A nautical mile is equal to 1852 m. A nautical mile
Or adventures, in films about desperate sailors, in articles on geographical topics and in conversations between sailors, the term “nautical mile” often slips through. The time has come to figure out what length is equal to in shipping, and why sailors do not use the kilometers we are accustomed to.
What is 1 nautical mile?
Initially, this value corresponded to the length of 1/60 degree of the arc of a circle on the surface of the Earth with the center coinciding with the center of the planet. In other words, if we consider any meridian, then a nautical mile will be approximately equal to the length of one minute of latitude. Since it differs somewhat from the outline of an ideal sphere, the length of 1 minute of a degree of the meridian in question may differ slightly depending on latitude. This distance is greatest at the poles - 1861.6 m, and least at the equator - 1842.9 m. To avoid confusion, it was proposed to unify the length of the nautical mile. The length taken as a basis was 1 minute of degree at 45º latitude (1852.2 m). This definition led to the fact that the nautical mile became convenient for calculating navigation problems. For example, if you need to measure a distance of 20 miles on a map, then it will be enough to measure 20 arc minutes with a compass on any meridian marked on the map.
Beginning in 1954, the United States began using the international nautical mile (1852 m). In practice, it is often rounded to 1800 meters. An official designation for this unit was never adopted. Sometimes the abbreviation "nmi", "nm" or "NM" is used. By the way, “nm” is the generally accepted designation for nanometer. 1/10 international nautical mile = 1 cable = 185.2 meters. And 3 miles are equal to 1 nautical league. In the UK, their own nautical mile was often used, equal to 1853.184 m. In 1929, an international conference was held in Monaco on various issues of hydrography, at which the length of the nautical mile was determined to be 1852.00 meters. Do not forget that a mile can be not only sea, but also land. In this case, its length is 1.151 times less than sea length.
What is the relationship between a nautical mile and a knot?
The nautical mile, or, as it is sometimes called, geographical or navigational, has become widespread in geography, aviation and navigation. Closely related to it is the concept of a sea knot, used in shipping as the basic unit of speed. One knot is equal to one mile traveled per hour of the ship's movement. The name “knot” is due to the fact that in the old days a log was used on ships to measure speed. It was a log or board in the shape of a triangle to which a load was tied. A line (rope) was attached to this, on which knots were tied at a certain distance. The log was thrown overboard, after which, over a selected period of time (from 15 seconds to 1 minute), it was counted how many knots would go into the water.
There are different versions regarding the distance between nodes. Some believe that it was 25 feet and if one knot left in 15 seconds, the result was one nautical mile (100 feet/min). According to the second version, the knots were tied in 47 feet and 3 inches (14.4018 m), and the countdown took 28 seconds. In this case, one knot showed a speed of 101.25 ft/min.
We hope that now you will not have difficulty understanding maritime terminology, and miles with knots will become as understandable as regular kilometers.
Nautical mile
- the average arc length of one minute of the earth's meridian.
Arc length of one minute of the earth's meridian 1" = 1852.23 - 9.34 cos 2φ,
where φ is the latitude of the vessel in degrees.
The length of a nautical mile adopted in Russia is 1852.00 meters. Approximately 6080 feet.
Why 1852? If we take the shape of the Earth as a sphere, then the circumference along the meridian will be 40,000,000 meters. Hence 40,000,000 m: 360° = 40,000,000: 360*60" = 40,000,000: 21,600" = 1851, 85 meters in 1".
Example: distance to port 48 miles.
Or: 43 miles 8 cables. Or: 43.8 miles.
Cable
- one tenth of a nautical mile, rounded equal to 185 meters. 1 mile = 10 kbt.
Example:the distance to the ship is 14 cables.
Knot
- one nautical mile per hour (1.852 km/h) or 0.514 m/s (meters per second).
Example:ship speed 23 knots.
