I got email from someone today who asked about a 1962 boat:
Good afternoon buddy I am ready to glass the bottom of my dory Should I glass over oak chines?
It was mostly gone when I got the boat
The return email address was garbled so I wasn't sure if my reply went through or not. So I'll put my answer here too:
Honestly I'm not sure about the answer.
I have built quite a few boats where epoxy/fiberglass goes over top plywood during construction, so both sides of each piece of plywood is covered in glass. https://localhost/mrb/fragments/Drift-boat-info/Vidalia/boat-strength.pdf .... shows glass covered plywood (both sides covered) is 2 to 3 times stronger. Glassing just one side however, doesn't add much strength.
The real problem of glass over plywood is moisture. It gets into the plywood eventually and then the glass de-laminates.
If you were going to glass at all cut off the chine bumper and glass the bottom and the chine and up the side 2 or 3 inches. But even then...the glass might just be a moisture trap.
So I'm not 100% sure what the best way is with old framed boats. Maybe it's to leave them the way they are. And if the bottom plywood panel is completely used up--after 50 years--then maybe it's best to just add a new panel.
And maybe it's best not to glue that bottom panel to the ribs (if you can get it off without destroying the ribs). There are Marine Grand Silcone Caulks you can buy that hold with great tenacity. You can screw a bottom on with a half a zillion brass-alloy Torx screws, over Marine Grade Silicone, and then get a good bottom. But that silicone is still not glue. If you put something together with Marine Silicone and screws (unlike glue) you can get it to come apart again too.
Do I know this will work? Has anybody ever built that way before? Not that I know of. I'm 1/2 way through a boat like that now. I'll likely be getting it wet this coming March.
We'll see. This means, at the end of this coming Winter, I'll either be smart or I'll be dumb. We'll see. I'm taking a big chance on a big boat. I have a hunch I won't be dumb. But..............it does remain to be seen.