Speed, Distance, and Time
Speed at sea is measured in knots — one knot equals one nautical mile per hour. Distance is measured in nautical miles (M or nm). One nautical mile = 1,852 metres = 1 minute of latitude.
The speed-distance-time triangle: Speed = Distance ÷ Time, Distance = Speed × Time, Time = Distance ÷ Speed. If you are travelling at 5 knots and need to cover 15 nautical miles, it will take 15 ÷ 5 = 3 hours.
Key Points
- 1 knot = 1 nautical mile per hour
- 1 nautical mile = 1,852 metres = 1 minute of latitude
- S = D ÷ T, D = S × T, T = D ÷ S
- Measure distance using dividers on the latitude scale