A nautical mile is defined as a unit of length based on the circumference of the earth which is equal to a single minute of latitude. A nautical mile is not a mile of statute (one mile measured on land). Nautical miles are most commonly used in navigation and cartography, especially on water. Compared to the mile statute, a nautical mile is slightly larger. Previously, there was no internationally defined conversion recognized between a nautical mile and a mile statute. During that time, the United Kingdom and the United States used different definitions. However, since 20 thcentury, a nautical mile is defined internationally equal to the miles of the statute 1.1508. Compared to meters, an internationally defined nautical mile equals 1,852 meters.
A node is a unit of speed based on the nautical mile. A knot is equal to one nautical mile per hour. Therefore, a node is equal to state miles 1.1508 per hour (1.1508 mph). The internationally recognized symbol for the node from the ISO and the Institute of Electrical and Electronics Engineers is kn. Some people use another common symbol of the node which is referred to as kt. The node is most commonly used in maritime and air navigation and in meteorology. A coating in the sea that travels at a speed of 1 kn along a meridian-marked path is said to travel at least one minute of geographical latitude in an hour.
What is the origin of the knots?
The term “nodes” has a maritime origin. In the past, sailors did not have modern navigation and measurement speed technologies while at sea. Instead, they used a simple tool called the common register to approximate the speed of ships at sea. The common trunk was simply a roll of rope with knots tied at evenly spaced distances. The rope was then joined to a piece of wood in the shape of a slice of cake. The wooden end was then thrown into the sea so that it could float. The rest of the coil unrolled gradually as the ship sailed. The coil was left unrolling for a certain period of time which was determined by an hourglass. After the specified time was exhausted, the rope was rewound into the ship. The sailors then calculated the number of knots between the piece of wood and the ship. The ship’s speed was the number of nodes counted. Based on the current knowledge of a node, it is safe to conclude that the distance of the intervals between the nodes was close to a nautical mile. The reason for this conclusion is that, at that point, the nautical mile had not been defined and accepted internationally.
Most professionals do not use nodes among non-professionals because it is not a widely understood unit. Instead, professionals usually convert measurements.
Conversion to other units
A node (as defined internationally and accepted) =:
- Exactly 1,852 kilometers per hour.
- About 0.51444 meters per second.
- About 20.25372 inches per second.
- About 1.68781 feet per second.