Pontoon Boat & Deck Boat Forum

I need some help with a prop question. I have a 26' G3 tritoon with lifting strakes and a Yamaha 225 four stroke. The prop that the marina where I bought the boat has the following numbers on it ( 19-M 13 3/4) I assume that it is 13 3/4" in diameter and the pitch is 19. The boat runs good now 35 mph @ 5500 rpm, but I still have tons of throddle left. My question is simply what would you guys recommend? Is a larger diameter prop possiable on this outboard and would it help, or should I try to stay with the same size and get more pitch?

You ideas are greatly appreciated
Thanks
JD

I'm thinkin more pitch bro. sounds like your gettin an awful lot of slippage

Is the current prop stainless? Surprised you got a lot of throttle left at 5500 rpm. Seems like you should be getting 40 or better with the right prop. Depending on the weight of the boat. I love the enertia on my boat. Only problem they are not cheap. Thinking the 19p should be ballpark.
http://sites.mercurymarine.com/pls/port ... EASE_0.PDF


http://forums.iboats.com/showthread.php?t=162494

Seems like they were designed for off shore (center console) type boats, but they do really well on toons.

doc

sounds like you've got the wrong pitch. read the yamaha manual. it will tell you the acceptable
RPM range at WOT, wide open throttle. prop to achieve that. don't over-rev the engine with
the wrong prop pitch, you may regret it.

hey guys, thanks for the resposes, I think I need more pitch as well.

When looking at other props it seams that there are alot of options in the 14 1/4 diameter. My current prop is 13 3/4. Am I stuck buying a 13 3/4 or can I use a 14 1/4 and if I can how will it affect my pitch choices.

Messing with diameter is a pain. I'd stick with the pitch unless you're getting a lot of blowout or cavitation. For every inch of pitch you increase expect to lose about 200 RPM at wide open throttle (WOT). You want your RPM to be at your engines maximum rated RPM with a light load on board at WOT. Good luck.

Ok thats what i was thinking... what exactly is blowout?? Right now I can even push the thoddle all the way forward becasue the rpms jump up past 6000 heading for 7000 real quick... I believe wide open throddle for my outboard (f225) is 5500 rpms. The prop im using the dealer put on it is stainless steel 19m 13 3/4. Would going to a 21 pitch prop be a safe choice?

Here's a couple of Performance Bulletin Results for G3 Boats that may be helpful to you. They have this one listed as 6100 rps. so it must still be in the safe max. rpm area. http://www.yamaha-motor.com/assets/prod ... 225tlr.pdf Then they have this test maxing out at 5500 with a bit more speed at lower rpm's http://www.yamaha-motor.com/assets/prod ... 225tlr.pdf And you can review some more results here if you care to http://www.yamaha-motor.com/outboard/pr ... s=outboard

your engine shouldn't be able to reach above it's redline in that it's got a rev limiter which cuts spark when max rev's is hit. When your engine rev's up fast as you state does the prop seem to lose grip. That could be cavitation. If your in a turn and your engine rev's up and the prop again loses grip that's blowout. You may have a engine mount issue. Possibly your engine is not mounted low enough. I'd work with the prop first before trouble shooting further.

was thinking the same about the rev limiter, or possibility of a bad tach reading. Not really saying the tach is bad but seems like it would have hit the rev limit before hitting 7k. I have a smart gauge an it has a tach function among other things, but I noticed there is a difference in the two reading, can't recall how much but would be more inclined to believe the digital smart gauge over the factory tach.
doc

Bamby wrote:Here's a couple of Performance Bulletin Results for G3 Boats that may be helpful to you. They have this one listed as 6100 rps. so it must still be in the safe max. rpm area. http://www.yamaha-motor.com/assets/prod ... 225tlr.pdf Then they have this test maxing out at 5500 with a bit more speed at lower rpm's http://www.yamaha-motor.com/assets/prod ... 225tlr.pdf And you can review some more results here if you care to http://www.yamaha-motor.com/outboard/pr ... s=outboard

Thanks guys for all your impute, Bamby the performance links were particularly helpful as they are my exact boat and engine, show completely different props and performance ranges. I will swap props at my 10 hour service and up date you guys on any performance changes after that.

As far as rev limiter, it probably works because anytime I push the throttle and the Rpm head past 6000 rpm, I pull it back as I dont want any damage. I have never achieved WOT because of this. Thanks again for all the help..

Update

I had the prop swapped out at my 10 hr service. Ended up going with a 2" larger diameter prop with the same pitch. The new prop is a saltwater series so it is a little more aggressive. The boat got 40mph on gps with a little chop and wind. 37 loaded with 6 adults. Thanks for all the imput
JD