15 versus 17 ??

[baitfish]

I have a 55hp. with a 12&1/4 by 15" prop. that does 33mph. how much could i expect to gain by going to a 11&3/4 by 17"? and how much difference is there in performance between a 3 blade prop and a 4 blade?? thanks alot,Alex...

 

[JB]

Re: 15 versus 17 ??

What engine do you have it on and what rpm are you turning at WOT, CC?

 

[baitfish]

Re: 15 versus 17 ??

HI,JB,Thanks for the reply.. it's a 1979 evinrude...i'm taking it in to shop monday to have a tach. installed.. i tried to hook one up but it wouldn't work?? replaced the rectifier, still wouldn't work??? a little history on this motor. when i got it wouldn't run at all..i switched the placement of the coils, now runs good?? by switching the coils did i screw something up?? thanks again.....Alex...

 

[Solittle]

Re: 15 versus 17 ??

You have the right prop when your motor delivers the maximum rated rpms at wide open throttle (WOT). Check the specs for your motor.