Nautical Mile per Hour

A nautical mile per hour is one knot, the standard unit of speed at sea. The international nautical mile was fixed at exactly 1,852 meters by the First International Extraordinary Hydrographic Conference in 1929 (the United States adopting it in 1954), approximating one minute of latitude. So one knot equals 1,852 meters per hour, about 1.151 statute miles per hour or 0.5144 meters per second. The term knot comes from the knotted log line once streamed astern and timed against a sandglass to read a ship’s speed.