Do you feel the difference?

[Dam2009]

For those who interchange stainless steel prop with aluminum or other material on a 5L MPI Mercury, do you feel the difference in performance?

 

[Mischief Managed]

Re: Do you feel the difference?

Absolutely. The 5.0 has enough torque to really flex the aluminum prop blades and it feels mushy. The SS prop will have a more "connected" feel and should also allow quite a bit more trim without ventilating.

 

[steelespike]

Re: Do you feel the difference?

I've never made that change but I can say that a new very good al prop going to an new entry level ss prop the difference would be
relatively small. The Turning Point al props do well and the Solas Amita and Rubex al, for the dough do really well.
A ss prop will hold up better in contact with mud or sand but in a hard contact will cost about twice as much to repair. Also if the safety hub fails to release there could be gear case damage.
Also the change would depend on what you're trying to improve.
Someone should be along with more details.

 

[agallant80]

Re: Do you feel the difference?

I went from aluminum to SS but I changed drives and boats. Had a Alpha 1 Gen II and now have a B3. I can't say there is anyting I miss about an aluminum prop, SS puts up with a tonne of abuse it seamed like every time I hit a twig with my aluminum prop I had to replace it. If I ever go back to an Alpha one then SS it is for the prop. Just for that reason alone I would highly reccomend a SS prop to anyone.

 

[BobGinCO]

Re: Do you feel the difference?

Absolutely.

I am intrigued by that statement. Enough so, to wish to put a full accelerometer package onto a boat, and try to measure the difference. I would also love to see evidence that an AL prop flexes. Actual video, or something. I'm just such a skeptic, that I question all of this stuff that appears to be "tribal knowledge" and "faith-based statements". Mind you, I'm not saying that you don't believe what you're saying, I'm just saying that I would like to see hard evidence that it is real.

 

[Alwhite00]

Re: Do you feel the difference?

I went from a 3 blade aluminum (14.25 X 21) to a 4 blade stainless (14.125 x 19) and it was like I bought a new boat - Great holeshot and same top end. (GPS)

LK

 

[Frank Acampora]

Re: Do you feel the difference?

Well, I never did it with that package but have done it on outboards. I don't think there would be any real difference between outboard and inboard/outboard powered hulls.

With the outboards, there is a real difference of about 200 RPM and 1 or 2 MPH MORE with the SAME BRAND, SAME MODEL prop in stainless. Since different brands and models have different blade area, blade design, effective pitch, and rake, there is no comparison directly between--say--stock aluminum and aftermarket stainless props or various brands of props.. In fact, you can not even compare two different brands of stainless because different designs perform differently. That's why so many people have trouble finding the correct prop for their application.

As far as "flexing" I don't know. Typically, stainless blades are thinner than aluminum in cross section so there is less parasitic drag. That is, it takes less horsepower to actually spin the blade through the water so more HP is available to drive the boat.

You CAN find aftermarket aluminum props that approach the performance of stainless but usually there still is a slight difference.

 

[Mischief Managed]

Re: Do you feel the difference?

I am intrigued by that statement. Enough so, to wish to put a full accelerometer package onto a boat, and try to measure the difference. I would also love to see evidence that an AL prop flexes. Actual video, or something. I'm just such a skeptic, that I question all of this stuff that appears to be "tribal knowledge" and "faith-based statements". Mind you, I'm not saying that you don't believe what you're saying, I'm just saying that I would like to see hard evidence that it is real.

I have found that slip percentage increases more with AL than with SS as speeds increase. With no evidence of cavitation or ventilation, the only explanation I could come up with was flex.

 

[jestor68]

Re: Do you feel the difference?

I have found that slip percentage increases more with AL than with SS as speeds increase. With no evidence of cavitation or ventilation, the only explanation I could come up with was flex.

And more cup.

 

[jestor68]

Re: Do you feel the difference?

The prop makers engineering departments have video and photography of propeller behavior in their test tanks(sort of a water wind tunnel). Since the data is proprietary and protected, not certain they would release it to the general public unless it's old data not worth protecting.

Speaking to one of their engineers and having him/her explain how/why a propeller blade flexes might be helpful to your understanding of how these things work.

 

[tpenfield]

Re: Do you feel the difference?

Here is something that discusses propeller flex and relates it to a term called "yield".

Aluminum,composite and stainless propeller flex | Ace Propeller

So, perhaps there is a way to measure "propeller yield" :noidea:

 

[500dollar744ti]

Re: Do you feel the difference?

With an aluminum prop my boat looses top end and rides like crap. The SS prop gives me more top end and more lift for a more stable ride. I was trying out an aluminum prop to compare holeshot with a different pitch. I run a 20p solas titan SS prop, I swapped a 17p mercury aluminum prop with hopes of a better holeshot and worse top end. All I got was worse top end and terrible ride quality.

It's amazing that the SS prop can create so much lift that the ride quality is dramatically increased.