Up until now I've just been a lurker.
I have a 1976 25 Deluxe which has a non-original but good running MD11C FWC (now for sale for $1000 if anyone's interested).
My issue has been it's under powered. When I load it up for a week's getaway I get 5.0kn maybe 6kn if the wind and current is in my favour. Otherwise I do love the boat and I've heard great things from owners swapping in these Betas to replace their MD17s.
I'm looking at gearing it 2:45 to 1. (Max engine speed is 2800rpm). I have the option of a smaller screw at 2:00 to 1.
My question is this: how large a diameter of prop can I fit onto this boat? Ideally I would go with a 18" x 13" at the 2:45 to 1 ratio. Does anyone here know what the vertical measurement is from the hull to the center of the propeller? I ask because I haven't hauled the boat out yet and don't plan to for another 2 weeks.

Any comments are also appreciated!!

Cheers,
Robert