BTW. the sail I am using is 3.4!! Never get wind strong enough to use it on the water! Although the photos dont show it we were probably doing about 40kph.
5.7m sail in around 10 knots.
It's good up until 16/17 knots at which point four wheel drifting starts getting a little too exciting!
Plus there's that strangely disconnected sense of mortality you get from doing 65km/hr on hard sand wearing only shorts and a t-shirt..