Chart Navigation & Plotting · Set & Drift — Computing Current
Your 1200 DR position is 3.0 nm due north (000°T) of your simultaneous 1200 fix. The elapsed time since your last fix was 1 hour. What is the set and drift of the current?
- ASet 090°T, drift 3.0 knots
- BSet 000°T, drift 3.0 knots
- CSet 180°T, drift 1.5 knots
- DSet 180°T, drift 3.0 knots✓ Correct
Explanation
The current vector runs from the DR position toward the fix. The fix is south of the DR, so the set (direction toward which the current flows) is 180°T. Drift = distance ÷ time = 3.0 nm ÷ 1 h = 3.0 knots.
Authority: Bowditch (Pub. No. 9), determining set and drift
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