Prop selection for Yamaha 115 and a Pontoon

[WaterDR]

I just recently stuck a stainless prop on a pontoon and curious to finhd out from the prop gods if my performance makes sense and if I have the correct pitch.

With a 15p alum prop and a light load, the toon would run (in my sig) 28 mph or so on gps and turn 6200 rpms.

I upgraded to a stainless 13p and ran it today. I am seeing the same top speed, but it pulls a lot stronger and the rpms run up to 6400. This was with practically no fuel and just me. I was not hitting the rev limiter.

Does this seem like the correct prop, or should I be looking for a 14p. All the yami techs are telling me that the rpms are fine, just as long as I am not bouncing of the limiter.

 

[jestor68]

Re: Prop selection for Yamaha 115 and a Pontoon

Since you were 200 rpm over the factory recommended rev limit with the 15P prop, I have to wonder why you didn't put a SS 15 on there.

That might have brought you down to right at 6000 rpm rev limit and produced a little speed. Your Yami tech doesn't sound too smart. The rev limiter is there to keep the motor from exploding; not as an indicator of maximum rpm.

 

[WaterDR]

Re: Prop selection for Yamaha 115 and a Pontoon

Because everyone, including Yamaha, told me to drop two pitches with a SS prop from what I was running. As to the Yamaha tech, one of them happened to be a factory rep who also added that the analog tachs are not always accurate either.

Now as I recall, the manual states that the limiter is set at 6200 rpms, so there really should be no way that I am running 6400.

I guess I need to find a way to email Yamaha to be sure.

 

[jestor68]

Re: Prop selection for Yamaha 115 and a Pontoon

My response to your Feb 7 thread made sense. I'll stick with that one.

Running past the HP peak is a waste of time and performance. If these people were professional and questioned the accuracy of the tachometer that indicated you were over speeding your new motor; they should verify the rpm or reprint the factory manual to indicate the rpm limit is now 5000-6400 rpm. Overspeeding the motor usually voids the warranty. Good luck.

 

[WaterDR]

Re: Prop selection for Yamaha 115 and a Pontoon

If the limiter is set at 6200, how could it rev past that? I am questioning the accuracy of the tach. The motor has not been modified. Something is not adding up.

 

[jestor68]

Re: Prop selection for Yamaha 115 and a Pontoon

Because everyone, including Yamaha, told me to drop two pitches with a SS prop from what I was running. As to the Yamaha tech, one of them happened to be a factory rep who also added that the analog tachs are not always accurate either.

Now as I recall, the manual states that the limiter is set at 6200 rpms, so there really should be no way that I am running 6400.

I guess I need to find a way to email Yamaha to be sure.

You need to verify the rpm. The dealer should be able to do that. The RPM limiter should kick in at the appropriate rpm(+/- some tolerance), if it's functioning.

These new motors have black boxes that record operational parameters(including rpm levels and percentages at that rpm). They record all the time, like forever. If three years down the road, it has a possible warranty problem, the first thing they'll do is read the data stored there.

Imagine this happening: Next year, your motor fails. You take it in for warranty repair. They read the data stored in the "box" and see that the motor has been operating X hours at rpm levels over the factory recommended limit. You might well have a problem getting the warranty to cover it, since over speeding the rpm is considered "abuse".

I wonder if those techs/reps would have been willing to put their advice in writing. I am doing that right now. Do not operate your motor over the factory recommended rpm limit.....EVER.

If you question the accuracy of the rpm reading, get it checked. Little Brother is recording.

 

[WaterDR]

Re: Prop selection for Yamaha 115 and a Pontoon

I have found a tech support number for Yamaha. I will call them tomorrow and let you know what I find.

 

[jestor68]

Re: Prop selection for Yamaha 115 and a Pontoon

If the limiter is set at 6200, how could it rev past that? I am questioning the accuracy of the tach. The motor has not been modified. Something is not adding up.

I thought Yamahas had that info center thing with a digital tachometer. (?)

 

[jestor68]

Re: Prop selection for Yamaha 115 and a Pontoon

I have found a tech support number for Yamaha. I will call them tomorrow and let you know what I find.

The dealer will have a "shop tach" he can use to check it.

It may be possible for him to tap into the ECM/EMM(whatever Yamaha calls it) and read the highest rpm recorded.

Don't let them tell you not to worry about it. You cannot select the best prop without accurate rpm readings. You have a new motor/boat. The instruments(including the tach) are under warranty too. If the tach isn't working right, they should replace it.

 

[WaterDR]

Re: Prop selection for Yamaha 115 and a Pontoon

I spoke to Yamaha this AM. The motor is designed to hit the limiter at 6250 and they recomend running at 6,000 as you had stated which allows some room for error especially if the prop should come out of the water, etc... I was also told that my tach is probably reading a little high and that this was not unusual. He also told me that if I were hitting the limiter, I would not really know it. The RPMs would just stop.

He suggested re-testing with more of a typical load (fuel and people), but I suspect I need more pitch.