I'm currently redoing all of the gaskets on my old Bomar
cast bronze port lights.
The gaskets I'm using (part # P100-52) come with a strip of double-sided tape already stuck to them. The idea is that all you have to do is tape them onto the port light, but it did not inspire confidence as a good enough means for creating a water
tight bond between the gasket and the bronze. The originals were glued, and I take a good deal of green water
over the course of a season - not to mention the 30 seasons that the old gaskets lasted.
I called Hamilton Marine
and spoke with a very knowledgeable guy named Kent who advised that I use Sikaflex 221 to glue them in. Of course proper preparation of the surface is just as important as using the right glue. Kent's best advice was that I make a seemingly over-sized scarf joint (at least two inches) to join the ends together.