Fiberglass backing plates work well with fiberglass.
3/16"or 1/4" solid work well depending on aplication.
I make 4x6 ft. sheets w gelcoat and cut with a jig saw.
nice finish/no paint
Stainless and aluminum will corrode.

"sel1" wrote in message
...
Hi all,

I want to put on backing plates for all the stuff attached to the transom
(exhaust ports, swim platform, steering arms etc). Through continually
snugging them, the previous owner has burried a couple of nuts through the
glass! I am really new to all this but the first thing that comes to mind
is
reaction between two metals. If I use stainless bolts, could I use
aluminum
for backing plates or maybe I should use something else, or maybe I
shouldn't do this at all?

Still asking and not able to answer much yet.

Thanks, Steve