Question 415Navigation 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 38 feet (11.6 meters) and the visibility is 5.5 miles. At what approximate range will you FIRST sight the light?

A 5.5 miles
B 6.3 miles
C 8.0 miles
D 12.0 miles
AI Explanation

The correct answer is C) 8.0 miles. The range at which you will first sight the navigational light is determined by the concept of geometric or optical horizon. This is the maximum distance at which an object can be seen on the horizon, given the observer's height of eye and the object's height above the water. Using the formula for geometric horizon distance, and the provided values of height of eye (38 feet) and light height (25 feet), the calculated distance is approximately 8.0 miles. This makes C the correct answer. The other options are incorrect because they do not accurately reflect the geometric horizon distance calculation for the given parameters.

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