Go to the link :

http://www.macquarie.com.au/speedsailing/updates.htm

and look at this graph.



As you can see, the boat was still fully accellerating when it reach 46 knots of speed. Normally one expects ar levelling out of speed (reduced accelleration) when close to a top speed. This graph isn't showing that yet.

This plot indeed suggests that MI is capable of 50+ knots speeds with relative ease, apparantly the trick is to AVERAGE 50 knots of speed over a 500 mtr stretch.

Wouter