Is a 15 pitch prop too low

[swirly]

Hey guys. I've got a 1992 seaswirl 190se with a 5.8 351 omc that I purchased last year. I'm currently running a ss 18 on it. I only use this boat for wakeboarding and pulling the kids on tubes. I just had this for half the season last year, but it seemed to lack the hole shot and time to plane I thought it should have(exhaust is also straight piped through the hull). After getting some valuable info on these forums I was ready to get a 4 blade rubex with a 15 pitch. I ran this by my mechanic(he's worked on omc's for better than 25 years) and he felt strongly that it would tach out and I wouldn't go anywhere. The wot is 4000-4400 and my elevation is around +4800. I'm not at all concerned about the top end. Any recommendations would be great.

 

[rrhodes]

Re: Is a 15 pitch prop too low

Are you saying that your current WOT rpm is 4000 to 4400 or that is what your engine is rated for?

 

[swirly]

Re: Is a 15 pitch prop too low

That's what it is rated for. Also the dry weight of the boat is between 2600-2800 lbs and max capacity is 1200 lbs(which I will be close to most of the time). Thanks.

 

[steelespike]

Re: Is a 15 pitch prop too low

what is the present max rpm and speed?

 

[sschefer]

Re: Is a 15 pitch prop too low

If you're running a 18 now, I suspect that its the manufacturers recommended prop at sea level. With a 4 blade at sea level you should drop 1 inch of pitch and be running a 17. At 4000 feet you should drop at least another inch because your engine won't make as much horsepower as it would a sea level. I believe your prop should be a 15 or 16. If you can find a 16 that's what I would go with. If not, a 15 will probably be o.k.

 

[swirly]

Re: Is a 15 pitch prop too low

I'm not sure on the current max speed/rpm. I didn't pay close attention to it last year and I never topped it out. I'll be dropping it in for the first time this year in the next week or two and will check now that I'm aware of what to look for. I do currently have an aluminum 4 blade 14.5 x 17 that I'll compare it to.