A Little Prop Help

[pilot4net]

I have been working with my boat manufacturer on getting the right prop for my boat. Originally I had a 13.25x19 three blade on a four stroke yamaha 115. The recommended rpm range, as per a Yamaha tech that I spoke to on the phone, is as close to but not over 6000 rpms. The WOT rpms at the optimum trim would only reach 5250 rpms. The tech said let's try a 13.25x17 four blade. I put the new four blade on and tested it out and got about 6200 rpms at WOT; too high. So I am wondering, is it possible to get an 18" pitch prop? I haven't seen any online, maybe I just haven't looked enough; I don't know. To my rather inexperienced reasoning, an 18" pitch might just be the happy medium I am searching for. Please, everyone that can give me some advice, please do so and all your suggestions will be greatly appreciated. Thanks.

 

[TilliamWe]

Re: A Little Prop Help

Not sure about an 18 pitch prop that fits your engine, but yes, 18 pitch props are out there.<br />According to trailerboats magazine's July issue, there is a prop called the Performance 4BL from Yamaha with the large hub that comes in pitch size from 18 thru 26. It's the only 4 blade they have.

 

[ufm82]

Re: A Little Prop Help

You can have a prop re-pitched as well. If you like the prop and it performs well for you now, you may be able to simply drop it at a prop shop and have them re-pitch it to an 18. Shouldn't be any more than $100 and it can save the endless search for "the right prop". <br /><br /> It's an option many people don't know/think about. You could have them add some cup too- that should bring you down about 100 RPM. <br /><br />UFM82

 

[iboater]

Re: A Little Prop Help

you shouldn't see a 1000 rpm difference from a 19p to a 17p in any situation really. I would get with your tech again and figure out what is up.

 

[shep70057]

Re: A Little Prop Help

Iboater... he also went from a 3 blade to a 4 blade. I agree with you that the difference is just too great. I would have expected a 2-300 rpm difference.