UK Nautical Miles
Abbreviation/Symbol:
UK NM
UK nmi
Unit of:
Worldwide use:
The UK Nautical Mile, also called the Admiralty nautical mile, is 6,080 feet. It has largely been replaced in navigation by the international nautical mile of 1,852 meters.
The UK Nautical Mile is exactly 1,853.184 meters (6,080 feet), which is 1.184 meters longer than the international nautical mile. Britain adopted the international one in 1970, so the Admiralty mile now belongs to older charts and books.
A UK nautical mile is 1.15152 statute miles, against 1.15078 for the international one. The difference is about 0.064%, or 1.184 meters in every nautical mile.
Definition:
The UK Nautical Mile, also called the Admiralty mile, is 6,080 feet, which is exactly 1,853.184 meters or 1.15152 statute miles. It was the British Admiralty's unit for measuring distance at sea.
The UK Nautical Mile is not derived from the international nautical mile, which is defined as 1,852 meters, roughly one minute of latitude along any meridian. It is the older Admiralty figure of 6,080 feet, so it is slightly longer than the international standard.
The older UK (Admiralty) nautical mile, 6,080 feet or 1,853.184m, was replaced in the UK by the international nautical mile of 1,852m in 1970.
Origin:
The UK nautical mile was fixed in the 19th century as the Admiralty mile, 6,080 feet, close to the length of a minute of latitude. Sailors had been judging distance in minutes of latitude long before that.
In the United Kingdom, the nautical mile was defined as one minute of latitude along any meridian. This definition was based on the fact that the Earth is approximately 21,600 nautical miles in circumference, and there are 60 minutes of latitude in a degree. Therefore, a nautical mile in the UK is equal to one-sixtieth of a degree of latitude.
On a sea chart you measure distance against the latitude scale down the side – a minute of latitude is a nautical mile, which is the whole point of the unit. Britain now uses the international 1,852m mile rather than its own.
Common references:
Shortest distance across the Atlantic ocean = 1390 UK nmi
Longest distance across the Atlantic ocean = 2590 UK nmi
Usage context:
Britain used the nautical mile for sea and air navigation until it adopted the international nautical mile of 1,852 meters (6,076.1 feet) in 1970. It is meant to be one minute of latitude, but that varies slightly, from 1,843 meters at the equator to 1,862 at the poles, because the Earth is not a sphere.
The UK nautical mile was 6,080 feet, which is 1,853.184 meters, a little longer than the international nautical mile of 1,852 meters. Speed at sea is given in knots, that is nautical miles per hour, in both.
International maritime law uses the international nautical mile of 1,852 meters, not the old UK one. For example, the territorial sea extends 12 nautical miles from the coast and an exclusive economic zone up to 200 nautical miles.