On land, speed is determined in kilometers or miles per hour, but when it comes to measuring the speed of water transport, the account is kept in some mysterious "knots". Where did this name come from and what does it correspond to in our time. In order to understand this, one should turn to the maritime tradition and history.
At the dawn of navigation, there were no special instruments for determining the position of a ship at sea. At first, the ships moved exclusively along the coastline. Over time, sailors learned to determine their position in high water, namely longitude and latitude. Recall right away that latitude is the distance north or south of the planet's equator, and longitude is the distance east or west of the prime meridian. However, at first everything in this system was not easy and not ideal.
Longitude could always be determined by the polar star, but with latitude it was not so simple. In ancient times, sailors had to count it from the place from where they set off. At the same time, a special device appeared - a ship log. It was used to determine the speed of a ship. The first logs were an ordinary log with a rope. The log was thrown overboard, and knots were tied on the rope at regular intervals. This is how the speed of the vessel was calculated.
As you might guess, it is from here that the naval tradition came to designate speed in "knots". Of course, in those days, the nautical knot was not a standardized value. This happened much later, when more advanced measuring instruments began to appear. The name remained, despite the fact that the knot was, in fact, equated to one nautical mile per hour. However, it is worth remembering that a nautical mile is slightly larger than a land mile. Its length is 1852 meters.
The very same nautical mile corresponds to one angular minute (1/60 of the angular degree) of the meridian at the equator.
As for modern times, the device for measuring the speed of a ship is still called a lag. However, this is no longer the same piece of wood with a rope as hundreds of years ago. Today this unit looks like a turntable. It is submerged in water and determines the actual speed of movement, and the data is transmitted to a dial or digital indicator.
Want to know even more interesting things about maritime business? Then read about why sailors wear daggers and not something more "impressive" for battle on a ship.