The Light List indicates that a light has a nominal range of 18 miles and is 38 feet high. If the visibility is 6 miles and your height of eye is 15 feet, at which distance will you sight the light?

Correct Answer: Option C — 11.7 nm

Geographic range is 1.17 * sqrt(38) + 1.17 * sqrt(15), equaling 7.2 + 4.5 = 11.7 nm. Since the visibility is 6 miles, the luminous range is the limiting factor. The light will be sighted at the distance of the visibility, approximately 11.7 nm.