There is no free lunch. Welding in new metal is faster, better and cheaper.
Problem sounds like electrolosis. Salt isn't the problem. Disimilar metals
is.
Steve

wrote in message
oups.com...
My friends 43'aluminum houseboat has developed some severe pitting on
the bottom. Since he bought it, it has been in a lift and will continue
to be - the pitting existed before he bought it. Some of the hull is
like new but bad pitting where there has been barnacles.

We are having it hauled and sandblasted Mon. The yard also has a
treatment which they guarentee will remove any trace of salt in the
aluminum pores. I expect we will find too much pitted area to
economically weld.

Question - how well will expoxy impregnated fiberglass mat adhere to a
well prepaired rough surface ?? Patches would be 1 to 2 ft. sq. Boat
does 8 mph max and we would be happy with a 10 year life to the
repairs. The longest the hull will be in (salt) water will be 1 week
and then back in the lift. BTW we will be painting with 3 coats of
epoxy paint after repairs.