The aluminum prop that came was a 3 blade 17 pitch. The boat would only get around 38 mph and 3600 RPMs as I trimmed it up and then it wouldn't dig anymore and start spinning. I replaced it with a 17 pitch stainless Mercury Enertia 3 blade at Propgods Ken's advice. Took it out today and it averages around 42 mph and is still digging at 6000 RPMs. Much better.