: So.... what dimensions did you use? 2 mm buffer for thickness?

I reinvented the wheel, trying to make a double gasket system. There is a gasket on a lip underneath my hatch. I planned for a gasket on the edge of the hatch as well, so when I cut it out I cut very very carefully and precisely with a 1/8" carbide spiral router bit to fit 1/8 unfaced neoprene I was using for a gasket. It fits great- for about a week and a half, maybe two. Then it starts to shrink. It looks unsightly, and water gets in my hatch. I cut a taper that is just under 1/8 at the bottom, and just over 1/8 at the top. The bottom tends to get caught and bunch up, making the problem worse. Time will tell if it works- I'm giving it a couple of days for the adhesive to reach its full bond before testing/tweaking the fit.

In the future I will not be so precious. Any future boat's getting deck plates or VCP hatches.

m