USCG Exam PracticeEstimated position from current set & drift
A navigator wishes to make good a track of 090° T despite a current with set 000° T and drift 2 knots. Using the vector triangle from Bowditch, which procedure correctly determines the required course to steer?
- A. Add the drift speed to the vessel's speed and steer 090° T
- ✓ From the desired course-made-good vector and the current vector, solve for the course-steered vector that, when added to the current vector, yields the 090° T trackCorrect
- C. Steer 090° T and apply a leeway correction equal to the drift
- D. Plot the set vector from the last fix and steer parallel to the resulting line
Why B is correct
Bowditch Ch. 24 §2402 states that the vector triangle can be inverted: from the desired course made good and the known drift vector, derive the course to steer. The navigator constructs the triangle so that course steered plus current vector equals the desired 090° T track, then measures the required course steered from the chart.
Cited:Bowditch Ch. 24 §2402