puzzling prop electrolysis or corrosion...
 

Here is problem that has me puzzled, and looking for any ideas.

Today we hauled our boat, and I noted the prop appears to have some
electrolysis or other corrosion stress to it. The prop is 2 years
old, Bronze on a SS shaft. When hauled, its color is ink black and it
has these small 'corrosion worms' all over it. Each 'worm' appears to
be corrosion, is about 5/8" long and about 1/32" wide. There is one
about every 2-3 square inches.

I do not know the cause of this, and will have to investigate if it is
something on my boat leaking, or something from a neighboring boat.

Now, here is what puzzles me. The shaft zinc does not show any signs
of undue wear. I would think that if I had some electrolysis issue,
the shaft zink would be one of the 1st things to go...

Any ideas?

(BTW, the boat has unbounded underwater fittings, and all other Bronze
parts look normal)

Thank you in advance
-al-

puzzling prop electrolysis or corrosion...
 

Al

l sounds like you've got a problem with AC current leakage. It could
be comming from your boat, or a boat near yours. Have you got an
isolator installed on the boat? Their are ways to confirm if this is
the problem, but I don't remenber how it's done.

John