I have removed 10 bronze ports on my boat in order to repaint the deck.
There are 2 different styles of port - opening and fixed - each set with
approx. 75 stainless steel round head mounting bolts with washers (on the
exterior). Under every one of the washers on one set of ports is a small
rough irregular crater about the size of a wooden match head. Under the
washers holding the other ports, the metal appears unblemished. Are the
stainless bolts a likely culprit for the pits and different bronze alloys
the explanation as to why the pits are on one set of ports and not the other?

Yes. Get bronze fastenings.
"John Knox" wrote in message
...

I have removed 10 bronze ports on my boat in order to repaint the deck.
There are 2 different styles of port - opening and fixed - each set with
approx. 75 stainless steel round head mounting bolts with washers (on the
exterior). Under every one of the washers on one set of ports is a small
rough irregular crater about the size of a wooden match head. Under the
washers holding the other ports, the metal appears unblemished. Are the
stainless bolts a likely culprit for the pits and different bronze alloys
the explanation as to why the pits are on one set of ports and not the
other?

Yep. Make sure you get silicone bronze fasteners, NOT brass. A good
source is http://www.jamestowndistributors.com. No commercial
connection, just a happy customer.

Jim Conlin wrote:
Yes. Get bronze fastenings.