Quote Originally Posted by Philippus Flavius Homovallumus View Post
For example, a Nautical Mile is is 1/60th of the distance between two line of latitude, or one navigational Minute, this is then divided into 10 cables, Cables being a usable measure at see. So, if you know the location of one ship and then run a cable to another ship, and take a bearing, you can likewise detmine the location of the other ship even without making any observations from it. This has navigational implications with regard to undersea hazards and is generally useful.

By contrast, the Statue mile is 1/3 of a League on land, which is the distance a man can walk in an hour. One explanation for the variation of the length of a mile is the difficulty in traversing the ground (and therefore the time taken) in different parts of the country.
The modern nautical mile is derived from the metric system: it's defined as exactly 1852 metres whereas you can only give an approximate conversion in yards or feet. It was established at an international convention and is included in the SI system, the traditional imperial unit is obsolete.

Having 1.000 different kind of measurements for different crafts and professions might be beneficial for those people themselves, but not for others who are trying to make sense of it. If I want to buy a rope, it would be much preferable to measure it in a unit that is clear and understandable to everyone rather than some arbitrary measurement that's only relevant to salesmen in the 17th century. In a few cases (such as the nautical mile) it might be worth to use a non-typical measurement, but otherwise it's much preferable to use universal, decimal units.

I wonder why I bothered to reply though...PVC seems to ignore my posts.