RPM range and prop pitch

[commok]

I need the best advice you experts can give me! I have a 18ft Sea Pro CC with a Yamaha F115. I just installed a Rapture 13x19 SS prop, took it out for a test run and noticed the RPM's only hit 5100 WOT, while with my original equip 13x19 aluminum prop, I would hit 5900 RPM's. The engine is supposed to run at 5000-6000 RPMs WOT, and from reading the postings here, I gather one should really keep it in the upper half of the RPM range, ie 5500-6000. I did gain a few mph (46 before, now 48), but am wondering if I should switch props or pitch. Engine longevity is my main concern, not top speed. What do you guys suggest? <br /><br />

 

[JB]

Re: RPM range and prop pitch

Howdy, Commok. Welcome to the board.<br /><br />Sounds like your SS prop is getting a much better bite than the aluminum. Not unusual. May be a cupped prop, which would perform like a 21" aluminum. <br /><br />Try a 17" cupped SS prop or go back to your aluminum 19".<br /><br />Red sky at night. . .<br />JB