18 nautical knots how many kilometers per hour. Determination of ship speed in knots and conversion to kilometers per hour. Why is speed measured in knots at sea?

And speed. Units of measurement can be difficult to understand for non-marine people, so determining distances and speeds of ships can present some difficulties. The main unit of speed used at sea is the knot. What it is equal to and how to calculate speed using it will be discussed in the article.

Nautical mile

At sea, the main measure of distance is the mile. It is important to note that a sea mile and a land mile are different things. The land length is 1609 meters. A nautical mile is equal to the length of one minute of the earth's meridian line. The Earth's meridian is conventionally an arc, and its length is measured in degrees, minutes and seconds. Thus, the length of one nautical mile is 1852 meters. The difference between a land mile and a nautical mile is significant, so it is important not to confuse these units of measurement.

In addition to the mile, distance at sea is measured using units such as feet, inches, yards, fathoms and sea cables.

Sea knot: ship speed

Having dealt with distance at sea, we need to turn to the concept of speed. To determine speed at sea, the concept is used - the unit of speed with which a ship will travel one nautical mile in an hour. How many km are there in a maritime hub? It turns out that one sea knot is 1.852 km per hour. Thus, 10 sea knots is 18.5 km per hour, 100 sea knots is 185 km per hour, and so on.

Example of calculating ship speed

The ship is moving at a speed of 20 nautical knots. He needs to cover a distance of 100 km to his destination. What is his speed in kilometers, and how long will it take him to cover this distance?

First you need to convert the speed from knots to kilometers; to do this, 20 needs to be multiplied by 1.852. It turns out that the speed of the ship in kilometers is 37 km per hour.

Then divide the distance of 100 km by the ship's speed of 37 km/h. It turns out that the ship will take approximately 2.7 hours to reach its destination, traveling at a speed of 20 nautical knots.

Vessel speeds depend on their size, technical characteristics, purpose and other factors. and passenger liners usually travel at a speed of 10-20 knots, and military ships are capable of much higher rates of movement. For example, the HCMS Bras D"Or 400 warship has a speed of 62 knots (116 km per hour).

Origin of the term "maritime knot"

Shipping is one of the oldest human activities. It is obvious that in ancient times there were no compasses, locators, navigators and other technical achievements of later times. However, sailors needed to look for some landmarks in order to determine their location. They navigated by the stars, the moon, lighthouses, the outlines of coastal relief, and so on.

A special invention was used to determine the distance traveled. It was called a log and was a log with a rope tied to it. Knots were tied on the rope at equal distances from each other. The log was thrown from the stern of the ship. When the rope was stretched, the sailor counted the number of knots passed through his hands during the movement of the ship.

This is how the tradition of measuring speed with sea knots was established, although the modern knot has a different size than in ancient times. In modern navigation, the log is still used to measure the speed of the ship. It looks, of course, different than in the past, and is a special device.

So, at sea, the calculation of speed in sea knots has been carried out since ancient times. A knot corresponds to the speed at which a ship will travel one nautical mile in an hour. To convert speed in knots to speed in kilometers, multiply the knots by 1.852 (the length of one nautical mile).

In our life, the speed of vehicles is measured in kilometers per hour (km/h). This is how the movement of a car, train, or plane is characterized. But there is one exception to this rule. In maritime navigation, the speed of a ship is indicated in knots. This unit of measurement is not included in the International SI System, but is traditionally accepted for use in navigation.

Vessel speed measurement

This order has developed historically. Once upon a time, the speed of a ship's movement was determined using a special device called sector log. It was a board, at the end of which a line was attached - a thin ship's cable. Knots were tied at regular intervals along its entire length. The sailor, touching the cable with his hand, counted the number of knots that passed through his hand in a certain time, thus determining the speed immediately in knots. It is important that this method did not require any additional calculations.

No one has been using lags of this design for a long time. Nowadays, instruments based on the latest scientific and technical achievements in the field of hydroacoustics and hydrodynamics are used to measure the speed of sea vessels. Meters based on the Doppler effect are popular. There are simpler methods - using special metal turntables placed in water. In this case, the speed is determined based on the number of revolutions per unit time.

Nautical mile

Translated into ordinary language, one knot means the speed at which a ship travels one nautical mile in an hour. At first its value was 1853.184 meters. This is exactly the length of the Earth's surface along the meridian in one arc minute. It was only in 1929 that the International Conference in Monaco established the length nautical miles at 1852 meters.

