Hi, I have a 20 ft by 50 inch tracker sportsman flat bottom boat. It's riveted and so not near the weight of a true mud boat. As a perspective a 20 hp go devil longtail pushed it about 12 with a few guys and a 16 hp swamp runner pushed it 14 with a couple guys. What kinda of speeds can I expect to get from a 25 prodrive or other surface drive? Trying to decide if it's worth the extra money and weight to get a 35 or if a 25 or so will do. Also I know that this hull isn't designed for mud motors and that I should get a welded hull but I've been running this one in shallow water for years with no problems and I plan to run it until it falls apart. Then I will get a new hull.
Thanks for the input.

23 mph or so would seem about it.