Advice on strengthening hull

I would look into the Coosa if I were you. There is a reason that your transom is needing a recore. I have pulled lots of de-laminated/rotten ply out of boats. It's a good feeling to know that when the Coosa goes in it is the last time the repair will have to be done.

I would be interested to have the numbers for the Coosa board. It is VERY tough stuff but again, empirical findings are central to determining material selection in boat building/repair. Boat building has come a long way- what are the top end builders using these days??
I do most of my work in Annapolis and mostly on sail.

Regards