Chart Navigation & Plotting · Speed-Time-Distance — Three-Minute Rule
You travel 0.6 nautical miles in 3 minutes. Using the three-minute rule, what is your speed?
- A6 knots
- B12 knots✓ Correct
- C18 knots
- D20 knots
Explanation
The three-minute rule: distance in yards in 3 minutes ÷ 100 = speed in knots, equivalently speed (kn) = distance (nm in 3 min) × 20. 0.6 nm × 20 = 12 knots.
Authority: Bowditch (Pub. No. 9), speed-time-distance; three-minute rule
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