Kilometers per hour (kph) to knots

 

 

A knot is a linear speed of 1 nautical mile per hour. The term "knot" appeared in the era of sailing, when the speed of a vessel was measured using the so-called sector log - a wooden sector-shaped shield released from the stern of the vessel into the water on a logline (braided rope). The logline's branches held such a sector at three points, so it maintained a perpendicular position in the water to the direction of the vessel's movement. Since the sector is slowed by water, the logline was floated out approximately at the vessel's speed. If the logline was divided into sections of 50.7 feet using knots, i.e., equal to 1120 miles (608050.7=120), then at a speed of 1 knot, the logline will float out 160 miles (2 knots) in 1 minute or 160 hours, and 1 knot in 0.5 minutes. If, for example, 9 knots were dropped in 0.5 minutes, then the ship was considered to be moving at a speed of 9 knots.

English maps also use feet (0.3048 m) and fathoms - 1.83 m. The log determines the distances traveled by a ship and its speed.