Prop swap

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Hook1

Well-known member
Joined
May 26, 2009
Messages
5,041
Location
Rossville, GA
I have a 90HP Mercury 2 Stroke on my boat. Its a real lead sled. I am running a 3 blade aluminum prop and its a 13 x 21 pitch. I still get a good hole shot and all and at 4600 rpms on plane and trimmed out it will run 38 to 40 mph on GPS. The thing is if I go WOT trimmed out at 5200 rpms I'm only improved to 41 mph on GPS. My question is would a stainless prop help on the rest of the top end and not just waste the extra rpms and gas? I think I'm done hitting trouble areas and going through the aluminum props. If this will help get a little more from my motor than I will be in the market for maybe a used stainless prop. I cant afford a new one right now. Maybe someone knows where I can try one out before buying or something like that? Thanks in advance.
 
i went from 17 pitch aluminum to a 19 pitch stainless and now my 70 hp will run right at 40-41 mph.. and my prop isnt perfect.. i would think if you got a good stainless prop you would pick up some speed..Im like you it doesnt take much to mess up an aluminum prop that in it self makes the stainless worth it
 
My concern was tearing my foot up. When you bottom out an aluminum prop, the ears shear off very easily or bend. A stainless prop is gonna take out gears and all. I would like to try out a used one first. Thats a good bit of money to spend on a new one.
 
I'll second the Performance Prop. Just see Billy or Tim and talk to them about trying a few out. Their pretty good about that.
 
If you hit something hard enough, it doesn't matter if you have a aluminum or stainless prop, you are going to tear your L/U up. The reason stainless usually picks up speed is it that it doesn't flex and change pitch like a aluminum prop does. I have a few that will fit your engine that you are welcolme to try. I would have to look to see what I have. Just keep in mind right now your RPM's will be lower due to temp and humidity. So prop accordingly as the L-6 does not like to turn over 5800. Just my .02.

+1 on Billy and Tim!!!!!
 
I would like to try it out. It seems like my prop runs best at about 3/4 throttle. I think the rest is being wasted in flex and pitch reduction at full throttle. I started out with a 19 pitch on the motor and the hole shot was awesome but if I tried to trim out much at all it would cavitate and just blow aut of the water. I get much more trim with the 21 pitch but I think the stainless with little to no flex would improve my top end. My boat won't be fast no matter what I do but I hate running 3/4 throttle and just wasting gas after that.
 
They help porposing and hole shot. If the prop is blowing out and the rpms are go up it will not help. The prop is loosing it's bite. It is just a characteristic of that prop. Different props will react to different situations. That is why there are sooooooo many choices. Wish there was a do all prop. If it was a problem with the boat or set up, your other prop would do it as well. Just my .02
 
Fshn Cpa - 7/21/2010 5:22 PM try Performance Propeller in Soddy Daisy. 842-7767 They have some rebuilt ones
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"Ditto" Tim knows his stuff about props. He may have a used prop or two that will fit your need. In addition he can tune a prop to adjust the performance to your boat. Do not waste your money experimenting. Go see Tim.</p>

I posted a "How to tune your prop to your boat" thread a while back that would be very helpful to you about now. I will see if I can come up with it.</p>
 
Hook1 - 7/22/2010 2:34 PM I would like to try it out. It seems like my prop runs best at about 3/4 throttle. I think the rest is being wasted in flex and pitch reduction at full throttle. I started out with a 19 pitch on the motor and the hole shot was awesome but if I tried to trim out much at all it would cavitate and just blow aut of the water. I get much more trim with the 21 pitch but I think the stainless with little to no flex would improve my top end. My boat won't be fast no matter what I do but I hate running 3/4 throttle and just wasting gas after that.
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Engine too deep on your boat! ???</p>
 
I run a 23P on my Tracker that you are welcome to try if you want but I don't know the dia.

Bill
 
No one said anything about buying a bunch of props. I have several he can try for free. The only money spent will be in gas. Props have different charaterics, prime example is he has 2 props and one blows out at very little trim (probably has very little cup) and the other does not. This is usually a indication of the engine is too high for this prop to keep a "bite" on the water and gets too much air around the blades. Some props are made for specific operations. Here is a video of Wes's boat running my 26 Chopper. Notice the water line. When he trims up the propshaft ( where the sharp point of the case is) is running level with the surface and 1/2 of the prop is out of the water. This is why you need a low water pick up to run these props to get the most out of them. If this was a tempest, trophy, aluminum prop,ect. they could not hold their "bite" and would blow out. Notice toward the end of the video how aerated the water gets and this make it that much harder for the prop to maintan a bit. Just my .02

I gave Performance a +1 in my first response.

Video of the bullet running.
http://www.youtube.com/watch?v=QJ0ZRt_isN4&feature=channel
 
wrechin2 - 7/25/2010 4:31 PM

No one said anything about buying a bunch of props. I have several he can try for free. The only money spent will be in gas.

Same here James, he can try my 23P for free if you don't have the same type for him to try. My prop is on the motor and the only one I have, it ain't for sale.

Bill

BTW: Per our conversation yesterday I drained all 3 carbs and no excess oil in the gas so I'll try the small reserve tank next but I have the feeling a trip to Dunlap is in order
 
I will more than likely be going to Marion County park this weekend if I can finish up another engine. If you can make it there, I will dig these props out and bring them for you to test. emoToast
 
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