New Engine, new Prop?

[Mike Robinson]

Hello All

We have a 19' welded aluminum boat, the weight is unknown but it was heavily built for commercial use and has a cabin but no bunks, galley or head. We have recently replaced the outboard on it. We primarily use the boat for fishing, we usually run about 1 1/2 hours to the fishing grounds then drift or troll with the kicker (a 9.9 Yamaha).

Previously it had a '94 Johnson 150 and we replaced it with a brand new 2007 ETEC Evinrude 150 with a gear ratio of 1.85:1. We are using the same prop that we used with the Johnson, it is a "Turning Point" 14 1/4" by 15" three blade stainless.

Now that we have a couple of hours on the Evinrude I find that I can get 35 knots (GPS) at 5800 RPMs WOT. Hole shot seems fine.

I am wondering if the outboard has a rev limiter on it and if I should go up a couple of inches in pitch.

Thanks for your help

 

[twisterlodge]

Re: New Engine, new Prop?

i wonder how a 17 or even 19 inch prop would perform on that rig,... you would loose a few rpm but gian alot of speed depending on the loads you were hauling

 

[trendsetter240]

Re: New Engine, new Prop?

Hey Mike,

Glad to see you are enjoying your new motor. And yes, I am jealous

WOT spec for your motor is 4850-5850 so you are about perfect on the RPM front. Your speed, if it is Knots and not MPH is also about perfect with a 10% slip.

You would be hard pressed to find a better prop than what you have now.

If your speed is in MPH then you can do better. Please let us know.


Cheers

 

[Mike Robinson]

Re: New Engine, new Prop?

Hi Trendsetter

Yes that speed is in knots. I was wondering if the outboard has some kind of rpm limiter or that truly was WOT. Sounds like from your calculations all is good.

Thanks

 

[Dhadley]

Re: New Engine, new Prop?

The folks at BRP may or may not admit it - depending on who you talk to - but once your motor comes out of break in mode you will gain some top rpm. Don't do anything until then. It will come out of break in ater you get about 20 hours on the motor. Those hours have to be under a load above a certain rpm. Idle time does not count.

Yes, your motor has a rev limiter but you're not close yet.

 

[Mike Robinson]

Re: New Engine, new Prop?

Thanks Dhadley! I will wait.