Whoa, what a detailed answer, this helps a lot! The main reason for trying to get away with replacing the transom is that I have no idea how to do this
For now I will not install an internal combustion engine because on the nearby lakes where I plan on taking the boat only electric engines are allowed. It will be a struggle, but I have to start somewhere. Of course, I'd love to have a decent engine someday, so if I invest the time in replacing the darn transom, I'd do it properly
Then there is a problem with finding the right plywood. I live in a place that's far away from the sea, so I doubt i'll find any "marine" rated plywood. I can get beech plywood that's rated for outdoor use in several thicknesses, for example a 15mm piece of plywood has 7 layers, 18mm has 9 layers. Would that work? If not, what exactly makes plywood "marine", maybe I can find something similar. What should I use for bonding the pieces together and for "painting" on the finished piece? Epoxy? Something else?
And then there is the question of how to unglue the hypalon and then glueing it back on the new transom and what kind of products to use for this.