[oldbluesplayer]

dcobbett - re: "I was under the impression that the core really only acted as a filler"

I've heard that said before, but I will stand by what I said, that the outer skin/core/inner skin is a combination package, as far as strength, bounded on the perimeter by both the outer skin and inner skin attachment to the hull, reinforced in the middle by knees (if any).

Think about this - if the core was only a filler, and balsa core has a large history of use in boat building, why don't you see balsa cored transoms? plenty of use in hulls and decks, but not transoms - because it does contribute to the strength and stiffness of the structure - balsa cored structures allow some flex - which is desired in a hull, to provide some give, but not desired in a transom.

The innerskin/core/outerskin transom is essentially a long, thin (narrow), fairly deep, box. Even if that box were made of flat pieces of premanufactured G-10 Fiberglass 1/4" sheet, in that size, it will flex - only the core material stiffness prevents that, and the (motor) force input to the entire structure is passed to the rest of the hull thru the attachment of the inner skin and outer skin to the hull.

Just tryin to lay out the structural dynamics - I do hope you reconstruct the cut-out portions of the inner skin and bond that to the hull/sides.

just some thoughts for you.

Bill