[McGillicuddy]

Not sure who you rode with but I'm with Blackfin on this one. Both of those configs would be easy to screw up. The Yanmar conversion was probably not designed for speed, so throw that out - although my guess is that it rode like a dream. The bracketed OX66 225 my have been mounted too low or improperly propped or a poor bracket design or missing a cylinder, etc.

I really can't imagine a Sceptre with any healthy 225 not being able to cruise at 20+ knots and top out at close to 30 knots. the other thing is how ofter are you really cruising at 25 knots on Buzzards Bay.