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20-557: (Redirected from L-12 ) L12 may refer to: Ships and boats [ edit ] HMS  L12 , a submarine of the Royal Navy HMS ; Albrighton  (L12) , a destroyer of the Royal Navy HMS  Ocean  (L12) , a helicopter carrier of the Royal Navy HMS  Sandwich  (L12) , a sloop of the Royal Navy Soviet submarine  L-12 ,

40-572: A Leninets-class submarine Other uses [ edit ] Lectionary 12 , a 12th-century, Greek manuscript of the New Testament Liberty L-12 , an American aircraft engine Lockheed L-12 Electra Junior , an American passenger aircraft LSWR L12 class , a class of steam locomotives TEDOM L 12 , a Czech bus L-12, an L-class blimp of the United States Navy [REDACTED] Topics referred to by

60-599: 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 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

80-588: 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,

100-406: 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

120-549: A length of 238 feet 7 inches (72.7 m) overall , a beam of 23 feet 6 inches (7.2 m) and a mean draft of 13 feet 3 inches (4.0 m). They displaced 914 long tons (929 t) on the surface and 1,089 long tons (1,106 t) submerged. The L-class submarines had a crew of 38 officers and ratings . For surface running, the boats were powered by two 12-cylinder Vickers 1,200- brake-horsepower (895 kW) diesel engines , each driving one propeller shaft . When submerged each propeller

140-579: 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

160-515: Is different from Wikidata All article disambiguation pages All disambiguation pages HMS L12 HMS L12 was a L-class submarine built for the Royal Navy during World War I. She was one of five boats in the class to be fitted as a minelayer . The boat survived the war and was sold for scrap in 1932. L9 and its successors were enlarged to accommodate 21-inch (53.3 cm) torpedoes and more fuel. The submarine had

180-467: The 21-inch tubes for a grand total of ten torpedoes of all sizes. They were also armed with a 4-inch (102 mm) deck gun . L12 was fitted with 16 vertical mine chutes in her saddle tanks and carried one mine per chute. HMS L12 was built by Vickers , Barrow-in-Furness . She was laid down on 22 January 1917 and was commissioned on 30 June 1918. The boat collided with the submarine HMS  H47 off Milford Haven , Wales on 9 July 1929. She

200-504: 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

220-480: The equator forms 500 stadia , which make 62 ⁠ 1 / 2 ⁠ miles"). Whether a correction or convenience, 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

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240-572: 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

260-679: The late 16th century English geographers and navigators knew that the ratio of distances at sea to degrees 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

280-430: 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

300-403: 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

320-448: The same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. 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=L12&oldid=1090384630 " Category : Letter–number combination disambiguation pages Hidden categories: Short description

340-533: Was able to surface and returned to Milford Haven ; three sailors died. HMS L12 was sold to John Cashmore Ltd on 16 February 1932 for scrapping at Newport . Nautical mile There is no single internationally agreed symbol, with several symbols in use. The word mile 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

360-491: Was driven by a 600-horsepower (447 kW) electric motor . They could reach 17 knots (31 km/h; 20 mph) on the surface and 10.5 knots (19.4 km/h; 12.1 mph) underwater. On the surface, the L class had a range of 3,800 nautical miles (7,000 km; 4,400 mi) at 10 knots (19 km/h; 12 mph). The boats were armed with four 21-inch torpedo tubes in the bow and two 18-inch (45 cm) in broadside mounts. They carried four reload torpedoes for

380-491: 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 –

400-453: 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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