Prop suggestions needed....

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whitetailhntr

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I have a 1989 15hp johnson that will need a prop soon. Is there any benefit going to a four blade prop? What's a good brand to go with? I'm thinking about going with an aluminum one since the stainless steel props are pretty pricey. Any suggestions would be great.
 
Unless you know what RPM & speed you're turning at WOT with the current prop it is nothing more than a guess what works and what doesn't.

You can do some reading about props here:

https://www.veradoclub.com/index.php?topic=137.0

https://www.rbbi.com/folders/prop/propcalc.htm

https://turningpointpropellers.com/
 
As mentioned, a tiny tach or off brand version is the ONLY way to go about buying a new prop (unless you decide to just buy and exact replacment) I just went through this on my 1991 Evinrude 15. I was turning a stock 9.5x10" aluminum prop with no clue of WOT RPM. My stock prop rpms were 6330 at 23 mph and the 9" prop was running 6600 at 21 mph. I did however order a solas 9.25x9" for when I have an extra guy in the boat.
 
All you guys with "Whitetail" and "Bowhunting" in your user names makes me want to go stretch a string.

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Yes there is an advantage to the 4th blade. But it all has to do with what YOU want out of the boat. If you won't miss about 1.5 to 2 mph, and you like to get on plane faster, hold plane at a lower RPM, run smoother, and if you run the motor high on the transom in choppy waters, you'll like the 4 blade.

I don't race, rarely do I ever go wide open throttle. But I like the faster plane time and smoother running. Holds plane about 200 RPM slower than the 3 blade stainless, and it's 1" less pitch (SS 3 blade 11", AL 4 blade solas 10"). Speed is roughly 2 mph less with the 4 blade. SS would get about 1mph back (verfied-friend has a 10" SS Solas 4 blade that I borrowed for giggles).

If you decide you want one, drop about an inch of pitch from what you already have-if what you currently run is close to optimal. For instance, if your motor's max RPM is 6000 and you're running 5900-6100 RPM already with a 3 blade 10", if you go 4 blade, you'll want to drop back to a 9" pitch for best results.

I also had a 4 blade Solas AL prop on my old 9.9-and loved it on that one as well. The factory 9" pitch 3 blade would not plane the 1432 boat. I dinged it up pretty good and went to buy a prop, and they had an 8" 4 blade in stock, and discounted...so I tried it. And loved it. Sold it with that prop on it. In that case, the 4 blade was faster because it would actually plane the hull.
 
in a given pitch say a 9 .. a 4 blade will give more lift to get on plane, ie" a midrange prop .... a 3 blade of the same witch will give a tad more top end .... also one thing t think about is how much reverse thrust do ya need, my 4 blade has a hard time gettin me off the trailer where as the 3 blade it flys right off.
 

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