One nautical mile equals to one minute of a meridian arc; every 60 minutes is one degree and you get the rest.

Regarding maximun Catamaran speed; John McKnight and a few others can attest I broke world records when I got caught in Gale force winds ( 40 + knots w/gusts over 50 ); I can attest the speed achieved was VERY SCARY to say the least.
After this I told John I will stop my research work; now I see a cloud in the sky and I do not go. I will just leave it to Steve Fosset.