1 sea mile (Nautical Mile) be equal to 1.852 kilometre (Kilometre) or 1.15 miles (Mile) . The earliest " sea mile " the cost is not fixed, the latitudinal change that goes up with meridian in nautical graph comes magnanimity, but the earth is not standard sphere, 1 degree distance is not identical. International aqueduct was measured 1929 announce on the conference, the 1 sea mile of international standard is equal to latitude 44 ° are meridian length of 1 minute. The United States decided to use this one international 1954 current level, england just used this level 1972.
Graph, from go up under for 1 mile of 1 kilometer, contrast with 1 sea mile
It is early before 1800, appeared sea mile is mixed li of case (the unit of length of maritime range finding that 200~300 uses before New Year, 1 li of case are equal to 3 sea mile) . 1.828 kilometre are equal to in 1 sea at first, as scientific progress people discovers the earth is not body of a pellet, however polar slightly flat ellipse is spherical body. Be in so of different latitude child midday encircles 1 minute of arc length not to agree, sea mile is the longest on equator, 1 sea mile is 1.961 kilometre.
We see the meeting in the sea changes as latitudinal change, if use this kind of technics, can cause a lot of disorders. Before uniting a standard, everybody eachs does things in his own way. England 48 ° distance of 1 minute is 05 ′ latitudinal line surely 1 England sea mile, its value is 1.853 kilometre.
Still have in addition " equatorial sea mile " and " geographical sea mile " view, former the length that is earthly equator 1 minute, 1 sea mile approximates 1.855 kilometre. Latter considers the world to be pellet body, ° of will equatorial 1/15 serves as 1 sea mile, its value is 7420 meters. Sea mile is not equal in Yu Ying, both the ratio between is 38:31. Normally the meeting in course uses sea mile unit, spaceflight, aviation can use mile of unit. When the speed of computational shipping travelling speed or tide, can use normally " section " (Knot) will express (be equal to 1 sea mile 1 times) .
