Nautical mile 1 sea mile", followed by "For most practical purposes distance is measured from the latitude scale, assuming that one minute of latitude equals one nautical mile". One tenth of a nautical mile is a cable length. The derived unit of speed is the knot, defined as one nautical mile per hour. The metre was originally defined as of the meridian arc from the North pole to the equator passing through Dunkirk. The Earth’s circumference is therefore approximately 40,000 km. The equatorial circumference is slightly longer than the polar circumference – the measurement based on this (40,075.017 km x x =
Nautical time Nautical time Nautical time refers to the systems used by ships on high seas to express their local time. Nautical time keeping dates back to the early 20th century as a standard way to keep time at sea, although it largely only applied to military fleets pre-World War 2. This time-keeping method is only used for radio communications and to account for slight inaccuracies that using Greenwich Standard Time (GST) may lead to during navigation of the high seas. Nautical time zones are split into one hour intervals for every 15 degree change in a ship's longitudinal coordinate. This is