Bill,
Thanks for the note !
I'm going to pass on taking pi to 250 places, ha!
Part of my calculations are pure math, part represents a little history with the 38 hull, and part is my own experience with props and 427 motors. I have a lot of respect for CC engineering, and I would wonder why they chose the 2.5 and the 23x25 if 2.0 (and smaller props) would work better.
Therefore, we must assume they knew what they were doing, and I think that's a very safe assumption. You make some good points and I can't argue or take issue with them. My hunch is, I'll bet you can take a 454 setup with 2.0:1 gear reduction, and with the available selection of props at your disposal (including the 4-blade wild card) end up with a workable boat without too much of a sacrifice in speed or economy. If I were doing this for myself, I would not focus on top speed at all, but would work with someone like propellersonline.com to find the best cruising speed for the conditions I anticipated encountering on the water in my boating area. In the end, I think it will work, and I'm real interested in hearing exactly how this turns out. Good data, eh?
Regards,
Paul