Why the speed of sea transport is determined in knots
On land, speed is determined in kilometers or miles per hour, but when it comes to measuring the speed of water transport, the count is kept in some mysterious “nodes”. Where did this name come from and what does it correspond to in our time. In order to understand this, one should turn to maritime tradition and history.
At the dawn of seafaring, no special instruments existed for determining the position of a ship at sea. At first, ships moved exclusively along the coastline. Over time, sailors learned to determine their location in large water, namely longitude and latitude. Just recall that latitude is the distance north or south of the equator of the planet, and longitude is the distance east or west of the prime meridian. However, at first, and in this system, everything was not easy and not perfect.
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 which they set off. Then a special device appeared – a ship’s lag. It was used to determine the speed of the ship. The first logs were an ordinary log with a rope. The lag was thrown overboard, and knots were tied on a rope at regular intervals. So the speed of the ship was calculated.
As you can already guess, it is from here that the maritime tradition went to designate speed in “knots”. Of course, in those days, the sea knot was not a standardized value. This happened much later, when more advanced measuring instruments began to appear. The name remains, despite the fact that the knot, in fact, was equated to one nautical mile per hour. However, it is worth remembering that the nautical mile is slightly larger than the land mile. Its length is 1852 meters.
The nautical mile itself corresponds to one angular minute (1/60 of an angular degree) of the meridian at the equator.
As for modernity, the device for measuring the speed of the ship is still called the lag. However, this is not the same piece of wood with a rope as hundreds of years ago. Today, this unit looks like a spinner. It is immersed in water and determines the actual speed of movement, and data is transmitted to a pointer 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.