Fast Prop Selection

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Dank Xploidz

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Nov 4, 2008
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I have a 2005 yamaha 2 stroke 25 hp, whats the fastest prop I can put on it? would it be a 10 1/8 with a 15 pitch?
 
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Dank Xploidz

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Re: Fast Prop Selection

I want more top end speed, I am normally the only person in my boat.
Which is better fir top end? 4 blade or 3 blade?
 
Bondo

Bondo

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Re: Fast Prop Selection

Which is better fir top end?
Click to expand...

Ayuh,...

The one that allows your motor to run at the manufacturer's recommended RPMs at WOT.....
 
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steelespike

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Re: Fast Prop Selection

First of all we need all the particulars of your boat and setup.
need present prop and max rpm and speed.Motor needs to operate within its recomended rpm range.A tinytach is reasonable,easy to hook up and will operate on any similar motor without regard to stator poles.A gps will get your speed.
 
Randybeall

Randybeall

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Re: Fast Prop Selection

Go back to the first screen of Props. You will see a post that says "Read this First", please read it and answer the questions for us. With out that information you will be given wrong answers or at best wild guesses. Most of these people will not waste their time without something to go on. Give us the information and we will do our best to calculate and give you a helpful answer.
 
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Dank Xploidz

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Re: Fast Prop Selection

i have a 9 7/8 with an 11 pitch. Thats the stock prop. it runs 32 with the gps.
 
Silvertip

Silvertip

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Re: Fast Prop Selection

Still no help since you don't have an rpm number at wide open throttle. That's what determines whether you have the right prop.
 
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steelespike

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Re: Fast Prop Selection

steelespike said:
First of all we need all the particulars of your boat and setup.
need present prop and max rpm and speed.Motor needs to operate within its recomended rpm range.A tinytach is reasonable,easy to hook up and will operate on any similar motor without regard to stator poles.A gps will get your speed.
Click to expand...
We need this for your motor health and best performance.
I will say that 32 is close to your max speed with a 25.
Without the rpm no way to know where to go from here.
There are some things you can do that are free.
 
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Dank Xploidz

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Re: Fast Prop Selection

I was running around 5500 rpms, the manual says 5000-6000 rpm range. so what is a fast prop for it?
 
Silvertip

Silvertip

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Re: Fast Prop Selection

Thats what tachometers are for. Regardless what prop you install, if the engine runs at or very near the top of the manufacturers WOT rpm band, speed is what you get with that prop. Installing a prop with more pitch will likely slow you down because the engine does not have enough power to twist more pitch.
 
Randybeall

Randybeall

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Re: Fast Prop Selection

You have said it correctly, a stock prop can be quicker than a "performance" prop. A boat and motor is like a dynometer measuring horsepower. When you get all the elements right the prop will transfer all the horsepower of the engine to the water most efficently and use up all the horsepower achieving top rpm. Too shallow of a pitch will allow the engine to overspeed and not transfer all the power, too steep of a pitch will bog the motor down and not allow it to reach peak power. It is a fine balance. You can sometimes change to a Stainless Steel prop and gain efficency through the thinner stiffer material and gain a little speed but 25 horse power is only 25 horse power. We are not talking drag boat here! If your achieveing 5500 rpm and not overunning running at wide open throttle you have reached the best your going to get with out very small adjustments which might give you one or two miles per hour. Try raising the engine 1 inch and see if you gain anything. Make sure you dont loose water flow and watch out for venitlation (prop slipping in the water).
 
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Dank Xploidz

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Re: Fast Prop Selection

Alright Thanks,
The boat its on is a 94 Duracraft 1542, with approx. 100 extra weight, and just me so.. What do you think? Maybe a 10 3/8 by 13? The prop on there now is a 9 1/8 by 11.
 
Bondo

Bondo

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Re: Fast Prop Selection

I was running around 5500 rpms, the manual says 5000-6000 rpm range. so what is a fast prop for it?
What do you think? Maybe a 10 3/8 by 13? The prop on there now is a 9 1/8 by 11.
Click to expand...

Ayuh,... Sure,.. If you want to go Slower,+ Probably Blow Up your motor....

The motor is just pulling Max rpms at WOT Now....
Propping it Up, is going to drop the rpms,+ Overload the motor....
 
QC

QC

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Mar 22, 2005
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22,783
Re: Fast Prop Selection

Your suggestion above may be slightly faster, may be slightly slower, may totally suck. Fastest top speed are usually 3 blades and stainless . . . but we're still only talking 1 - 2 MPH, and no guarantees really with whatever you do. Props are part technical with a decent chunk of voodoo. Personally, like others have indicated, I think you're pretty good right where you are ;)
 
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steelespike

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Apr 26, 2002
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Re: Fast Prop Selection

So how did you suddenly come up witrh this rpm?
If your looking for more speed check out the Hustler props probably in the same pitch.Hustler is said to deliver ss performance at al prices.
The little I've read they seem to improve overall performance.
Again changing props without a tach is a gamble both for performance and motor health.
 
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Dank Xploidz

Seaman Apprentice
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Nov 4, 2008
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Re: Fast Prop Selection

Where can I find a portable tachometer? do i have to buy one? or is there some place that lends them?
 
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steelespike

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19,069
Re: Fast Prop Selection

As I understand it the Tinytach is about $40 It attaches to a plug wire
easily added and removed.And again will work on any similar motor.
Check with the Tinytach people.I know someone here has one perhaps they will chime in.
 
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