Chart Navigation & Plotting · Set & Drift — Course to Steer
You wish to make good a course of 090°T. The current sets 180°T at 2.0 knots and your speed through the water is 10 knots. Approximately what course must you steer?
- A101°T
- B079°T✓ Correct
- C090°T
- D068°T
Explanation
The southerly current (180°) pushes you right of the desired 090° track, so you must steer left (toward north). sin(offset) = 2 ÷ 10 = 0.20, offset ≈ 11.5°. Steering 090° − 11.5° ≈ 079°T heads up-current to make good due east.
Authority: Bowditch (Pub. No. 9), current sailing; set and drift vector triangle
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