked solution) |
| 6 | Geographic range: 15.2 nm First seen at: 10.0 nm | No. 11006 (worked solution) |
| 7 | Geographic range: 12.5 nm First seen at: 12.5 nm | No. 11007 (worked solution) |
| 8 | Geographic range: 17.4 nm First seen at: 10.0 nm | No. 11008 (worked solution) |