USCG Exam PracticeDanger bearings and danger circles
A navigator is transiting a channel with a single lighthouse visible. She takes a bearing of 035°T, runs 1.5 nm on course 090°T, then takes a second bearing of 355°T to the same lighthouse. She advances the first LOP along the DR track and plots the intersection. What type of position has she obtained, and what is its primary limitation?
- A. A simultaneous fix; it is limited by the accuracy of the compass
- ✓ A running fix; it is less reliable because it assumes course and speed were held exactly between observationsCorrect
- C. A danger bearing solution; it is limited to keeping the vessel on the safe side of a single line
- D. A three-bearing fix; the cocked hat may be large if the object is not well separated
Why B is correct
Bowditch Ch. 7 §708 describes exactly this procedure as a running fix and states it is less reliable than a simultaneous two-object fix because it assumes course and speed were held exactly between the two observations. Bowditch Ch. 7 §702 also notes the running fix is less accurate than a simultaneous fix.