I own a Ribcraft 585.
for some of what my Boat has been upto.
Excellent boats, I have pushed this boat and it has performed just great.
I have a Suzuki 140 four stroke on the back and the boat is capable of in excess of 40knots (when the sea is right)
Can't offer you a trip this weekend but hope to be out on the water the end of next week in Exmouth / Torquay area if you are in that area.