A nautical mile is a unit of length used in air, marine, and space navigation , and for the definition of territorial waters . 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). Today the international nautical mile is defined as 1,852 metres (about 6,076 ft; 1.151 mi). The derived unit of speed is the knot , one nautical mile per hour.
22-481: [REDACTED] Look up astute in Wiktionary, the free dictionary. Astute may refer to: HMS Astute (P447) , launched 1945, Amphion -class submarine (United Kingdom), scrapped 1970 HMS Astute (S119) , launched 2007, nuclear-powered attack submarine (United Kingdom) Astute -class submarine , a class of which HMS Astute (S119)
44-588: A quarter meridian . So 10,000,000 m / 90 × 60 = 1,851.85 m ≈ 1,852 m became the metric length for a nautical mile. France made it legal for the French Navy in 1906, and many metric countries voted to sanction it for international use at the 1929 International Hydrographic Conference. Both the United States and the United Kingdom used an average arcminute—specifically,
66-406: A degree (5866 2 / 3 feet per arcminute ). In 1633, William Oughtred suggested 349,800 feet to a degree (5830 feet per arcminute). Both Gunter and Oughtred put forward the notion of dividing a degree into 100 parts, but their proposal was generally ignored by navigators. The ratio of 60 miles, or 20 leagues, to a degree of latitude remained fixed while the length of the mile
88-530: A maximum of 219 tonnes (241 short tons) of diesel fuel , although it usually carried between 159 and 165 tonnes (175 and 182 short tons). The submarine had a maximum surface speed of 18.5 knots (34.3 km/h; 21.3 mph) and a submerged speed of 8 knots (15 km/h; 9.2 mph). When submerged, it could operate at 3 knots (5.6 km/h; 3.5 mph) for 90 nautical miles (170 km; 100 mi) or at 8 knots (15 km/h; 9.2 mph) for 16 nautical miles (30 km; 18 mi). When surfaced, it
110-579: A minute of arc of a great circle of a sphere having the same surface area as the Clarke 1866 ellipsoid . The authalic (equal area) radius of the Clarke 1866 ellipsoid is 6,370,997.2 metres (20,902,222 ft). The resulting arcminute is 1,853.2480 metres (6,080.210 ft). The United States chose five significant digits for its nautical mile, 6,080.2 feet , whereas the United Kingdom chose four significant digits for its Admiralty mile, 6,080 feet. In 1929
132-498: Is from the Latin phrase for a thousand paces: mille passus . Navigation at sea was done by eye until around 1500 when navigational instruments were developed and cartographers began using a coordinate system with parallels of latitude and meridians of longitude . The earliest reference of 60 miles to a degree is a map by Nicolaus Germanus in a 1482 edition of Ptolemy 's Geography indicating one degree of longitude at
154-421: Is the lead ship USS Astute (AM-148) , US Navy minesweeper Operation Astute , an Australian military operation in response to the 2006 East Timor crisis See also [ edit ] All pages with titles beginning with Astute All pages with titles containing Astute Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
176-545: The bow and stern, and it could carry twenty torpedoes . Its complement was sixty-one crew members. Astute was laid down at Vickers-Armstrongs Barrow-in-Furness shipyard on 4 April 1944, was launched on 30 January 1945 and completed on 30 June 1945. Astute arrived at Halifax, Nova Scotia on 11 April 1950 for a six-week training period with the Royal Canadian Navy ending on 1 July. Astute spent 21 months in 1955–56 based at Halifax as part of
198-883: The Canadian submarine squadron, leaving Canada for the UK on 10 December 1956. As a response to the Cuban Missile Crisis , Astute and sister ship Alderney , both part of the Halifax-based 6th Submarine Squadron, were deployed to the North-East of the Grand Banks to warn if Soviet submarines were to be sent across the Atlantic to Cuba. Nautical mile There is no single internationally agreed symbol, with several symbols in use. The word mile
220-469: The Equator contains " milaria 60 ". An earlier manuscript map by Nicolaus Germanus in a previous edition of Geography states " unul gradul log. et latitud sub equinortiali formet stadia 500 que fanut miliaria 62 1 / 2 " ("one degree longitude and latitude under the equator forms 500 stadia , which make 62 1 / 2 miles"). Whether a correction or convenience,
242-504: The distance along a great circle was 60 miles per degree. However, these referred to the old English mile of 5000 feet and league of 15,000 feet, relying upon Ptolemy's underestimate of the Earth's circumference . In the early seventeenth century, English geographers started to acknowledge the discrepancy between the angular measurement of a degree of latitude and the linear measurement of miles. In 1624 Edmund Gunter suggested 352,000 feet to
