From: Robert Deering <deering@ak.net> As a sidenote, Dennis Raedeke told me that on his Wildwind IV powercat, he experienced significant "slamming" on the underdeck towards the stern. I would have expected wave impacts towards the bow, but after thinking about it, I think the cause of that slamming was from the two wakes colliding under the hull and creating a vertical jump before they cleared the back of the wing deck. Haven't confirmed that yet with Dennis. I'm guessing that too is a function of hull separation, length, and speed, as well as displacement and hull shape. ____________________________________________ Brian wrote; You are right, a major portion of the slamming occurs toward the rear of the wingdeck, and as a result of the two colliding wakes. These wakes are increased in size as the 'fatness' of the hulls increase. Brian Eiland beiland@usa.net www.RunningTideYachts.com distinctive expedition yachts