Stainless or Alum?

[brodie123]

Hi All;

I'm pushing a 19" heavy boat with 185hp Merc I/o - getting dead on 4400 RPM (which is WOT spec by the book)

I have a 19" alum prop

Is there any 'real' advantage to going to stainless of the same prop spec?

Will I actually notice any difference?

thx!

 

[solar7647]

Re: Stainless or Alum?

The big diferance is under load am aluminum prop will deform as a SS one will not. This will give a SS prop better hole shot vs aLuminum.
This can also be a problem causer because if you hit something with the prop like a sunkin tree or rock chances are the aluminum will bend or break thus saving the drive shaft from damage. A SS prop on the other hand will most likly not bend or break and can lead to a bent drive shaft.

I would stay with an aluminum pro just drop the pitch, every inch less in pitch you go you will gain about 200 RPM.

 

[steelespike]

Re: Stainless or Alum?

Do you have your speed @ 4,400? Without the speed there is no way to know if your prop is getting you the best performance.How is your hole shot?Performance as you add weight?If 4,400 is your max rated rpm your right on but the Q is how fast?
Any prop change needs to be based on your performance specs and the details of your boat.What is a "heavy" boat? An arbertrary change to ss could result in a few tenths difference to several mph in the extremes. I would stay with aluminum if you can get the performance you want. There are plenty of al props that perform very well.

 

[brodie123]

Re: Stainless or Alum?

speed at 4400rpm is 77kmh
weight - hard to say, old fiberglass 19' boat

 

[brodie123]

Re: Stainless or Alum?

seems alum is a 'safer' bet for minimal performance gain

thx!

 

[northernmerc]

Re: Stainless or Alum?

For a smaller motor on a fishing boat, aluminum props are fine. But for a powerful motor on a larger boat, you may want to consider a stainless prop.

Aluminum props are much more susceptible to damage and more frequently need repair or replacement. Even a light touch on the bottom or on a submerged log can take a chunk out of an aluminum prop.

One also can buy various prop designs (such as a five blade prop) in stainless that may not be available in aluminum.