I need to reseal my portholes on my 1984 Catalina 30. The aluminum on the cabin side of a couple of the portholes also appears to be blistered as well and that seems to be where the leaks are coming from. Do I need to replace the interior part of the porthole with a new frame or is there some kind of epoxy or bonding agent that I can use to repair the aluminum. What kind of material should I use for a gasket? Is there a gasket that is made specifically for this porthole based on year and boat manufacturer? For instance through Catalina Direct or do I hand cut it to fit? Is there a sealant that is used instead? Thanks for any help or directions to various links that might be able to instruct me.