USCG Exam PracticePlot true course and distance between two charted points
A navigator takes a bearing of 045°T on a lighthouse and notes the time. The vessel continues on course, and after running a measured distance, takes a second bearing of 090°T on the same lighthouse. The navigator advances the first LOP along the DR track to the time of the second bearing. What type of position does the intersection of the advanced LOP and the second LOP produce?
- A. A fix, because two LOPs from the same object always produce a fix
- B. A dead reckoning position, because no external reference was used
- ✓ A running fix, which is less accurate than a fix from simultaneous LOPsCorrect
- D. A doubling-the-angle fix, which is more accurate than a simultaneous fix
Why C is correct
Bowditch Ch. 7 §702 defines a running fix as one obtained when LOPs cannot be taken simultaneously; the first LOP is advanced along the DR track to the time of the second observation, and the result is less accurate than a simultaneous fix because DR errors accumulate during the interval.
Cited:Bowditch Ch. 7 §702