Why do you use nautical miles?

Answer 1

So if the statute mile is the result of Roman influences and plowing oxen, where did the nautical mile get its start?

Each nautical mile originally referred to one minute of arc along a meridian around the Earth. Think of a meridian around the Earth as being made up of 360 degrees, and each of those degrees consists of 60 minutes of arc. Each of these minutes of arc is then 1/21,600th of the distance around the earth. Thus, a nautical mile is 6,076 feet.

Answer 2

Nautical miles are only used when on the water.