It must be remembered that, in addition to the nautical mile, there are others. In the past, several dozen different miles existed as units of measurement for length in different countries. After the introduction of the metric system, miles as a unit of measurement of distances began to rapidly lose popularity. Today, out of all the variety of land miles, only about ten remain. The most common of them is American mile. Its length is 1609.34 meters.

Not only the nautical mile is tied to the length of the earth's meridian. The old French unit of length, nautical league, is equal to 5555.6 meters, which corresponds to three nautical miles. It is interesting that, in addition to the sea league, in France there was also a land league, also tied to the length of the meridian, and a postal league.

Speed ​​recalculation rules

Today, the speed of sea vessels is still measured in knots. In order to present this characteristic in a form familiar to us, it is necessary to convert them into kilometers per hour. It can be done in several ways:

1. Simply multiply the number of nodes by 1.852 in any way possible, for example using a calculator.
2. Make a rough calculation in your head by multiplying the number of nodes by 1.85.
3. Apply special translation tables from the Internet.

Having made such a recalculation, it is easy to compare the speeds of sea vessels and other vehicles.

Record holders among ships

The speed of sea passenger ships is usually higher than that of commercial ships. The latest official record (“Blue Ribbon of the Atlantic”) belongs to the American high-speed transatlantic liner "United States". It was installed in 1952. Then the liner crossed the Atlantic at an average speed of 35 knots (64.7 km/h).

The infamous Titanic, on its only voyage, was sailing almost at the limit of its technical capabilities at a speed of 22 knots when it hit an iceberg on the night of April 14-15, 1912. The highest speed of passenger liners at that time (Mauritania and Lusitania) was 25 knots (46.3 km/h).

Here are some of the ships that were once winners of the Atlantic Blue Ribbon:

1. Great Western (Great Britain) in 1838.
2. "Britannia" (Great Britain) in 1840.
3. "Baltic" (Great Britain) in 1873.
4. "Kaiser Wilhelm der Grosse" (Germany) in 1897.
5. Lusitania (Great Britain) in 1909.
6. "Rex" (Italy) in 1933.
7. Queen Mary (Great Britain) in 1936.

There is a separate category of ships - hydrofoils, which are used for passenger transportation and coast guards. They can reach speeds of over 100 km/h (60 knots), but their range of use at sea is severely limited to the coastal zone and low economic characteristics.

Changing priorities

With the development of aviation, such active competition among ocean-going passenger ships has lost its relevance. Passengers began to prefer airplanes to cross the Atlantic, and ship-owning companies had to reorient themselves to serving tourists. For cruise ships, the most important indicators are reliability, comfort and economic efficiency.

The optimal speed of modern ocean cruise ships is usually from 20 to 30 knots, and for cargo ships - approximately 15 knots. A record achievement for that time, United States remains the highest in history. For merchant ships today, the priority indicators are primarily economic. The pursuit of records is finally a thing of the past.

Video

In this video collection you will find a lot of interesting information about measuring the speed of maritime transport.

Knot (unit of measurement)

Aircraft speed indicator, graduated in knots.

The prevalence of the knot as a unit of measurement is associated with the significant convenience of its use in navigation calculations: a ship moving at a speed of 1 knot along the meridian passes one arc minute of geographic latitude in one hour.

The origin of the name is related to the principle of using a sector log. The speed of the vessel was determined as the number of knots on the line (thin cable) that passed through the hand of the measurer in a certain time (usually 15 seconds or 1 minute). In this case, the distance between adjacent nodes on the line and the measurement time were selected in such a way that this amount was numerically equal to the speed of the vessel, expressed in nautical miles per hour.

A knot is an independent unit of speed. To say: “The ship is sailing at a speed of 36 knots per hour” is incorrect. The absurdity of such an expression is very well described in the story “The Flying Dutchman”, an excerpt from which is given below.
“Tell me, captain, what is our speed? - Raising his glasses from his notebook, the guest asked again.
Guzhevoy already opened his mouth to answer with his usual wit, that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:
“As much as it should be: full speed, twelve knots.”
The lag cable, released while moving from the stern, broke into knots at a distance of 1/120 of a mile (50 feet). By counting the number of knots that travel in half a minute (1/120 of an hour), you can find out the speed in nautical miles per hour. It follows that the expression “30 knots per hour” is clearly meaningless: it turns out that the ship, instead of a decent speed of 56 km/h, drags 1500 feet (470 m) per hour, which is both incorrect and offensive.

The hub and international nautical mile are widely used in maritime and air transport. Knots were considered the most common measurement in England until 1965, but later they became known as miles.

Notes

Wikimedia Foundation. 2010.

