Question 225Navigation General

70% to pass

The Light List shows that a navigational light has a nominal range of 12 miles and a height above water of 25 feet (7.6 meters). Your height of eye is 30 feet (9.1 meters) and the visibility is 0.5 mile. At what approximate range will you first sight the light?

A 1.4 miles
B 12.0 miles
C 0.5 mile
D 5.2 miles
AI Explanation

The correct answer is A) 1.4 miles. The reason this is the correct answer is that the range at which you will first sight the navigational light depends on the height of the light above the water and your own height of eye, as well as the visibility. Using the formula for the geographic range of a light, the approximate range at which you will first sight the light is 1.4 miles. The other options are incorrect because B) 12.0 miles is the nominal range of the light, not the actual range at which you will see it; C) 0.5 mile is the given visibility, not the sighting range; and D) 5.2 miles is an incorrect calculation of the sighting range.

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Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG National Maritime Center
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