USCG Exam PracticeDanger bearings and danger circles
A navigator is approaching a headland with a single lighthouse visible. She plans to use the doubling-the-angle technique to obtain a running fix and simultaneously verify her clearance from a reef using a danger bearing to the same lighthouse. The danger bearing is labelled 'NLT 050°T'. At the moment she takes her second bearing, the relative bearing has doubled and the observed compass bearing is 048°T. Which statement correctly evaluates both the running fix and the danger bearing status?
- ✓ The running fix is valid because the angle doubled; the vessel is on the dangerous side of the danger bearing because 048°T is less than 050°TCorrect
- B. The running fix is valid because the angle doubled; the vessel is in safe water because 048°T is less than 050°T
- C. The running fix is invalid because a danger bearing cannot be used as the second LOP in a doubling-the-angle technique
- D. The vessel is in safe water because the danger bearing requires the observed bearing to be not more than 050°T
Why A is correct
Bowditch Ch. 7 §703 confirms the doubling-the-angle technique yields a valid running fix when the relative bearing doubles. Bowditch Ch. 7 §706 defines NLT (not less than) 050°T as requiring the observed bearing to be 050°T or greater to remain safe; an observed bearing of 048°T falls below that threshold, placing the vessel on the dangerous side of the danger bearing.