There’s a two part sealant (yellow and black that make green when mixed) we called splash zone that I heard was developed by the navy for patching boats. It sets up under water and you can use water to smooth the surface. Once it sets up, it’s rock-hard and holds well. We used it to cover bolts on the bottom of commercial fishing boats in BB so we could skip over nets. I bought some at the gear shed and use it for lots of boat type projects. It’s awesome stuff.
Resetting the rivets can be a bit of a job but by far the best rout to go. I 've done several small boats and I 've also seen some that had some kind of sealant used but small boats flex a lot and it didn't seem to hold up very long.
