Jim wrote:
It appears that you are quite knowledgeable on the subject.

Oh please.

I'm just an old outboard mechanic(both me & the outboards).


What are your
thoughts on the relative merits of aluminum vs. stainless steel recreational
boat propellers?

For recreational boats, under 50mph, aluminum is just fine.

I have one AL 19p for one of my 115 Evinrudes that performs just about
as well as as my SSTII 19p prop. I had it double-cupped at rebuild
years ago and am very satisfied. It just blows out a little faster in
hard turns with lots of trim.

At higher speeds, blade shape, contour, & thinness is much more
critical, and SS provides the builder with the ability to make a thinner
blade. The blades can do their work w/o displacing as much water as
with AL.

AL is ~1/3 the cost of SS and is more forgiving to your gear train in
the case of striking a submerged object. You are more likely to lose a
blade or two instead of banging up a SS and putting a little "english"
in your propshaft.

SS is for optimal performance. Some special SS applications do exist,
like if you are running through sandbars often. The SS will get
polished, the AL will get "resized".

4 blade props are overkill unless you have a hull design that can
benefit from the extra surface area to correct a bow-heavy porpoising
situation. The most efficient props are 1-bladed, but they are tough to
balance. Three blades seems to be a good compromise for mid power & speeds.

In all reality, AL is the best choice for recreational boating. Always
carry a spare, & the tools to change it.

Rob



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