Chart Navigation & Plotting · Set & Drift — Drift Calculation
Six hours after your last fix, your fix falls 9.0 NM from your DR for the same time. What is the drift of the current?
- A3.0 knots
- B0.67 knots
- C1.5 knots✓ Correct
- D9.0 knots
Explanation
Drift = distance between DR and fix divided by time since the DR was last reset to a fix: 9.0 NM ÷ 6 h = 1.5 knots.
Authority: Bowditch (Pub. No. 9), Current Sailing
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