Need Advice on proper Prop Pitch

[mikey456]

I have a 200 OceanRunner. 25 inch Shaft on a 22Ft Bow Rider. WOT is 5200rpm. Top speed is 35MPH. After mounting the Motor this past year, I had to adjust the Motor for proper height with hopes there would be an increase in speed. However, after proper adjustment Speed stayed the same. My current Prop is a Stainless Steel 14.5X17.
I have seen boats that looked slightly larger than mine with a 14.75X19 on same HP Motor. I have also seen Twin 150HP
motors with 14X21 on same size boat. I wanna increase the speed to about 40MPH. I dont know the weight of my Boat other than to say Its hard to move it at the Dock when tying it up. And when I step in, it doesnt lean. So Im figuring 2500LB? Can I get some input from others who have similar setup as to what size and pitch I should get? And is it Stainless or Aluminum. Tks

 

[BaileysBoat]

Re: Need Advice on proper Prop Pitch

You didn't say what year but I found specs for a 1988 Ocean Runner 200. If the specs are the same: 1.86 drive ratio, 6000 max at WOT you have 24% slip. Usually at WOT slip is less than 10% and often below 5% if the set up is correct.
No way could you run a higher pitch with the present setup. Are you sure the engine height is correct? Is the boat heavy with wet foam? What is the max HP for the hull? Be nice to know what kind of boat and some pictures.

 

[catfishr1]

Re: Need Advice on proper Prop Pitch

Yup, need to see some pics .Also include some of transom, with motor in approx.approx running position.

 

[steelespike]

Re: Need Advice on proper Prop Pitch

We need the brand and year of the boat? Is the dead rise about 18 or 20 degrees? The year of the motor.
How is the hole shot?
Looking at boats of similar size,and about 3000 lbs.and 200 hp it appears props around 17" are typical with rpm ranges from 5300 to 5800
with speeds over 40 mph. typical slip from 15% to about 4% ,15% is high normal 4% low normal. As suggested your slip is high.
As rpm goes up slip will usually go down .A poor prop or a dirty or rough bottom or a load of water might cause your high slip mumbers.
If your motor has issues it may account for the relatively low rpm and higher slip.
If the motor is setup too low on the transom could contribute to some performance issues.

 

[mikey456]

Re: Need Advice on proper Prop Pitch

The Boat is a 1988 Custom Craft. The Motor is a 1998 Johnson Oceanrunner. When I slam it to WOT from Idle, it jumps up to 3800 or so and I have to keep the trim all the way down to get the boat on plane. Otherwise, the motor will just cavitate. Once on plane, I raise the trim up but not too much. The motor will cavitate at WOT. The Boat has a lot of foam underneath and is quite solid.

 

[Silvertip]

Re: Need Advice on proper Prop Pitch

If you are blowing out at WOT you are either trimmed too high or the engine height is set too high. With the engine turning only 5200 rpm at wide open throttle you cannot go with more pitch. WOT for that engine should be in 5800 - 6000 rpm range. As was mentioned, an engine that is down on power will cause poor performance and fuel economy will be poor as well because you are forced to run at higher throttle settings than normal.

 

[steelespike]

Re: Need Advice on proper Prop Pitch

Your motor is ventilating; cavitation is a different thing that doesn't directly affect performance.
I wasn't able to research your model but the heaviest 21-22 ft in 91 was 2400 lbs.
Not terribly heavy for a 200 hp motor.
Have you tried lowering the motor one hole?
I'm no real expert but your prop doesn't impress me
it appears a little tired.You ,might take it to a prop shop for their opinion. They may be able to add some cup
to ease the ventilation.
I think your slip will improve if the setup or prop improvement allows more trim.
being able to really trim up better could easily add 5 mph.

 

[mikey456]

Re: Need Advice on proper Prop Pitch

Thanks for the replies. No I wasnt impressed with the prop either. It looked tired when I bought the motor. Wanted to get a season out of it last year. Im gonna replace the prop with same pitch and all come spring. thanks again.