Worksheet 5 · Skill 8
Light rising
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On a clear night your height of eye is 16 ft. You are closing a light listed as 45 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 11 ft. You are closing a light listed as 30 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 25 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 25 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 8 ft. You are closing a light listed as 40 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 19 ft. You are closing a light listed as 145 ft high, nominal range 9 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 13 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 9 ft. You are closing a light listed as 80 ft high, nominal range 22 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: 12.5 nm First seen at: 12.5 nm | No. 5001 (worked solution) |
| 2 | Geographic range: 10.3 nm First seen at: 10.3 nm | No. 5002 (worked solution) |
| 3 | Geographic range: 14.3 nm First seen at: 14.0 nm | No. 5003 (worked solution) |
| 4 | Geographic range: 14.3 nm First seen at: 14.0 nm | No. 5004 (worked solution) |
| 5 | Geographic range: 10.7 nm First seen at: 10.0 nm | No. 5005 (worked solution) |
| 6 | Geographic range: 19.2 nm First seen at: 9.0 nm | No. 5006 (worked solution) |
| 7 | Geographic range: 12.7 nm First seen at: 12.7 nm | No. 5007 (worked solution) |
| 8 | Geographic range: 14.0 nm First seen at: 14.0 nm | No. 5008 (worked solution) |