Have a Skeeter ss90 (16.2ft). 1993 Johnson 90hp. It currently has a 13.25 x 19p aluminum prop. I am getting 45.2 mph with the wind behind me. I know that is good for this boat...no jackplate. Motor is almost 5" below pad.

I was wondering a couple of things. If I get a 6" jackplate...which I have on the way. And raise the motor up to at least start at 3.5"...but maybe find the sweet spot after that...Am I going to get more speed? What kind of effect should I get other than speed?

I spin that aluminum prop 5200-5300rpms at wot...45mph.

I also own a stainless 13.25 x 21p prop. It just needs a hub pressed in. Do you guys think with a jackplate and motor raised, that I will also be able to spin the stainless one up over 5000 rpms?

Id like to use the stainless prop...if my motor has enough power to spin it.

thanks

No yes no maybe.
First you�re going to lose 300-400 rpms with your other prop setup as is.
3 1/2� is probably going to be too high. Your V4 doesn�t twist as large a prop as a V6 so it just can�t run as high.
The correct answer is find another 19 stainless for your motor, that aluminum can never find potential.
Then take the time with a fishing load to find your right spot. Set it where it is and raise 1/4� at a time until you lose lift, speed or water pressure. The only way to do it right.

Where would you recommend as a starting point with the V4 engine? 4"?

Your prop dictates motor height.
Aluminum can�t run as high as stainless. And to confuse more the same pitch stainless will usually not run equal rpm as aluminum because the blades don�t flex.

Proper setup takes some time to be correct.

Thanks Pat... appreciate your info always!