RPM question
 

Hey guys, So while replacing my water pump on one of my motors today i ran across the info stamp on my motor and read that its only rated for 4200-4600 rpm's.. however with my current prop set up im spinning at about 5-5400. so am i correct in thinking i need to reprop my boat? im currently running a 20p 3 fin on both CW rotating drives. i do 64mph with that set up. If i were to go to a lets say 23p? would that bring down my rpm's? and increase the speed slightly or will that decrease the speed? thanks!

You shouldn't be turing that much on a stock older set up. Yes it can do it, but not good to do it for long. It should bring the speed up if the engines can spin them. 1'' in pitch on a prop is usually good for about 200 RPM drop.

John jr

Bought it with that set up just trying to get her "right" and finding out all the info as i go. i dont see a 23p being too much of a problem with the 350mags, that should bring me down to roughly 4600rpms with the 200 drop math. anything i should look out for etc? any suggestions on what to do Thanks again!

I'd first determine what my drive ratio is and verify my tachs for accuracy against a shop tach. Then you can better determine what pitch props are appropriate for your boat.