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A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. [2] [3] [4] Historically, it was defined as the meridian arc length corresponding to one minute ( 1 / 60 of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees).
Although the unit knot does not fit within the SI system, its retention for nautical and aviation use is important because the length of a nautical mile, upon which the knot is based, is closely related to the longitude/latitude geographic coordinate system. As a result, nautical miles and knots are convenient units to use when navigating an ...
Knot: Speed: League: Length: Nautical mile: Length: Rhumb: Angle: The angle between two successive points of the thirty-two point compass (11 degrees 15 minutes) (rare) [1] Shackle: Length: Before 1949, 12.5 fathoms; later 15 fathoms. [2] Toise: Length: Toise was also used for measures of area and volume Twenty-foot equivalent unit or TEU: Volume
As one degree is 1 / 360 of a circle, one minute of arc is 1 / 21600 of a circle – such that the polar circumference of the Earth would be exactly 21,600 miles. Gunter used Snellius's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude. [24]
With the introduction of the nautical mile as a standard unit of measure at sea in the 15th century, they began to mark the line at equal intervals proportional to the nautical mile and to the time interval used for measurement. Initially, the markings were simply knots in the line. Later, sailors worked knotted cords into the log-line.
The nautical mile per hour is known as the knot. Nautical miles and knots are almost universally used for aeronautical and maritime navigation, because of their relationship with degrees and minutes of latitude and the convenience of using the latitude scale on a map for distance measuring.
Nautical mile record is held by Paul Larsen. On 18 November 2012 he sailed the Vestas Sailrocket 2 at 55.32 knots in Walvis Bay, Namibia. [2] 24 Hour distance record is held by Pascal Bidégorry. On 1 August 2009 he sailed the Banque Populaire V 908 nautical miles (at 37.84 knots).
nautical mile: nmi nmi the international standard nautical mile 1.0 nmi (1.9 km; 1.2 mi) nautical mile: oldUKnmi (admiralty nmi) nmi 6080 ft the pre-1970 British nautical mile: 1.0 nmi (1.9 km; 1.2 mi) Brnmi (Brit) nmi admi nmi (admiralty) nautical mile: oldUSnmi nmi 6080.2 ft the pre-1954 US nautical mile 1.0 nmi (1.9 km; 1.2 mi) pre1954USnmi