# Prop help



## Treyconner05 (May 26, 2021)

I have 2 props I can use right now. Trimmed out and jacked up, my 9P gets me over-revving with 2 people and a full load, and my 11P SS gets me under-revving at 5400 RPM with just me in the boat. My rpms are supposed to be between 5800 and 6200. What should I do?


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## NealXB2003 (Jun 8, 2020)

Both similar in design, construction, and materials? All else being equal, 1" of pitch is usually good for 200 rpms. But aluminum will spin up more than stainless because of flex, 4 blade will spin less than 3 because of the drag, e.t.c.


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## Treyconner05 (May 26, 2021)

NealXB2003 said:


> Both similar in design, construction, and materials? All else being equal, 1" of pitch is usually good for 200 rpms. But aluminum will spin up more than stainless because of flex, 4 blade will spin less than 3 because of the drag, e.t.c.


Both are 3 blade, one 9P is aluminum and 11P is SS. If I were to switch to a 4 blade for better hole shot, how would rpms change? How much better is SS for shallow water than aluminum?


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## NealXB2003 (Jun 8, 2020)

Adding a blade is about like going up an inch in pitch...... that extra blade will cost you about 200 rpms. That's why most say drop 1" of pitch when going from a 3 to a 4 blade. Keep in mind, these are just rules of thumb. Sometimes two of the exact same prop run vastly different due to manufacturing variance, or who in the shop finished it out after it was cast. 

SS is more durable. If you're running in mud, sand, or wood.....SS will hold up to abuse that an aluminum can't. If you're hitting rock bottom, neither is going to fare well.


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## Treyconner05 (May 26, 2021)

NealXB2003 said:


> Adding a blade is about like going up an inch in pitch...... that extra blade will cost you about 200 rpms. That's why most say drop 1" of pitch when going from a 3 to a 4 blade. Keep in mind, these are just rules of thumb. Sometimes two of the exact same prop run vastly different due to manufacturing variance, or who in the shop finished it out after it was cast.
> 
> SS is more durable. If you're running in mud, sand, or wood.....SS will hold up to abuse that an aluminum can't. If you're hitting rock bottom, neither is going to fare well.


Thanks!


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