See what “Knot (unit of measurement)” is in other dictionaries:

KNOT, 1). In anatomy, thickening or enlargement of an organ or tissue, such as a lymph node or sinoatrial node, of nervous tissue that controls the rhythm of the heart. 2). In botany, a node is a place on a plant stem from which a leaf or leaves arise. 3) ... Scientific and technical encyclopedic dictionary

Knot: A knot connecting and intertwining linear materials. “Gordian knot” is a catchphrase. Contents 1 Communications 2 Science and technology ... Wikipedia

- (Knot) 1. Any grip or noose made on the tackle or around anything; connecting the ends of the cables together. W. woman's knot (Grannies knot, carrick bend) incorrectly tied straight or reef W. bowel (Bowline hitch) reliable,... ...Nautical Dictionary

A knot is a unit of speed equal to one nautical mile per hour. Since there are different definitions of a nautical mile, a knot can have different meanings. By international definition, one knot is equal to 1.852 km/h (exactly) or... ... Wikipedia

A knot is a unit of speed equal to one nautical mile per hour. Since there are different definitions of a nautical mile, a knot can have different meanings. By international definition, one knot is equal to 1.852 km/h (exactly) or... ... Wikipedia

Noun, m., used. compare often Morphology: (no) what? node, what? knot, (I see) what? node, what? knot, about what? about the node; pl. What? nodes, (no) what? nodes, what? nodes, (I see) what? nodes, what? knots, about what? about knots 1. A knot is called a tightened... ... Dmitriev's Explanatory Dictionary

List of nodes is a list of nodes in alphabetical order. Contents 1 A 2 B 3 C 4 D 5 E ... Wikipedia

The nautical mile is a unit of distance used in navigation and aviation. The nautical mile was originally defined as the length of a great circle on the surface of the globe measuring one minute of arc. Thus, moving to... Wikipedia

kinematic units- ▲ unit of measurement is speed knot. gal is a unit of acceleration. hertz unit of frequency... Ideographic Dictionary of the Russian Language

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 past, the UK often used its own nautical mile, 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), the number of knots that went into the water was counted.

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.

You probably want to know specific numbers as soon as possible? Well, let's not bore you with long conversations.

Boeing 737 takeoff speed

Let's figure out how fast a plane takes off. It all depends on individual technical characteristics.

If we talk about the Boeing 737, then takeoff is divided into several stages:

1. The plane begins to move only at the moment when the engine operates at a speed of 810 revolutions per minute. Once this point is reached, the pilot slowly releases the brakes and keeps the control lever at neutral.
2. Speed ​​is gained when the aircraft moves on three wheels.
3. Liner accelerates to 185 kilometers per hour and moves on two wheels.
4. When the acceleration reaches 225 kilometers per hour, the ship takes off.

The above indicators may fluctuate slightly, since the speed is affected by the direction and strength of the wind, air currents, humidity, serviceability and quality of the runway, etc.

You can find out the take-off speed of other airliners from the table:

We invite you to watch this video with a visual measurement of the speed of a passenger plane taking off using GPS:

Airplane speed when landing

As for the speed of the aircraft during landing, this is a variable value that depends on the mass of the side and the strength of the headwind, but in the average landing speed is 240-250 km/h, that is, approximately 20 km/h below the take-off speed of the aircraft.

If there is a headwind, the speed may be even lower, because the headwind increases the lift, in which case values ​​from 130-200 km/h are quite acceptable.

Speed ​​of a passenger aircraft in flight

So, the average speed of modern airliners is 210-800 kilometers per hour. But this is not the maximum value.

Cruise and maximum values

The acceleration of passenger airliners is divided into cruising and maximum. This value is never compared to the sound barrier. Passengers are not transported at maximum speed.

Speed ​​characteristics vary depending on the airliner model. Average values:

• Tu 134 - 880 kilometers per hour;
• IL 86 - 950 kilometers per hour;
• Passenger Boeing - accelerating from 915 to 950 kilometers per hour.

By the way, the maximum value for civil air transport is approximately 1035 kilometers per hour.

Passenger airliners have low cruising and maximum speeds, so you don’t have to worry again before your upcoming flight!

Passenger aircraft flight speed - quick reference:

• Airbus A380: maximum speed - 1020 km/h, cruising speed - 900 km/h;
• Boeing 747: maximum – 988 km/h, standard flight speed – 910 km/h;
• IL 96: maximum – 900 km/h, cruising speed – 870 km/h;
• Tu 154M: maximum speed – 950 km/h, average – 900 km/h;
• Yak 40: maximum – 545 km/h, and normal speed is 510 km/h.

You may find it easier to understand the numbers thanks to the table:

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