A ship’s speed is measured in knots because it is a unit of speed historically used in navigation, tied to the maritime tradition. The term originates from a method sailors used in the past to measure speed at sea.
The History
• Sailors used a device called a log line, a rope with evenly spaced knots tied along its length.
• The log line was thrown into the water, and as the ship moved, the number of knots that passed through a sailor’s hands in a specific amount of time (usually 30 seconds) was counted.
• This count determined the ship’s speed in “knots.”
Why Knots?
• A knot is equal to one nautical mile per hour.
• Nautical miles are based on the Earth’s circumference and are more practical for navigation because they are tied to the planet’s geography (1 nautical mile = 1 minute of latitude = 1.852 kilometers).
Using knots allows for consistency and precision in maritime and aerial navigation, making it the standard unit for measuring speed at sea and in the air.
