I think conger is right..the cap looks to be cored. Looks like foam sheet core though. Ya got a ply deck though so check that out real good.
Back to the transom..I really think you would be making a big mistake doing this from the inside. IMO I think the factory did it from the outside.
If you think about it there is no way to completely build that transom into the mold. Its not like other boats where they can install the whole thing and then cap it. The cap is Half of the transom mating area. So the upper half of that thing was glassed from the inside only ( at least it look like a finish rail was there ). They certainly didnt glass wrap the deck where it says 'Magnum'. The transom might have been installed after the hull/deck was joined up..Glassed like hell on the inside and then glassed on the outside. Or even preglassed on the outside and then finished.
Im just sayin..you cut out the inside glass lams..then your left with a big hole. Now you have to glass inside and out instead of just out.
Is that a perfectly flat transom? If so you could get some formica..spray it with gelcoat..add a few 3 layers of mat..set your pre-made trans core on it..then pop it off. Glass/glue/smoogie that sucker in there and finish out the sides.
If you need to you can add extra build on the inside. In fact I would go around the hull/deck joint and look for places you need to glass tab. looks like someone tried to 'fix' a few places from the outside..but you do it from the inside ( all the way around if needed ).
Its been said that IF the bottom hull is a core sammy ( foam or balsa ) and wet..well then your kinda boned. If its solid glass your golden
Can you throw us some better pics of the transom/deck/hull joint please. Right there where the wood meets the sides/bottom ( especially the bottom half ).
