aluminum vs steel prop

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Pros of SS: you can run less pitch because of no blade flex, much more durable
Pros of AL: cheap, possibly some degree of l/u protection from prop strikes (debatable)
 
Quackrstackr said:
Pros of SS: you can run less pitch because of no blade flex, much more durable
Pros of AL: cheap, possibly some degree of l/u protection from prop strikes (debatable)

That is it in a nutshell



You will get more out of a SS prop - what are you putting it on?
 
If your gonna be around rocks and stumps, go with alluminum. If not you stand a good chance of snapping a shaft.
 
Aluminum props are not a cure all for l/u failures because of prop strikes. I've run both. Either of them can cause l/u damage. People have a preconceived notion that a ss prop is going to detonate your lower unit every time that you hit something but an aluminum will shed blades before it happens... it simply is not true.

An outboard isn't a mud motor that is designed for that kind of abuse, regardless of prop material.
 
That horse power on that boat I wouldn't go over 9 pitch.You don't want to over prop your motor.That is the quickest way to ruin it.You want it to run the max rpm's that it was designed for.
 
Your little 7.5hp motor is not going to be any faster with a SS prop. 200 hp motors only see a few mph gain.
Your boat is 16' right? 7.5hp is not much motor for that boat.
I like to think that aluminum props offer more LU protection then SS but its just a guess. I have gone through my share of aluminum props because of rocks in shallow rivers and never had any LU issues.

Another thing....I can almost guarantee your boat won't be any faster with a brand new prop of any material versus the beat up prop that you have. I have ran some gawd awful beat up props on my 25 hp and my boat speed never seemed to increase after a brand new prop install.
 
that is the exact opposite of what the dealers tell me... and then again they are looking for a quick sale, but they have said it will make a big difference in speed. i watched a video of a 7.5 merc on youtube plane a 16' v-bottom. i hope it makes a difference because it is so slow it seems more of a pain in the rear than it's worth somethimes, and reverse is even worse. i think going from 2 blade to a 3 blade will make some difference though, guess we'll see. probably go with the aluminum though because of the cost difference and if i decide to put it on the river it would be somewhat safer for the motor
 
2 blade props are more efficient than 3 blade. That's why you see a lot of those on small hp motors. 3 blades get better bite.
 
Mean16...... I'm going to be doing the same thing. My 9.8hp has a two blade prop, and I want to switch to a 3 blade prop. One of our neighboors switched his 2 blade to a SS 3 blade and can now plane a 16' Lund, with the same motor as me. Problem I'm having is finding someone who still makes em'. :x As far as efficiency..... I could care less.
 
what do you mean as far as efficiency? i just want to get to the honey holes faster than i am now with out harming the motor. i have been around bass boats all of my life thanks to my grandfather, but this is my first jon boat and i am learning something new everyday.
 
mean16 said:
what do you mean as far as efficiency? i just want to get to the honey holes faster than i am now with out harming the motor. i have been around bass boats all of my life thanks to my grandfather, but this is my first jon boat and i am learning something new everyday.

I mean as far as gas mileage. Its not too often I buy a toy, just to worry about its fuel consumption.
 
All things being equal, a 2 blade should be faster and more efficient than a 3 blade because of reduced drag and friction, less rotating mass, etc.

It just depends on what you want. More blades equals more low end performance and less blades equals better top end.

Notice on most trolling motor props that their 2 blade versions are usually marketed as "power props" while their 3 or even 4 blades are general purpose or weed whacker props.
 
Quackrstackr said:
All things being equal, a 2 blade should be faster and more efficient than a 3 blade because of reduced drag and friction, less rotating mass, etc.

It just depends on what you want. More blades equals more low end performance and less blades equals better top end.

Notice on most trolling motor props that their 2 blade versions are usually marketed as "power props" while their 3 or even 4 blades are general purpose or weed whacker props.

yes... all things being equal. Although when we are talking about a 7.5hp that will not get onto plane with a 2 blade prop, if the 3 blade prop gets it on plane, then it is definatley going to go faster, and also be more efficient, not just plowing wide open. Although I don't think a 7.5hp anything is going to get a 16' on plane. So???
 
Hey, I'm just telling you guys the physics of prop design and how it pertains to properly sized motors.

I can't help it that you both need motors that are actually suited to the task instead of trying to make them something that they are not. You can't make a silk purse out of a sow's ear. :lol:
 
mean16 said:
7.5 mercury on a 1636 monark
it is really slow right now with the 2 blade that is ate up from shallow rivers

what would be the best pitch?


I woudl not waste the money on a SS prop for a motor of that size. Instead, get a few different aluminum or even composite props with different pitch and blades and see which gets you what you want with your motor, hull and weight
 
What ever prop you get I suggest getting some type of prop protector. I have a Mac's River Runner on my motor.
 
Captain Ahab said:
mean16 said:
7.5 mercury on a 1636 monark
it is really slow right now with the 2 blade that is ate up from shallow rivers

what would be the best pitch?


I woudl not waste the money on a SS prop for a motor of that size. Instead, get a few different aluminum or even composite props with different pitch and blades and see which gets you what you want with your motor, hull and weight

Wise man.

If repeated prop strikes on rocks are a concern, I wouldn't get a ss prop regardless of motor size just from the refurb/replacement aspect of it. There's nothing cheap about ss props no matter how you slice it.

In that same thought process... beware of the composite props and rocks. Those are pretty much toast after one strike unless you can find one of the ones with replaceable blades to fit your motor.
 
I was looking for a SS prop the other day, just out of curiosity, and I'm not even sure they make one for mine? Do yall eer see SS props for the old style hub, 9" OMCs? I think my motor was on a sailboat before me, so certainly repropping it is worth considering.
 

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