You are steaming on a course of 084°T at a speed of 13 knots. At 1919 a lighthouse bears 106.5°T. At 1957 the same lighthouse bears 129°T. What will be your distance off the lighthouse when abeam?

Correct Answer: Option B — 5.7 miles

The distance off when abeam is found by calculating the distance run between bearings and using the sine rule for the triangle formed by the vessel's track and the light. At 13 knots, the distance off at the second bearing is 5.7 miles, consistent with Bowditch piloting.