Originally Posted by kwil
It comes with a Stainless Viper 13 7/8 x 17", you may find this is too fine a pitch and may need to go to 19", I did as it would easily rev to 6000+. The 19" prop has not taken to much off the acceleration but give a very economical cruising range at 3500-4000 revs.
Yes I found the 17" viper on a 5.25 Rib gave me about 5,800 RPM this is a little on the high side albeit still in the recommended range, I found the best prop for this engine on my RIB was the BRP 18" Raker SS although any 18" should give you an the ideal RPM of around 5,600. I got 40 - 41 knots out of this setup.