A-Cat - I've been sailing/training with a Garmin GPS.

Upwind, 10-12 knots in flat water seems around the max.

Downwind - In flat water wild thing mode, I've seen 18 knots. Pete Melvin says 19 knots should be the max, they think the boat has gone 20 knots but not over that.

Last year at the Alter Cup Area D qualifier, I started a downwind leg ahead of Harry Newkirk on an I-20. We both gybed onto port gybe with Harry about 50 yards to weather. We both seemed to be going the same speed forward (I was flying a hull) but he was going five degrees lower so they slowly came down to me. This was in flat water.

I think the spinnaker boats go faster speed wise in waves because the A-cat gets stopped by the waves much easier while the spinnaker tends to power you through.

Not sure what top speed Hakan in Sweden has done with an A-cat with chute.

Bob Hodges
A-Class USA 230