Knot is a linear speed of 1 nautical mile per hour. The term “knot” appeared in the era of sailing, when the speed of a ship was measured using the so-called sector lag - a sector-shaped wooden shield released from the stern of the ship into the water on a lagline (braided rope). Such a sector was held by laglin extensions at three points, due to which it maintained a perpendicular position in the water to the direction of the vessel's progress. Since the sector is slowed down by water, the lagline was etched approximately at the speed of the ship. If the laglin was divided into sections of 50.7 feet with the help of knots, that is, equal to 1\120 miles (6080\50.7 = 120), then at a speed of 1 knot the laglin will be etched in 1 minute or 1\60 hours by 1/60 miles (2 knots), and in 0.5 minutes - by 1 knot. If, for example, 9 knots were etched in 0.5 minutes, then it was considered that the ship was moving at a speed of 9 knots.
On English maps they are also used
MILE SEA
MILE SEA
(Nautical mile) - the length of 1\" of the meridian arc, considering the Earth to be a ball whose volume is equal to the volume of the earth's ellipsoid. Then the value of the nautical mile is determined from the equality:
n= 2π R/360·60 = R·arc 1\",
and according to the specified condition, where - semimajor axis of the earth's spheroid, b- minor axis.
If we take the values of these semi-axes according to the Clarke spheroid data, then n comes out to be 1853.3 m = 6080.4 ft. But in the USSR, all maps are built on the basis of Bessel spheroid data, therefore, by circular of the Hydrographic Administration No. 317 dated 8/VII 1931, the value of the nautical mile was set at 1852.0 m, which corresponds to the length of 1\" arc of the elliptical meridian at latitude 45°, i.e. the value:
(a + b)/2 arc1\"
according to Bessel spheroid data.
If we take 1" arc of the elliptical meridian as a unit for measuring distances, then the divisions of the vertical frames of the map will represent this scale. This value changes with the latitude of the place from 1842.7 m= 6045.7 feet at equator to 1861.3 m= 6106.7 feet at the poles. Difference 18.6 m, component of 1% lies outside the accuracy of measuring lag distances.
Our standard nautical mile is 1852.0 m = 6076.1 feet is used to calibrate the log scale and for various calculations.
The British consider a nautical mile to be equal to 6080 feet. and call it "Admiralty knot".
They call the length of 1" of the earth's elliptical meridian, i.e., a value that varies with latitude, "Nautical mile" or "Sea mile".
In other countries where other values are adopted for the semi-axes of the ellipsoid And b or where the radius of an imaginary globe, replacing the earth's ellipsoid, is determined not from a comparison of volumes, but by other methods, for example. By comparing the surfaces, there and for the nautical mile we obtain values that are slightly different from 6080 feet, but close to them. The table below shows the nautical mile lengths adopted in various countries.
States | Nautical mile length |
|
Germany | ||
Holland | ||
Portugal | ||
Samoilov K. I. Marine Dictionary. - M.-L.: State Naval Publishing House of the NKVMF of the USSR, 1941
nautical mile
a unit for measuring distances at sea, equal to the arc length of the earth's meridian in 1'. In different countries, the mile is defined at different latitudes, so it has different meanings. In Russia, a nautical mile is taken at latitude 44°30’ and is 1852 m, in the UK and Japan - 1853.18 m, in the USA - 1853.24 m, in Italy - 1851.85 m. The international nautical mile is 1852 m.
EdwART. Explanatory Naval Dictionary, 2010
Mile Morskaya
naval unit of length used for measurements at sea, equal to 1852 m. The old Russian mile was equal to 7.468 m.