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#1732772848976264-572: The international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1,852 metres (which is 6,076.12 ft). The United States did not adopt the international nautical mile until 1954. Britain adopted it in 1970, but legal references to the obsolete unit are now converted to 1,853 metres (which is 6,079.40 ft). The metre
286-430: The measurement based on this ( 40,075.017 km / 360 × 60 = 1,855.3 metres) is known as the geographical mile . Using the definition 1 / 60 of a degree of latitude on Mars , a Martian nautical mile equals to 983 m (1,075 yd). This is potentially useful for celestial navigation on a human mission to the planet , both as a shorthand and a quick way to roughly determine
308-403: The poles and 1,843 metres at the Equator. France and other metric countries state that in principle a nautical mile is an arcminute of a meridian at a latitude of 45°, but that is a modern justification for a more mundane calculation that was developed a century earlier. By the mid-19th century, France had defined a nautical mile via the original 1791 definition of the metre , one ten-millionth of
330-467: The reason for the change from 62 1 / 2 to 60 miles to a degree is not explained. Eventually, the ratio of 60 miles to a degree appeared in English in a 1555 translation of Pietro Martire d'Anghiera 's Decades: "[Ptolemy] assigned likewise to every degree three score miles." By the late 16th century English geographers and navigators knew that the ratio of distances at sea to degrees
352-525: The surface and 1,590 tonnes (1,750 short tons) while submerged. It had a total length of 293 feet 6 inches (89.46 m), a beam length of 22 feet 4 inches (6.81 m), and a draught length of 18 feet 1 inch (5.51 m). The submarine was powered by two Admiralty ML eight-cylinder diesel engines generating a power of 2,150 horsepower (1,600 kW) each. It also contained four electric motors each producing 625 horsepower (466 kW) that drove two shafts . It could carry
374-469: The title Astute . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Astute&oldid=1076497487 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages HMS Astute (P447) HMS Astute (P447)
396-423: Was able to travel 15,200 nautical miles (28,200 km; 17,500 mi) at 10 knots (19 km/h; 12 mph) or 10,500 nautical miles (19,400 km; 12,100 mi) at 11 knots (20 km/h; 13 mph). Astute was fitted with ten 21-inch (533 mm) torpedo tubes , one QF 4-inch naval gun Mk XXIII , one Oerlikon 20 mm cannon , and a .303 British Vickers machine gun . Its torpedo tubes were fitted to
418-550: Was an Amphion -class submarine . Her keel was laid down by Vickers at Barrow-in-Furness . She was launched in 1944 and commissioned in 1945. In 1953 she took part in the Fleet Review to celebrate the Coronation of Queen Elizabeth II . Astute was scrapped on 1 October 1970 at Dunston on Tyne . Like all Amphion -class submarines, Astute had a displacement of 1,360 tonnes (1,500 short tons) when at
440-571: Was constant along any great circle (such as the equator , or any meridian), assuming that Earth was a sphere. In 1574, William Bourne stated in A Regiment for the Sea the "rule to raise a degree" practised by navigators: "But as I take it, we in England should allowe 60 myles to one degrée: that is, after 3 miles to one of our Englishe leagues, wherefore 20 of oure English leagues shoulde answere to one degrée." Likewise, Robert Hues wrote in 1594 that
462-491: Was originally defined as 1 ⁄ 10,000,000 of the length of the meridian arc from the North pole to the equator (1% of a centesimal degree of latitude), thus one kilometre of distance corresponds to one centigrad (also known as centesimal arc minute) of latitude. The Earth's circumference is therefore approximately 40,000 km. The equatorial circumference is slightly longer than the polar circumference –
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#1732772848976484-453: Was revised with better estimates of the earth’s circumference. In 1637, Robert Norwood proposed a new measurement of 6120 feet for an arcminute of latitude, which was within 44 feet of the currently accepted value for a nautical mile. Since the Earth is not a perfect sphere but is an oblate spheroid with slightly flattened poles, a minute of latitude is not constant, but about 1,862 metres at
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