CAN ANYONE TELL ME WHAT SIZE PROPS TO RUN ON A 1991 29FT FOUNTAIN WITH TWIN BLOWN 454'S THAT DYNO AT 536HP 5300 RPM AND 83MPH ON GPS WITH THREE BLADE MARIGE BUT WOULD LIKE TO GO WITH 4 BLADES FOR HANDLING. THIS BOAT HATES FLAT WATER BUT THE BIGGER THE WAVES THE BETTER IT LIKES IT.

I've got a 1997 29' Fountain that I was going to put twin 500 hp's in, but I never did. I spoke w/ Fountain and w/ that setup, they recommended Hydromotive QIV 28 pitch. I would imagine for the non-stpped (as in your case), but 30 more horsepower, I would recommend the same. Check w/ Fountain, just to make sure. I do have the props if you want to buy..

GO- BIG so you have a pair of hydro 28p props? what shape are they in and the main ask question $. what I dont under stand is I had a 25p 3 blade on my last boat with a 502 and when I put a four blade on it I had to go one pitch smaller and cut the diameter down to get it to work and it did work great. but every one is telling me to spin one or two sizes larger than what I have. I call fountain to day but have not heard back.