Repairing Blind Side Stripped Holes on My Navigator

I don't know your boat but I was a shipwright, had a marine repair & salvage company and have done new construction and repair on everything but ferro cement. Screws going into wood or core eventually always leak or loose their bite. Epoxy holds much better than screw threads in almost anything. I use West epoxy with 404 high density filler added. The filler has additional adhesive properties. If needed you can make the epoxy/filler mix very thick, like putty.
Now days, when setting new screws in wood, cored fiberglass or fiberglass panels, I either inject epoxy into the pilot hole or mix a very thick mixture to a putty. Usually on a panel with no backing, I 45° the hole, paint with epoxy only and then press the putty mix into the hole and flush with the panel. After drying I redrill a pilot hole and also put epoxy on the screw or in the hole when driving the screw. In wood or cored fiberglass I drill an oversize hole and fill with a light epoxy/filler mix. After dry I drill a pilot hole, inject some epoxy and drive the screw. The epoxy lubes the screw and it can never leak because the screw is sitting in epoxy and even if the water seeped down the threads, it would be in epoxy not the wood or your core.