# Quick Prop Question For you Experts



## Kustrud (Jan 5, 2015)

1996 Evinrude 25 HP - any idea the prop size/pitch that comes on these things??


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## Boat2fast (Jan 5, 2015)

What's the model number?


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## Kustrud (Jan 5, 2015)

E25REDA - thanks for the help!


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## SumDumGuy (Jan 6, 2015)

I see this:

Part Number: 0387320
Description: PROPELLER 11 1/4 X 7 AL

{not an expert, but answered anyway}


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## Charger25 (Jan 6, 2015)

I'm running a 10x13 on mine


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## Siguz (Jan 6, 2015)

10 x 12 on mine.
achieves max RPM when it's just me in the boat.


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## Kustrud (Jan 6, 2015)

Interesting - everyone is using a higher pitch than I was thinking for some reason. Boat is a 648 War Eagle, I think it weighs about 550 lbs. 1 batt, gas tank, me (230), 1 - 2 buddies......what should I go with? The one on there is all dinged up. Any way to determine the size/pitch that is on there?

Currently - With me and a guy about my size we hit 23 MPH, by myself 26 MPH - boat was trimmed too far down though too.....


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## Boat2fast (Jan 8, 2015)

The standard prop installed on your model is the:
0175191 PROPELLER 10 X 13 AL (Std. 20,25)

Look on ebay for a really nice one. I tend to avoid rebuilt props. After you buy or borrow a real nice one, check full throttle rpm under light-load conditions. You want to be up near the top of the recommended operating range(4500-5500rpm)....under light-load conditions. 

RPM will drop off as you load down the boat and speed drops. If the rpm remains in the proper range under all loads, you're all set. 

If it drops down too far as you load down the boat, then you need an 11pitch to bring the rpm back up into proper range. 

For example: My MV1648 has a Johnson 40hp tiller. Normally I run a 19P stainless prop for running fast and light. When it's time to add passengers or pull a tube, I change to my spare prop, a 17P aluminum. It is very rare that I ever have to go looking for my 15P. (passengers _and_ tubes)

Running the engine above the recommended full throttle operating range accelerates wear and reduces power. 
Running below the range, at full throttle, over-loads/over-heats the engine...and loses power. 
That engine is pretty happy around 5500 rpm at full throttle.


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## Kustrud (Jan 13, 2015)

Gotcha! So if I want to keep whats on there just look for a 10 x 13 and I should be all set?

Judging by sound - seems to be in the proper range......


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## Boat2fast (Jan 14, 2015)

No, not what I was thinking. 

You are trying to pick a starting point. Finding the right prop is a process. It's possible to find the right one the first time. Certainly you don't want to end up with two or three wrong ones before finding the one or two right ones. Take it from someone with shelves full of mistakes. It's a really cool collection of props...but it's just too many props.

Another mistake I made for years was trusting my 'ear' on rpm. A TinyTach is a great tool. There are other tools too. MAC Tools sells a SmartTach that reads the sparks through an antenna. You don't even have to hook up any wires at all. I used one of these long enough to love the idea, but hate the cheapy tool itself. The meter was cheaply built and delicate...not happy in a tin boat at speed. I went back to the tiny tach, you have to take a minute or two and wire it in before you go out. Works real good _if you read and follow directions_.

Where you want to wind up: 
ONE good fast prop for light to moderate loads, preferably stainless-steel. (my opinion)
A SPARE prop, one size smaller, that you can pop on there for any heavy load condition...or if you wreck your good prop. Aluminum is fine here.

If you are on a budget, and who isn't these days, it's best to borrow a prop for testing purposes. (If you live near MA/CT stop in around Spring) Take a run with the tach using a prop in perfect condition. Beat up props are a waste of time, fuel, and power.

Try a 13P maybe first. Your first try tells you which direction to go in next: 
If the boat is sluggish and doesn't come up to 5500rpm, or so, Then look for an 11P. Return the 13P or put it on your shelf. 
If the thing screams out of the hole and starts bumping off the rev limiter(around 6100) at top speed, then you want to try a 15P. The 13P can be your SPARE.
Remember to do your _initial_ testing with LIGHTEST possible load. You, boat, motor, tank. 

You CAN use a prop that is too small. It makes a good spare and you can always throttle back. It will carry a bigger load. Its easier to sell.
You CANNOT use a prop that is too big. It will make the boat a slug out of the hole. It will over-load/over-heat the engine at speed. It's also harder to sell, works on fewer rigs. It goes on the shelf.

The factory original-equipment prop is always the most widely used prop and therefor it is the easiest to resell if it's not right for your rig. 
0175191 PROPELLER 10 X 13 AL (Std. 20,25)


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## Kustrud (Jan 24, 2015)

So to bring this back up, I haven't tried any new props, but I looked at my prop today and it's a 10 x 15 stamped on the side of it. If I try a 10 x 13 will I lose any speed or if the motor revs higher would it even out as far as speed and just be easier on the motor? No tach so kind of guessing....


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## Kustrud (Jan 24, 2015)

So to bring this back up, I haven't tried any new props, but I looked at my prop today and it's a 10 x 15 stamped on the side of it. If I try a 10 x 13 will I lose any speed or if the motor revs higher would it even out as far as speed and just be easier on the motor? No tach so kind of guessing....


UPDATE: Bought a 10x13 AL prop today, looks so nice compared to the old one! Put it on and should be able to take the boat out tomorrow. Hoping for better performance all around. Will post results.


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## Boat2fast (Jan 25, 2015)

Here's a good source of prop information.


https://www.miwheel.com/resources/faq/


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## Kustrud (Jan 25, 2015)

Good link, thanks!

Took the boat out, what a difference!

I was by myself so not the best test but the thing jumps out of the hole and I didn't lose any top speed. Motor revs a little higher I can tell my ear and I is much much quicker. I think with two or more people the performance will be day and night. I'm gonna stick with the 10 x 13 and I'll check it with a tac here soon. 

Thanks for all the help!


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