Aluminum to stainless prop size

[tprice]

I have done the 20 hours on my new motor and have had it serviced.

So far I am pleased with performance but it came with a standard aluminum prop and I always like the stainless better and feel it gives better hole shots.

Now I do not have a local "prop shop" as some call it to go out and test various props but if I replace my aluminum prop with a stainless of the same size
what should I expect or is there a rule of thumb to convert aluminum to stainless

[skyranchrob]

I just replaced my alum. with stainless and found the Michigan Wheel (props) site helpfull. My problem was I was reving over 6000 so I went two sizes up in pitch, from 19 to 21. This lowered my rpm down to 5700. There site says a two point increase is good for a 400 reduction so my guess is the stainless helped by about 300. Rob

[ken2]

depends on what brand stainless your going too, and what brand aluminum you have.
With Mercury, I normally expect a 100-200 rpm decrease if going from aluminum to the exact same size SS.

Yamaha may be different, if your going with a yamaha prop. I'd ask SIM

Here is a site that did a bunch of test on SS vs AL and Composite props for the same boat.
You can look through and see the differences between them all depending on brand.
It varies a lot.
Its about halfway down the page.
http://www.acepropeller.com/prop-test.asp