The U.S. adopted the worldwide nautical mile in 1954. Proven right here: NOAA Ship Pisces is the third in a category of state-of-the-art, acoustically quiet fisheries survey vessels constructed for a variety of residing marine useful resource surveys and ecosystem analysis initiatives.
Nautical Miles
Nautical miles are used to measure the gap traveled by the water. A nautical mile is barely longer than a mile on land, equaling 1.1508 land-measured (or statute) miles. The nautical mile relies on the Earth’s longitude and latitude coordinates, with one nautical mile equaling one minute of latitude.
However why use a unique measurement system for marine navigation? Utilizing latitude and longitude coordinates is extra sensible for long-distance journey, the place the curvature of the Earth turns into a think about correct measurement. Nautical charts use latitude and longitude, so it’s far simpler for mariners to measure distance with nautical miles. Air and house journey additionally use latitude and longitude for navigation and nautical miles to measure distance.
The phrase “mile” may depart you questioning if there’s a “nautical kilometer,” too. There’s not. The worldwide nautical mile is used all through the world. The measurement was formally set at precisely 1.852 kilometers in 1929 by what’s now referred to as the Worldwide Hydrographic Group. The U.S. and the UK each used barely completely different measurements after that point, however the U.S. adopted the worldwide nautical mile in 1954 and the U.Okay. in 1970.
Knots
Measuring the knot within the seventeenth century.
Knots, alternatively, are used to measure pace. One knot equals one nautical mile per hour, or roughly 1.15 statute mph.
The time period knot dates from the seventeenth century, when sailors measured the pace of their ship utilizing a tool referred to as a “frequent log.” The frequent log was a rope with knots at common intervals, hooked up to a chunk of wooden formed like a slice of pie. Mariners would decrease the wooden piece into the water and permit it to drift freely behind the ship for a particular period of time (typically measured with an hourglass). When the time was up, they’d rely the knots between the ship and the piece of wooden, and that quantity estimated their pace.