Need help picking a prop!

[jamieat]

I have a 2004 Yamaha 2-stroke 90 hp outboard on a 17.5' xpress bass boat. I was getting about 44mph out of the boat and I recently added a power lift jack plate. This increased my speed to around 50 but increased my rpm's by around 600. I am currenly running a 3-blade power tech 13.25" 17 pitch prop. This prop is turning at plenty of rpm's and I am wondering if I can run a 20 or 21 pitch 4 blade 13.25" prop on this motor and increase my top end speed. What would be too much prop for this set up. By the way, the jack plate makes all the difference in the world in handling, hole shot, and top end speed. Plenty of rpm's!

 

[JARB]

Re: Need help picking a prop!

Hello jamieat!

I have the same engine and a boat in similar size as yours. You can read about it in the thread "Tried 2 props, what do I try next?" here at this section. I think you should try the Yamaha Pro Series in the 13,5 X 19 size or maybe even a 21. I tried a 19 on my boat and the grip in the water and the lift of the boat was incredible. Sadly I could only turn it to 4600 rpm but I have no jack plate.

I am a little curious what blade design you got on the PowerTech prop and how high you raise your engine. Are your speed from a speedometer or GPS? I am thinking maybe a PowerTech PTR in 17 pitch could be something for me. Also thinking about getting a jackplate. If I also could get 600 rpm from a jackplate I could turn my Pro Series to the correct rpm.

I leave the four-blade question to someone else with better knowledge than me to answer.

Greetings from SWEDEN!!

 

[jamieat]

Re: Need help picking a prop!

Thanks for the response, I have contacted customer service @ Iboats about making my selection. They explained to me about the difference between a 4 & 3 blade. 4 is definately better but reduces your rpm a little. I am currenly running a power tech part # YM90RED3R17S 17 pitch 13.25 dia Power Tech propeller. I have a power lift manual jack plate that is rated for up to a 300 hp motor. The jack plate worked wonders, the best investment I have put into the boat as of yet. Now if I can just get the prop to match. I am running about 54-55 on the speedometer with the jack plate v/s about 48-49 with out. My rpm's jumped significantly. I cannot tell expactly how much b/c my tach got stuck b/f I installed the jack plate. I am working to fix this however so that I can tell the difference in rpms before I make a prop selection. I was running the 17 around 4800 before and I would guess around 5400 with the addition of the jack plate.