: I'm putting semi-soft pad eyes in my new boat. I using
: 3/4"webbing but I've made plywood backing plates (see
: image). I like the idea of the flat plate for making a good
: waterproof seal.

You have such a large piece of wood that you could probaby use any household caulking compound. There are a lot of inexpensive acrylic /latex /urethane based caulking compounds. Run a bead around the weebing and when you pull it up the caulk will squish a bit between the inside of the deck and the wood base of your padeye. Once it hardens it will be a fine sealant and a weak adhesive. With the decklines in place you don't need any adhesive at all to hold the padeyes in place, so the strength of the adhesive is irrelevant. Inexpensive caulk will keep out water just fine. When it comes time to replace the padeyes or the webbing, a sharp tap will dislodge the caulk, and it can be cleaned up by gentle sanding.

PGJ