1989 150hp Yamaha. Prop Pitch???

[Asainz320]

I have a 1989 150hp Yamaha oh my 2100 DC Century. The boat by it self its about 2500 lb. Right now im running a 19p prop, my max RPM is 4300 and max speed is around 35-40. I dont think the hole shot is that good.

Do you guys think i should go to a 17p prop?

 

[walleyehed]

Re: 1989 150hp Yamaha. Prop Pitch???

Well, my first thought when seeing an engine turning 1500RPM less than it should, I would verify the tach....but after punching in your numbers and using 12% prop slip, I do come up with 38mph @ 4300rpm with the 19P.

I'm thinking back to my Texoma days about a 21ft boat similar to the Century...can't remember the make...anyway, this rig had a 2003 Johnson 150 looper. I got to know the guy that owned this boat pretty well, and it always bothered me to see that engine setting on the transom...I asked him 1 day what prop he was swinging and it was a stock OMC 15X17...I asked him his rpm max and he said all he could get was 5200-and had terrible hole-shot to-boot.
I finally talked this gent into letting me assist him in raising the engine...we went up 2 holes but only got to 5350-still a killer for this engine. We ended-up going with a 15X15 on this rig and got to 5700....he wanted to stop there.

We need to know the make and model of your prop and that will help with some idea as to which direction to head. Just bolting on a 17P wheel isn't going to fix this.

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

Hey thanks for your reply.

I have no idea what the make or model for this prop is. I just know it's an aluminum prop with a 19m on it. The shape of it is the type that has staright edges on the wings and pointy tips, not rounded like the others.

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

It looks somthing like this:

 

[walleyehed]

Re: 1989 150hp Yamaha. Prop Pitch???

OK, that's the stock yammy prop.
Is this a newly rigged boat?

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

I bought this boat just like that, but thats not the engine that came with the boat since the boat is 1995 and the engine is an 89.

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

So...?

 

[jevery]

Re: 1989 150hp Yamaha. Prop Pitch???

Where I live there is a "Prop Shop" that does business with most of the Marinas in town. When I called to ask about a certain prop, he told me to drop by and he would take my credit card info and would loan me 3 to 5 props to try based on his knowledge of my setup and my description of my current numbers and what I wanted to change. When I decided if one worked well then I'd purchase it and return the others undamaged. Some boat dealers will also do this, but would not have the extensive inventory this shop has. Call around and try to borrow some 17s and some 15s before you lay down $300 - $400.

 

[Turbo1]

Re: 1989 150hp Yamaha. Prop Pitch???

Lets back up here. You say thats not the engine it came with. So who decided on the prop that is on it?

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

i guess that would be the guy that put the engine on the boat. I would guess they just left the prop this engine was using before.

 

[walleyehed]

Re: 1989 150hp Yamaha. Prop Pitch???

Give us some info as to what engine/prop you had before, and what kind of rpm were you getting with the previous combo?

 

[Asainz320]

Re: 1989 150hp Yamaha. Prop Pitch???

I bought this boat just like that, but thats not the engine that came with the boat since the boat is 1995 and the engine is an 89.

i mentioned that i bought the boat as is. I dont know how it would work out with a different pitch prop.

 

[walleyehed]

Re: 1989 150hp Yamaha. Prop Pitch???

I assumed you meant "that is not the engine that came with the boat"..when YOU bought it.
I venture to guess that boat had a 200+ on it before, and of newer technology.
If you have reason to believe the engine is running perfectly, you're going to need to drop to about a 15P.
If you had a 200/225H.O. on there, I'd say a 19 would be close.