# 2007 Johnson 15hp 2stroke prop help



## jonathantaylor (Mar 18, 2010)

My boat is turning about 6100 rpm w/ me and a fishing buddy on the tiny tac. Right now I am running a 10x11 piranha composite prop. I would like to go to 9 1/4 x 12 alum and see where that takes me. I have tried a 10 x 13 and that was too much prop (4900rpm). I can't find any alum props pitched more that 11 for my motor. Where should I look and is a 9 1/4 x 12 sound about right? Also I would like to go to ss prop but what to make sure the size/pitch is right before I drop that kind of money in a prop. Thanks


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## DuckNut (Apr 3, 2009)

Take your aluminum prop to a prop shop and for about $65 they can make it anything you want it to be. After you get it right go to evilbay buy another for $20 and have a spare made.


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## jonathantaylor (Mar 18, 2010)

We dont have a prop shop here. I fish in small rivers in south east georgia and in the summer they get very shallow and you hit alot of stuff. The tech at the boat shop here told me I shouldn't run a stainless prop because i would likley damage the lower unit. Are the hubs in props for smaller boats not designed to spin before lower unit damage? I am trying to decide between ss and alum. Thanks


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## Flyline (Mar 3, 2008)

U know composite propeller spins faster than aluminum propeller because of the weight and flexibility?

Say u have 10x11p composite propeller spins at 6100 rpm. 

If u get a aluminum propeller 10 x 11p and u will be looking at 5500 rpm average.

I'm thinking 9.25 x 12p aluminum will spin about the same.

10 x 13p aluminum = 4900 RPM as you stated.

10 x 12P = 5200 RPM

10 x 11p = 5400 RPM

9.25 x 11p = 5700 RPM

9.25 x 12P = 5500 RPM

That's the best guessimate by increase 1" pitch will lost 200 RPM or decrease 1" pitch will gain 200 RPM.

My 2 cents...


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## mark_gardner (Mar 18, 2009)

i do know one thing :-? i have busted up many a aluminum prop but never busted a lower unit using a ss prop and i've hit more stuff than the average guy


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## jonathantaylor (Mar 18, 2010)

Thats kinda what I was thinkin. I think I'm gonna go with powertechs class a srt3 9.5 X 11. Anybody got any sugestions on where to order it from?


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## Flyline (Mar 3, 2008)

> Thats kinda what I was thinkin. I think I'm gonna go with powertechs class a srt3 9.5 X 11. Anybody got any sugestions on where to order it from?



Call Ron at theskiffshop.com

The 11" pitch SRT model sounds deep......

Get a 10" pitch stainless steel if u get a SRT model....trust me on this.

I ordered a 9.25 x 10" pitch SRT S.S propeller with no cup for my merc 15hp 2-stroke.

I should have went to 9.25 x 9" pitch with cup but it'll be fine.


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## Yoreese (Oct 15, 2009)

I have a SWA3 10" on my 9.9 Evinrude and it runs great!


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## Flyline (Mar 3, 2008)

> I have a SWA3 10" on my 9.9 Evinrude and it runs great!


SWA has a smaller blade which is spin faster than SRT model. SRT model has little bit wider blade than swa model.


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## Yoreese (Oct 15, 2009)

> > I have a SWA3 10" on my 9.9 Evinrude and it runs great!
> 
> 
> SWA has a smaller blade which is spin faster than SRT model.  SRT model has little bit wider blade than swa model.


Wasn't sure what the actual difference was, thought it might be cup in the blades.


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## Flyline (Mar 3, 2008)

*The SRT model has wider far blades for designed heavy load and 4-stroke engine*










*The SWA model has a smaller blade design for high speed light load application.*











*Look closer and you will see the difference of the propeller *


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## Yoreese (Oct 15, 2009)

Cool! I just need a few more ponies to get the MPH up! ;D


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## Flyline (Mar 3, 2008)

> Cool! I just need a few more ponies to get the MPH up! ;D



What's the max RPM are u running?

Tune your 9.9hp to 15hp by swap bigger carb.....


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## Yoreese (Oct 15, 2009)

> > Cool!  I just need a few more ponies to get the MPH up! ;D
> 
> 
> 
> ...


Don't have a clue what RPM but it sounds and feels wound out good with the 10 pitch. I like the holeshot so don't think more pitch without more HP is going to fix my issues. The boat performs great just runs out of juice on top. I'm used to the power of a 25HP but don't think that would be a good idea on the Gladesmen!!!


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