USCG Exam PracticePlot true course and distance between two charted points
A vessel is steaming on a steady course and speed. The navigator has not obtained a new fix. According to dead reckoning procedure, at a minimum, how frequently must a new DR position be plotted, and what additional events require an immediate new DR position?
- A. Every two hours; a new DR is required only at course changes
- B. Every 30 minutes; a new DR is required at speed changes only
- ✓ At least once each hour; a new DR is also required at every course change, speed change, and at the time of each fixCorrect
- D. At least once each hour; a new DR is required only when the vessel enters pilot waters
Why C is correct
A new DR position must be plotted at every course change, at every speed change, at the time of each fix, and at least once each hour — more often in pilot waters. All four triggering conditions are required, not just one.
Cited:Bowditch Ch. 8 §801