I will be putting commercially produced rubber hatches in my Point Bennett. They will be recessed as well. As per this post:

http://justyakkin2.blogspot.com/2011/02/all-decked-out-3rd-step.html

I have the exact same hatches on my plastic boat. There they sealed with silicone (or equivalent) and bolted down as well. The problem is that my day hatch leaks a bit around the bolt holes - no matter how hard I try to seal them!! There are absolutely no issues with leakage between the rim and cover.

The new hatch kits are not drilled for bolts - although the spots are marked for them. I'm thinking on just using an adhesive to attach the rims.

My question is whether to use silicone (or equivalent) or epoxy. My concern with the epoxy it that it's so darn permanent. If you look at the sketch in the link above you will see that I can pop the rim into the recess and fill the space with either silicone or epoxy for a very neat and well sealed fit!! A black silicone would match the rims and be almost invisible in the recess.

Any suggestions / comments?