EdwART. Marine Dictionary, 2010
See what "SEA MILE" is in other dictionaries:
Nautical mile, a unit of measurement of distances at sea. Defined as the length of one minute of the arc of the Earth's circumference. The international nautical mile is 1852 m (6076.04 ft), in the UK the nautical mile is 6080 ft (1853.18 m). Speed equal to 1... ... Scientific and technical encyclopedic dictionary
1 nautical mile is equal to 1852 m Dictionary of business terms. Akademik.ru. 2001... Dictionary of business terms
nautical mile- a unit for measuring distances at sea, equal to the arc length of the earth's meridian in 1. An international nautical mile is 1852 m... Marine Biographical Dictionary
nautical mile- A Nautical MILE is equal to the length of one terrestrial minute. meridian For the first time the magnitude of the sea. M. b. established in France in 1880, and the length of 1/4 of the circle of Paris was used to calculate it. meridian, to paradise after a whole series of measurements b. defined in… … Military encyclopedia
Every schoolchild knows perfectly well that a nautical mile is a unit of measurement that calculates distance over large expanses of water. Nowadays, this quantity is not included in the international system of physical units, but it is widely used by almost all nations, both European and American. That is why in different sources you can find different designations for this indicator. Among these are NM, nmi and others.
The history of the nautical mile
The nautical mile appeared around the Renaissance. Then the sailors calculated the distances that they had to sail on ships, based on the characteristics of the arcs of the earth's meridians. So this naval unit of distance measurement was equal to the length of one degree of the meridian arc, and was calculated using a complex mathematical formula. However, due to the fact that our planet had and still has the shape of an ellipse, this arc minute in practice was not a constant value. Since the radius of curvature in certain latitudes of the ellipsoid is different, such a value as a nautical mile would be smallest near the equator and largest at the Earth’s poles.
Final adoption of this metric unit
In this regard, in the twentieth century, in particular in the USSR, the average standard unit of measurement of distance in the sea was adopted. The formula by which this value was calculated was based on an angle of 45 degrees, and the result was a number equal to 1852 meters. Despite the fact that the nautical mile can be converted into units of measurement so familiar to us, it is not used as a metric measure. Since it is based on one degree of arc of the meridian of our planet, it becomes an angular unit of measurement. In matters related to shipping, especially over fairly long distances, this is very convenient and acceptable.
Mathematical division of one mile
As we can see, a nautical mile in total is almost two kilometers. In some cases, this value is too large for sea travel. That is why this value was divided into cables. There are 10 cables in one mile, which in turn is equal to one-third of a naval league. This value is not used in shipping and other sciences, but sometimes it serves as a guideline that allows you to make more accurate calculations and lay out a more detailed and correct sea route.
What other miles are there?
Knowing the features of American units of measurement, many people are confused about what 1 nautical mile is equal to. In this country, this measure is used not only in shipping, but also overland distances. One US mile, which is often used to indicate the speed of a car and the distance it travels, is equal to 1609.344 meters. It is also worth noting that in this country, in some cases, there are differences in maritime units of measurement of lengths. Thus, a nautical mile in the states in some documents is equal to 1853.249 meters. However, if it is necessary to export cargo according to documents concluded with the countries of Europe and Asia, then the international measurement system is used, which was recognized as official in 1929.
Speed equal to one nautical mile (1852 m) per hour
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Non-systemic tradition. naval speed unit, 1 nautical mile per hour or 1.852 km/h, 0.5144 m/s
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A unit of ship speed equal to one nautical mile per hour
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Place of articulation of various parts of the bow
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The place where the ends of ropes and threads are tied
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A point at the intersection of several lines, a connection between branches of an electrical circuit, a junction of reinforcement bars, etc.
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Functionally related structures, premises, equipment
Part of a mechanism or technical device that is a complex connection of parts
Part of a mechanism, installation, etc., consisting of several parts
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Unit of speed (marine)
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Story by Russian writer M. Zoshchenko
Unit of speed (marine)
Gordian plot
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Vessel speed
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Marine cable fastening
. Sailor's leg of lamb
Jacket on a rope
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Complex connection of parts
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Shoelace tying and boat speed
Ship speed unit
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Place where laces are tied
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A measure of the speed of a ship
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Lymphatic "tie"
. "Gordian" measure of ship speed
What did the Macedonian cut down?
Rope confusion
Tangle of ropes
A sheet instead of a suitcase for travel
Assembly unit
vertex of the graph
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Weaving Gordia
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Unit part
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A unit of ship speed equal to one nautical mile per hour
A measure of the speed of ships
A place where the ends of something are tightly connected
Part of the mechanism
