USCG Exam PracticeRunning fix from a single object
A navigator observes a relative bearing of 30° on a lighthouse and notes the time and log reading. The vessel continues on the same course and speed until the relative bearing to the same lighthouse reads 60°. Using the doubling-the-angle technique, what is the vessel's distance off the lighthouse at the time of the second bearing?
- A. Half the distance run between the two bearings
- B. Twice the distance run between the two bearings
- ✓ Equal to the distance run between the two bearingsCorrect
- D. Equal to the distance run multiplied by the sine of the first bearing angle
Why C is correct
Bowditch Ch. 7 §703 states that in the doubling-the-angle technique, the distance run between the two relative bearings equals the distance to the object at the second bearing. Since 60° is double 30°, the distance off at the second bearing equals the distance run in the interval.
Cited:Bowditch Ch. 7 §703