SS vs ALUMINUM prop

Nautical

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I was under the impression that above a certain HP you pretty much had to use a stainless prop. However, the boat I just bought, which has a 225 HP Honda, is equipped with an aluminum prop. When I told one of our mechanics I wanted to put an SS on it he strongly recommended against it. His reasoning was that I would only gain 1 or 2 mph but should I ever hit something, the aluminum prop would sacrifice itself whereas the stainless would allow a lot of expensive damage to the happen to the lower. He also said he finds SS props very rarely on pontoons (but he doesn't like outboards and tries to avoid them). For me this was the first outboard with a larger than 200hp engine that I've seen (and I've seen plenty) that did NOT have a stainless prop.

I can live without the extra 1 or 2 mph because the former owner told me he reached 51mph with clean toons (and he said this after the sale was complete so no motive to embellish).

What do you think? I see 3 options here:

1. Dump the aluminum now and go with the good stuff
2. Run it until such time as I have to change the prop for whatever reason then go with the good stuff
3. Not worry about it; "live and let aluminum" and enjoy the perpetual savings

What say Y'All?
 
Stainless is recommended for over 150 HP , aluminum will flex .Hubs are available to help prevent that damage

 
Your dealer is not wrong. But oh, I do love me a shiny prop. I also don't boat where hidden hazards are an issue. Save your pennies and keep what you've got.
 
I go with choice 2 with the caveat in my 2nd paragraph below:

I’d wager you gain more than 1-2 mph given the flex that aluminum props have on 150HP and above motors. I find that statement by the person at the dealership very off base from everything I’ve ever read, experienced, or heard from others with real world experience. On our lake, SS is certainly the norm at 150 and up, even most at 115’s (although I question the benefit in the 115HP and down motors myself).

Now all of that said, so long as my RPM’s were solid at WOT, and I was hitting 51MPH, I would just tick with the aluminum for now, and only spring for the SS when the time was needed. If your motor is running in an ideal RPM range at wot already, and preforming like that, why spend so much now? …unless you want a spare prop anyway! Then the aluminum could be that if you do the SS upgrade.

Transfer of force with a SS prop to yoru lower unit is a real concern. However, that can be avoided by a hub kit as Jack mentioned above.
 
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My mechanic ... not a dealer, just a stand alone, always busy, always angry, independent boat mechanic. I broker boats now and then and have two I call "my mechanic" as we use them a lot.
 
FWIW, I have seen firsthand one Mercury 150 that was very difficult to shift with Alum prop.
Dealer put on a SS prop and instantly shifted smoothly.
The extra rotating weight is definitely beneficial.

Now this particular engine may simply not be as well balanced as most, because I'e seen dozens of merc 150 with alum & no issues.

Performance gain with SS?.... meh. Most noticing it is probably placebo effect.
 
I think your mechanic is in the minority, look around the marina and most high HP motors have SS props on them for a reason.

As to the "safety" of an aluminum prop, to me that's more 6 on one hand half a dozen type of situation. My SS prop will go through chunk rock, old stumps, shell beds etc. and barely nick - all while maintaining balance. Once a year I'll take a file to it and work out any burrs. The skeg will do most of the work to protect the LU from the most damaging strikes and as others have said the hub will spin in a catastrophic situation.

With an aluminum every little bottom contact or floating debris will dent, chip and deform that prop, not only diminishing performance but also creating an out-of-balance prop. That could then generate heat and vibration which may create another form of risk to you LU gears, bearings and shaft seals. Having to constantly repair and balance an AL prop to me - plus the lower performance - may cost more in money and hassle factor over the life of the boat.

Finally, add in that a SS prop will be less likely to break an ear and strand you out on the water and it's a clear no-brainer to me.
 
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