Here the spashwell has been cut out along with a little bit of the floor.
When I started to dig around at the top of the transom from the inside the original wood had the feel of cardboard but only half the strength, this dried out mush proceeded to get wetter and mushier the lower down the hull I worked, only the very highest-up outsides of the transom was dry with the wood in as new condition. This good wood proved a lot of work to chisel out, I preferred the mush!