Measures in sailing – what is a knot, how much is a foot, how much is a nautical mile?
Measures in sailing – what is a knot, how much is a foot, how much is a nautical mile?
A glossary of nautical terms abounds with many words that are not always understood by non-maritime people. What’s more, the vocabulary is so varied and appropriately also locally adapted that it is sometimes easy to get lost. Let us take you through the basics of the terms used in nautical measurements.
From this article you will learn:
- What is a knot (kt), what is its value, and what does it determine
- What is a feet (ft) and what is its value
- How much is a nautical mile (nM) and how it differs from a land mile
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What is a knot (kt), what is its value, and what does it determine
A nautical knot, or KNOT in English, is a unit of measurement that determines the speed at which a vessel moves on water. Knowing the English translation, it is worth adding that it is abbreviated as „kt” or „kn”.
The numerical value of a knot is the ship’s speed, properly represented, according to the following formula:
1 nautical knot= 1 nautical mile/h = 1.852 km/h ≈ 0.514444 m/s.
That is, to explain it is the distance covered in an hour equivalent to one nautical mile.
It is worth noting that knots can be found not only at sea. Some countries also use knots for air traffic.
What is a feet (ft) and what is its value
A feet in English for short, ft, is a unit of measurement that ranges from 29 to 32 centimeters in correlation to the human foot.
This discrepancy is due to cultural differences and those related to differences in the average lengths of different body parts in different corners of the world.
However, an averaged value of a foot that measures 30.2 centimeters is accepted.
Nevertheless, it is worth mentioning where this discrepancy comes from in practice. For example – the Polish Old Polish foot measures 29.7 centimeters, where the Lithuanian foot is already 32 centimeters. The Egyptian foot is 35 centimeters, and the Dresden foot is 28.3 centimeters.
How much is a nautical mile (nM) and how it differs from a land mile
A nautical mile is a unit of measurement used in navigation and determining the speed of a vessel’s movement on water. Moreover, the nautical mile is also used in aviation.
A nautical mile is exactly 1,852 meters long. Compared to a land mile, it is slightly longer, a land mile is only 1,609 meters.
The abbreviation NM comes from the English term nautical mile.
A nautical mile is a unit closely related to the globe, which, because it is a geoid, affects the measurement of a nautical mile. The length of this measure is related to the length of the arc of the Earth’s meridian, which in turn is a reflection of one minute of the great circle. Therefore, due to different measurements at different latitudes, the „classic” definition of a mile may change.
To prevent discrepancies, a universal unit was established. The International Nautical Mile, abbreviated INM, is a unit popularized by the International Bureau of Weights and Measures and corresponds exactly to 1,852 meters, which is considered the binding length of a nautical mile.
