Kts in km hour. What is a nautical mile and what is a knot equal to? Record holders among ships

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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.

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.

Wind(the horizontal component of air movement relative to the earth's surface) is characterized by direction and speed.
Wind speed measured in meters per second (m/s), kilometers per hour (km/h), knots or Beaufort points (wind force). Knot is a maritime unit of speed, 1 nautical mile per hour, approximately 1 knot is equal to 0.5 m/s. The Beaufort scale (Francis Beaufort, 1774-1875) was created in 1805.

Direction of the wind(from where it blows) is indicated either in points (on a 16-point scale, for example, north wind - N, northeast - NE, etc.), or in angles (relative to the meridian, north - 360° or 0°, east - 90°, south – 180°, west – 270°), fig. 1.

One sea knot is equal to one thousand eight hundred fifty-two meters or one kilometer eight hundred fifty-two meters

By international definition, one knot is equal to 1.852 km/h (exact) or 0.5144444 m/s. This unit of measurement, although non-systemic, is allowed for use along with SI units.

A knot is a linear speed of 1 nautical mile per hour.

one sea knot is equal to 1852 meters => 1 km 852 m

The origin of the name is related to the principle of using sector lag. 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).

Knots do not measure distance but speed, number of knots = number of nautical miles per hour, nautical mile = 1.8 km.

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 after a re-decision they became known as miles.

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 the shape of the Earth is somewhat different from the outline of a perfect sphere, the length of 1 minute of 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.

1 sea knot is equal to:

• kilometer per second (km/s) 0.0005144
• meter per second (m/s) 0.5144
• kilometer per hour (km/h) 1.852
• meter per minute 30.87

You can find out the speed from 0 to 100 nautical knots converted into km/h and m/sec in this table:

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 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 speeds 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).

true airspeed (TAS)

The actual speed at which the aircraft moves relative to the surrounding air due to the thrust of the engine(s). The velocity vector in the general case does not coincide with the longitudinal axis of the aircraft. Its deflection is affected by the angle of attack and the aircraft's slip;

instrument speed (IAS)

The speed indicated by the instrument that measures airspeed. At any altitude, this value unambiguously characterizes the load-bearing properties of the glider at a given moment. Meaning indicated speed used when piloting an aircraft;

Ground speed()

V1 depends on many factors, such as: weather conditions (wind, temperature), runway surface condition, take-off weight of the aircraft and others. If the failure occurs at a speed greater than V1, the only solution is to continue the takeoff and then land. Most types of civil aviation aircraft are designed in such a way that, even if one of the engines fails on takeoff, the remaining engines are sufficient to accelerate the aircraft to a safe speed and rise to the minimum altitude from which it is possible to enter the glide path and land the aircraft.

Va

Estimated maneuvering speed. The maximum speed at which full deflection of the control surfaces can be achieved without overloading the aircraft structure.

Vr

The speed at which the front landing gear begins to rise.

V2

Safe speed for takeoff.

Vref

Design landing speed.

Vtt

Specified speed of crossing the runway leading edge.

Vfe

Maximum permissible speed with flaps extended.

Vle

Maximum permissible speed with landing gear extended.

Vlo

Maximum landing gear extension/retraction speed.

Vmo

V maximum operating - maximum operating speed.

Vne

Unexceedable speed. The speed indicated by a red line on the airspeed indicator.

Vy

Optimal climb speed. The speed at which the aircraft will reach its maximum altitude in the shortest time.

Vx

Optimal climb angle speed. The speed at which the aircraft will gain maximum altitude with minimum horizontal movement.

Vertical speed

Change in flight altitude per unit time. Equal to the vertical component of speed