The Tornado class held a Worlds in Bermuda in 1997, after each race they had a thing called the Bacardi Blast, they had set a 100m course up just off the harbour wall, on the faster days it was boling offshore 20 -25 knots, water was perfectly flat. It was a beam reach and most teams recorded speeds of around 30 mph I think the top speed was a about 33. I don't know how acurately they measured the course, I was surprised at the speeds, but they were all consistent.

John