Man, that is a lot of work.
Are you going to soak the plywood in resin to help protect it? How are you going to join the pieces of plywood?
sorry man...didnt mean to ignore you...
yes. plywood got a layer of resin prior to installation. two in fact. first one, had some areas that soaked in more than others....i gave it a bit of a sand and another coat. as far as the two pieces of wood...well....of the original transom wood, only about a quarter was good. still very adhered to glass and very solid.
any and all of the rotted or rotting wood, was removed. this exposed the transom fiberglass, which was sanded. the new plywood went on in three parts. at the seam of each was a bevel cut so they overlapped...maybe not needed....but there. to install i mixed up some peanut butter...resin, cabosil and chopped fibers to a thick, peanut buttery consistency...and used it as a glue, i spread it on transom and new wood, extra thick on seams. installed new wood. then clamped new wood to transom. all peanut butter that squeezed out was spread over seam....or shaped to create a fillet. after all cured...i gave it a quick sand, to remove any stray strands from peanut butter, leaving a smooth finish...then a layer of mat and cloth over the whole transom, tabbing into the hull.
thats where i stopped.
hope that answers your question...sorry for he delay...