I am changing my sea strainers on my boat to Perko style. My old ones from Wellcraft were crappy plastic bottoms and someone lost the strainers. I bought a pair of used perko strainers and they are the kind that have cork gaskets. the gasket kit is $40 for both. Instead of using cork gaskets that will just disintegrate, Im going to cut some out of a sheet of rubber gasket material. My question is what kind of rubber would be best? How thick?

I think this would work for your looking for.

http://www.keperf.com/p-16786-bulk-r...-material.aspx