USCG Exam PracticeEstimated position from current set & drift
A vessel departs a confirmed fix at 0800 steering 270° T at 6 knots. At 1000 the navigator plots the 1000 DR position. The predicted current has a set of 180° T and a drift of 1.5 knots. The navigator then constructs the 1000 EP. How far from the 1000 DR position is the EP, and in what direction?
- ✓ 3.0 NM in the direction 180° TCorrect
- B. 1.5 NM in the direction 000° T
- C. 3.0 NM in the direction 000° T
- D. 1.5 NM in the direction 180° T
Why A is correct
Bowditch Ch. 8 §803 directs the navigator to lay off the current's set and drift for the elapsed time from the DR position. Two hours have elapsed (0800–1000); drift is 1.5 kts, so the current displacement is 1.5 × 2 = 3.0 NM in the direction of set, which is 180° T. The EP lies 3.0 NM due south of the 1000 DR position.
Cited:Bowditch Ch. 8 §803