# Prop Pitch???



## aragorn1 (Mar 12, 2013)

If I want to increase my top end speed and currently running a 24 pitch prop, should I go with a 26 pitch or 22pitch?  Not sure how the numbers work in relation to more top end speed.


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## 8pointduck (Mar 12, 2013)

Higher pitch for speed lower pitch for torque.


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## Terribleted (Mar 12, 2013)

The general best compromise is to have a prop that runs the engine at its max sustained rpm with the throttle wide open. 1 degree pitch change = roughly 250 rpm change on most motors. Add a degree and loose 250 rpm or drop a degree and gain 250.


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## wwright713 (Mar 12, 2013)

Before you purchase another prop play with the trim while running to find a good motor angle and see what that does for you


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## aragorn1 (Mar 13, 2013)

8pointduck said:


> Higher pitch for speed lower pitch for torque.



The general best compromise is to have a prop that runs the engine at its max sustained rpm with the throttle wide open. 1 degree pitch change = roughly 250 rpm change on most motors. Add a degree and loose 250 rpm or drop a degree and gain 250. 

These appear to contradict themselves, can someone explain which is right?  If I have a 24, would a 26 or 22 give me more speed? Any help is always appreciated!!!!!


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## aragorn1 (Mar 13, 2013)

I know cars better than boats.  For example a 4.11(take off) rear end is a lower gear than a 2.73(top end).


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## Nuttin Better (Mar 13, 2013)

A 26 pitch prop will be faster than a 24 pitch but it may slow down the RPM of your motor some because it will take more Horse Power to turn the 26 rather than the 24. The pitch of a prop equates to the distance a prop will move the boat with one full revolution of the prop.


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## Backlasher82 (Mar 13, 2013)

aragorn1 said:


> The general best compromise is to have a prop that runs the engine at its max sustained rpm with the throttle wide open. 1 degree pitch change = roughly 250 rpm change on most motors. Add a degree and loose 250 rpm or drop a degree and gain 250.
> 
> These appear to contradict themselves, can someone explain which is right?  If I have a 24, would a 26 or 22 give me more speed? Any help is always appreciated!!!!!



A 26 pitch prop would give more top speed, 22 would give more low end pull. 

Prop pitch is the theoretical distance it would move forward in one turn. A 26 pitch would move 26" in one turn. Of course that is theoretical because there is slippage in water. 

To compare with car gearing, 26 pitch would be your 2.73 rear end for top speed but slow acceleration, 19 pitch would be your 4.11 with great acceleration out of the hole but top speed would suffer and your motor would be screaming it's guts out wide open.

Ted was right about the 250 rpm change per pitch. If you go from 24 to 26 pitch, rpm will drop about 500 because it's geared higher. Go from 24 to 22 pitch and rpms will increase about 500.  

 What rpm you're turning now with your 24 when wide open and trimmed will give you an idea of the correct prop. Check the manual on your outboard for their rpm recommendations, different motors have different specs, and make sure you aren't over revving at WOT. 

BBC has good info on boat set ups, but you can get a good idea of what will work by looking at what rpm you're turning with your 24p and use the 250 rpm rule of thumb.


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## Gunny146 (Mar 13, 2013)

PM sent


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## Eugene Stinson (Mar 13, 2013)

Are you looking for general information or are you trying to get more out of your setup? If you are trying to tweak your ride, what boat and motor do you have.


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## 06 SB (Mar 13, 2013)

It really depends on the boat/motor/prop combination.  What is your RPM at wide open throttle (WOT) and trimmed up for best speed?  What is the max recommended range of the motor you have?  We really NEED those two questions answered before better advice can be given. 

For example, If your boat is running at WOT and your motor RPM is 5600 and the max recommended RPM is 5700 with your 24P prop you are set up as good as your going to get.  Changing the prop to a 26P without changing something else will result is little if any gain in top speed but you will have a slow holeshot.  The reason for this is that while the prop is going a longer distance per revolution, your RPMs are 300-500 lower than before.  

In order to gain speed on a properly set up boat, you need to add a jackplate so that you can raise the motor in order to use a higher pitched prop AND maintain near max RPM.  If you are using an aluminum prop, a stainless will be a change for the positive too.

06


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## Stumpthumper (Mar 13, 2013)

Others have started to touch on this but before you are really going to get anywhere here, you need to do some preliminary work for us. Load the boat how you would under normal conditions and head to the lake. To really help you out we need the following info:
1. GPS speed at WOT
2. RPM's at WOT
3. Water Pressure at WOT
4. Center Prop shaft to pad measurement
5. It appears you have a jack plate from your avitar (I think!) what size is it?
Look like your running a Javelin with a Johnson, but years and models/size would be good info too! To really get your boat running to it's fullest, it takes some leg work!  Like Backlasher said, BBC has a great section for boat set up/props too. The more info you can provide the better. Random guess based of the info you gave though, I would say a 25 raker would the prop I would try before jumping to a 26.  That is a significant jump in size!


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## TroyBoy30 (Mar 13, 2013)

get all the specs listed above and post them in the set up section of bass boat central.  you can also get great starting point advice by going to the specific boat brand section and asking.


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## scott44 (Mar 13, 2013)

Gotta have a tach before you really know what to do.Plus load the boat the boat the way its most commonly used.


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## aragorn1 (Mar 13, 2013)

Thanks for all the info guys!!!!  My boat is a Stratos 273 with a Johnson Fast Strike 150 mounted on a manual jack plate.  My prop is a 24 pitch Raker.  I need to come up with some numbers so you guys will be able to help me further.  This Saturday I am up in the rotation at work, so it my be a week or two from then before I take the boat out again.


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## Coon Krazy (Mar 13, 2013)

Wouldnt lower rpms Slow the boat?? I Have the same problem...Im running a 22 pitchraker on my 120 Johnson and not even close To maxing the rpms. For some reason I keep thinking Higher rpms would make the boat Have better top end


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## Eugene Stinson (Mar 13, 2013)

For your boat you need to start with the center of the prop shaft 3 1/2 inches below the pad. Jack the motor up with the jack plate 1/8 inch and make run WOT noting GPS speed. As you go up 1/8 at a time you will see some increases in top end speed. When you jack it up twice and notice no increase in speed, go back down one and you are just about right. Run it again and make a medium turn left or right and see if the prop starts sucking air and loses a lot of speed. If this happens the motor is too high. Also watch you water pressure. Don’t let it go below (15 lbs. imo, I was told 12.5lbs) If it does you are too high. 
I have a Stratos 284 with a 150 Johnson fast strike. This was the advice given to me by J. Lively a Stratos boat tech. A Johnson 150 fast strike is supposed to run from 5000 to 5500 rpms. The 24 pitch runs on my boat at 5100 to 5200. Water pressure around 30 lbs. 24 pitch is right. A 23 pitch 4-blade can be used in the summer (5300) but will over rev in the winter( up to 5500rpms). A 25 pitch 4-blade will give you about the same result as the 24 pitch 3-blade. I have all of these props if you want to try one out. My boat with nothing in it and 1/4 tank of gas will run 64. Tx ready with just me in it runs 61.5 with 2 people 60mph. Hope this help you a little.


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