So it could have made about half that speed if they'd just set up sails and run before the wind?
I doubt that... The fastest I have been able to go on my Nonsuch (5 ft draft) is about 10 knots down wind with a 25 knot wind with 3-4 waves however my friends claim I’m lying.
World Sailing Record for l’Hydroptère!
France - With peak speeds reaching an amazing 55.7 knots, l’Hydroptère has shattered the world speed sailing record* with an average speed of 51.36 knots over 500 meters. This not only trounces the Macquarie Innovation speed of 50.07 kts (the fastest boat), but in the ongoing battle between big and small, the giant hydrofoil has become the fastest watercraft under sail, besting the 50.57 kts recorded by Alexandre Caizergues on his kite-board last year. With record-making season just beginning, the bar has been set high by the mighty Hydroptère and her crew...
http://yachtpals.com/sailing-hydroptere-7018