What is a nautical mile and what is a nautical knot?

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2019-04-02 19:20:21

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In books about sea travel or adventure, films about desperate sailors, in articles on geographical topic in the conversation between the sailors often slips the term "nautical mile". It's time to figure out what is this measure of length in navigation, and why sailors don't use our usual miles.

What is 1 nautical mile?

what is 1 nautical mileInitially, this value corresponds to the length of 1/60 of a degree arc of the circle on the Earth's surface with center coincident with the center of the planet. In other words, if we consider any Meridian, the nautical mile is the Is approximately equal to the length of one minute of latitude. Since the shape of the Earth differs slightly from the shape of an ideal ball, the length of 1 minute of a degree of the Meridian in question may vary somewhat depending on the latitude. Most of this distance on the pole – 1861,6 m, and less at the equator – 1842,9 m. to avoid confusion, it was proposed to unify the length of the nautical mile. The basis was adopted length of 1 minute of a degree at 45º latitude (1852,2 m.). Such a definition has led to the fact that the nautical mile has become convenient to calculate the navigation task. For example, if you want the map to measure distance in 20 miles, it will be enough to measure the compass of 20 minutes of arc on any Meridian, marked on the map. 
nautical mile

Since 1954, the United States began to use the international nautical mile (1852 m). In practice it is often rounded up to 1800 meters. The official designation of this unit has not been taken. Sometimes there is a reduction of "nmi", "nm" or "NM". By the way, "nm" is a common designation of a nanometer. 1/10 international nautical mile = 1 cable length = 185,2 meters. 3 miles equals 1 nautical League. In the UK had often used its nautical mile, equal 1853,184 M. In 1929 in Monaco hosted an international conference devoted to various aspects of hydrography, where the length of the nautical mile was defined in 1852,00 meters. Don't forget that mil is not only sea but also land. In this case, its length in 1,151 times less than the sea.

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What is the connection between nautical mile and a knot?

nautical mileSea Mile (nautical mile) or as it is sometimes called geographic or navigation, is widespread in the geography of aviation and navigation. Since it is closely related to the concept of Maritime knot that is used in navigation as the main unit of speed. One node passed equal to one mile per hour movement of the vessel. The name “node” due to the fact that in the old on ships to measure speed used lag. It was a log or Board in the form of a triangle, to which were attached the cargo. To such floating anchor tied the tench (rope), which after some distance was tied up knots. The lag was discharged overboard, after which for a selected period of time (from 15 seconds to 1 minute) counts how many nodes will go into the water.

There are different versions regarding the distance between nodes. Some believe that it was 25 feet (7.62 m), and if with 15 left one node, then the result is one nautical mile (100 ft/min). According to the second version, knots tied through 47 feet and 3 inches (14,4018 m), and the countdown was for 28 seconds. In this case, one node showed the speed 101,25 feet/min.

Hopefully, now you will not have difficulty in understanding marine terminology, and miles with the nodes will be as clear as usual kilometers.


Article in other languages:

AR: https://tostpost.com/ar/education/16205-what-is-a-nautical-mile-and-what-is-a-nautical-knot.html

BE: https://tostpost.com/be/adukacyya/31485-shto-takoe-marskaya-m-lya-chamu-ro-ny-marsk-vuzel.html

DE: https://tostpost.com/de/bildung/31165-was-ist-der-nautische-meile-und-was-ist-maritime-knoten.html

ES: https://tostpost.com/es/la-educaci-n/31027-qu-es-la-milla-y-a-que-es-igual-la-marina-sitio.html

HI: https://tostpost.com/hi/education/17831-what-is-a-nautical-mile-and-what-is-a-nautical-knot.html

JA: https://tostpost.com/ja/education/15876-what-is-a-nautical-mile-and-what-is-a-nautical-knot.html

KK: https://tostpost.com/kk/b-l-m/31807-b-l-te-z-milya-zh-ne-nege-te-te-z-toraby.html

PL: https://tostpost.com/pl/edukacja/32879-co-to-jest-mila-i-ile-wynosi-morskiej-w-ze.html

PT: https://tostpost.com/pt/educa-o/32602-o-que-a-milha-mar-tima-e-que-igual-a-marinha-site.html

TR: https://tostpost.com/tr/e-itim/28214-nedir-deniz-mili-ve-neye-e-ittir-deniz-d-m.html

UK: https://tostpost.com/uk/osv-ta/32024-scho-take-mors-ka-milya-chomu-dor-vnyu-mors-kiy-vuzol.html

ZH: https://tostpost.com/zh/education/6010-what-is-a-nautical-mile-and-what-is-a-nautical-knot.html






Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."

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