In 1983, sailing a Tornado 'classic', I set the (still unbeaten) record time of 57mins for a 20+ mile all-in race run by Benfleet Y C called the Nore race. Conditions were 3-5 NW, giving us two long reaching legs, two broad reaches and one beat. my calcs are usually rubbish but I think we averaged around 23knots? We spent a bit of the first broad reach leg busting through the earlier cruiser start (it didn't take long) and had to heave-to for about two minutes at one point on the upwind leg to pop the main back on the halyard lock. I KNOW that 25 knots + is possible in F18 and bigger and would not be surprised at figures of 33 knots being quoted (but not for long periods)