Worksheet 20 · Skill 8
Light rising
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On a clear night your height of eye is 8 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 130 ft high, nominal range 14 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 9 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 21 ft. You are closing a light listed as 115 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 5 ft. You are closing a light listed as 95 ft high, nominal range 18 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 23 ft. You are closing a light listed as 110 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 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
Answer key
| No. | Answers | Problem |
|---|---|---|
| 1 | Geographic range: 11.7 nm First seen at: 11.7 nm | No. 20001 (worked solution) |
| 2 | Geographic range: 16.9 nm First seen at: 14.0 nm | No. 20002 (worked solution) |
| 3 | Geographic range: 11.5 nm First seen at: 11.5 nm | No. 20003 (worked solution) |
| 4 | Geographic range: 11.9 nm First seen at: 11.9 nm | No. 20004 (worked solution) |
| 5 | Geographic range: 17.9 nm First seen at: 17.9 nm | No. 20005 (worked solution) |
| 6 | Geographic range: 14.0 nm First seen at: 14.0 nm | No. 20006 (worked solution) |
| 7 | Geographic range: 17.9 nm First seen at: 6.0 nm | No. 20007 (worked solution) |
| 8 | Geographic range: 11.3 nm First seen at: 11.3 nm | No. 20008 (worked solution) |