Kevin
I'm Running a 25" shaft 250hp with a 3 blade S/S 17" Viper Prop without a bracket on my 23'. I have a T-Top, full fuel of 135 gal and 15 gal water and equipment:
According too GPS and system matched gauges, here's my numbers. I will match these numbers again later this year after mounting the same motor and prop on the Potter Bracket:
RPM GPS MPH
3500 13.5 (not planed off)
4300 30.0 (cruise)
4500 33.4
5000 37.9
5400 40.5
5900-6000 46.0 (Trimmed)
Don't shoot from the hip
you can get some test props from your dealer and try them out and then purchase the S/S expensive one that gives you the best performance.