USCG Exam PracticeDanger bearings and danger circles
A danger circle is scribed on the chart around a submerged rock at a radius equal to the desired safe passing distance. The danger bearing is then drawn from a charted lighthouse tangent to this circle. What is the purpose of using the danger circle rather than the rock itself?
- A. To account for compass deviation when observing the lighthouse
- ✓ To establish a safe clearance margin beyond the charted edge of the hazardCorrect
- C. To convert the danger bearing into a line of position for fixing purposes
- D. To allow the danger bearing to be used as a running fix advance line
Why B is correct
Bowditch Ch. 7 §706 specifies that the line may be drawn tangent to a danger circle scribed at a safe distance around the hazard, not merely to its charted edge. This builds a clearance margin into the danger bearing so the vessel does not pass too close even when navigating exactly on the bearing line.
Cited:Bowditch Ch. 7 §706