Speed of a Knot

Date: 06/10/99 at 13:26:45
From: mo
Subject: Speed of a knot

How fast is a knot?

Date: 06/10/99 at 15:49:59
From: Doctor Rick
Subject: Re: Speed of a knot

Hi, Mo.

A knot is one nautical mile per hour. 

  1 nautical mile = 6076.115 feet
                  = 1.150779 statute miles
                  = 1.852 km (exactly)

so 1 knot = 1.15 mph = 1.852 km/h.

The length of a nautical mile is defined as the length of 1 minute 
(1/60 degree) of latitude; being not that far from a statute mile 
(5280 feet), it was given the same name. But the nautical mile is the 
natural unit of distance to use at sea, where one's position was found 
in terms of latitude and longitude by celestial navigation with the 
sextant. Therefore the knot was the natural unit for measuring speed 
at sea.

The name of the knot comes from the means of measuring a ship's speed. 
Sailors would heave a log into the water attached to a rope. The rope 
had knots in it, and a sailor would count the knots that passed 
through his hands in a certain amount of time. The book in which speed 
(measured by heaving the log) and position were recorded was called 
the ship's log, so there are at least two terms that came from this 
practice.

- Doctor Rick, The Math Forum
  http://mathforum.org/dr.math/