Joe
I think that if you stand back a little from this and read your own words,
you will clean it up and put it back. From where I sit you are saying that
original construction was 1/8 aluminum, and that you have a replacement made
from 1/4 SS. I've no idea of the loads or stresses, but if the original alu
was anywhere near good enough, then 1/8 SS would have been overkill. Or if
the original was under-sized, the 1/8 is OK. So even if you had lost 50%
thickness all over ( which you don't sem to be suggesting) seems to me you
are still well into the OK range. Just remember that SS requires oxygen for
it's corrosion resistance and don't go overboard on sealing/bedding which
might exclude oxygen and accelerate corrosion.

If you are accepting the advice of the rigger who replaces the 1/8 alu in
1/8" SS, why are you planning to go back with new 1/4?. What thickness are
the new Schock ones? What grade?

I suggest you could either stay with the 1/4 SS and inspect it again in a
few years, or make the replacement out of 1/8" and be pretty comfortable
either way .....

Regards
David

"joe anglim" wrote in message
om...
Thanks for the comments. I can respond to some of the points made:


It's true that there are lots of these boats around here, and lots of
collective wisdom. Opinion 2 came from a respected rigger with years
and years of Santana experience. He replaces the stock aluminum
chainplates with 1/8" stainless.
Schock also sells new chainplates now that they are selling new
santana 22's again, but the bolt pattern is different on the new hulls
so I would have to mess with the bulkhead. Same case for the standard
Schaefer plates.
I'll look more closely before buttoning everything back up, but the
plywood seems to be in pretty good shape - some varnish has
dissappeared, but no apparent softness in the plys or raised surface.
I do have slotted caps and will caulk well.
I'm not wild about going to mild steel/paint or spending much money or
effort improving the ones I have. If I'm going to mess with it, I
want less worries, not more.
The $200 quote was for 316 at a generic machine shop - I had to
describe what a chainplate is and does, I take that as a good sign but
I probably should have just said it was for farm equipment. I didn't
ask them about 316L.

My gut feeling is that if I don't replace them, I'll probably worry
about them enough that even if there is no spectacular failure on the
bay, the $200 would have been worth it.
I'll have to check with a friend to see if he can handle stainless in
his limited backyard shop.

McMaster-Carr's price for a 2" x 36" x 1/4 flat bar of 316 is $42
plus shipping. They don't have the 316L in 2" bars so I would have to
cut down a larger plate, for $65. Local would be a better bet anyway
to avoid shipping...

Thanks again. I appreciate all the fast responses.
Joe