Why mph and not knots?
(It is not "knots per hour", one knot = 1 nautical mile per hour)
If you are using any normal chart, it will be marked in nautical miles,
therefore knots are simpler to use.
Alternatively, just multiply by 1.151 to get mph.
HTH
Steve
Stephen C. Baker - Yacht Designer
http://members.aol.com/SailDesign/pr...cbweb/home.htm