USCG Exam PracticePlot true course and distance between two charted points
Using the doubling-the-angle technique, a vessel takes a relative bearing of 030° to a lighthouse, then continues on course until the relative bearing doubles to 060°. What does the distance run between the two bearings equal?
- A. The distance to the lighthouse at the time of the first bearing
- ✓ The distance to the lighthouse at the time of the second bearingCorrect
- C. Twice the distance to the lighthouse at the time of the second bearing
- D. The distance to the lighthouse at the mid-point between the two bearings
Why B is correct
Bowditch Ch. 7 §703 states that in the doubling-the-angle technique, the distance run between the two bearings equals the distance to the object at the second bearing. This allows the navigator to determine the vessel's distance off at the time of the second observation.
Cited:Bowditch Ch. 7 §703