Your vessel is underway on a course of 323.5°T at a speed of 16 knots. At 1945 a light bears 350°T. At 2010 the light bears 008.5°T. What will be your distance off when abeam of the light?

Correct Answer: Option A — 6.7 miles

Apply the 'bow and beam' or 'doubling the angle' principle. The change in bearing from 350° to 008.5° (a 18.5° change) over 25 minutes allows for calculating the distance run. Using the distance run and the relative bearings, the distance off when abeam is 6.7 miles.