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Discussion Starter · #1 ·
I have a 1992 Scout 141 Sport with a 1992 30 HP Yamaha 2 stroke. The prop on it came with the boat and is a very old and banged up 3 blade . I have no idea what the pitch is on it. I know it isn't much information but would a new prop speed me up any and any idea on by how much? Trying to decide if it's worth the cost.
Any recommendations would be appreciated
 

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Carpe Diem
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GIGO, a computer term meaning "garbage in garbage out". The quality of output is determined by the quality of input. You don't know rpm, pitch and can't really quantify how good or bad the current prop is. You've given us garbage for data and any opinions we can give you will also be garbage. Get more info and come back when you do.
 

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Discussion Starter · #7 ·
Well I ended up getting the motor going again and running very well now actually. I am learning as I go. So I hooked up the tiny tach and it read 6,050 at full throttle. And that was with a full load in the water. I don't know if I should open it up to full throttle when just hooked up to muffs. Not sure if it is harmful to the engine? The listed full throttle operating range in the motor's manual says it should run between 4,500 and 5,500. Does this mean I'm losing potential thrust and a new prop with a higher pitch could push more water while still maintaining 5,500 and give me more speed? I still don't know the pitch on my prop because it is unreadable because of how old and dinged up the prop is.
 
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Pick a prop, buy a prop, run with new prop. Give us the results. Now we can help you pick the right prop from there. Consider your new prop a spare for when you ding your other new prop we help you decide on;)
 

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Fly-By-Night
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3,190 Posts
Can't speak for everywhere but a lot of prop dealers will let you run a prop and bring it back in and swap it out until you find what works for you.

The only caveat being you cannot mess up the prop, like not even a scratch, wrench mark, etc... so find a deep lake or river and experiment.

With that boat and motor I'm going to say to start with a 10"prop with about 12p to start and check your RPMs, if you can hit 6k good, if you can't drop 1p and keep testing.
 

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Brandon, FL
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12,325 Posts
Well I ended up getting the motor going again and running very well now actually. I am learning as I go. So I hooked up the tiny tach and it read 6,050 at full throttle. And that was with a full load in the water. I don't know if I should open it up to full throttle when just hooked up to muffs. Not sure if it is harmful to the engine? The listed full throttle operating range in the motor's manual says it should run between 4,500 and 5,500. Does this mean I'm losing potential thrust and a new prop with a higher pitch could push more water while still maintaining 5,500 and give me more speed? I still don't know the pitch on my prop because it is unreadable because of how old and dinged up the prop is.
6,050 - was that in neutral or in gear driving?

"And that was with a full load in the water" - this is why I am asking.

The only time I would do WOT on muffs is if it was your motor, not mine. :) :)

You want a prop that when in gear is going around 5,500 rpm's. Higher rpms means the pitch is too small and less means pitch is too great. Also could be blade size and/or both.
 

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Discussion Starter · #13 ·
Did some more looking at the prop I do have. I scratched some paint off and found the number underneath it. I guess it had been repainted at some point. It is a 9 7/8 inch with a 14 pitch.
 
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Send it to a prop shop and let them tune it up. Run it and see how ya like it then. It will be cheaper than a new prop even if it’s aluminum.
 
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