I had a slight twis in the back. It was 1/8-1/4" out of square with the back deck at the transom. I built an elaborate strap system that allowed me the pull one side forward with my Prussik rope. Bolted to the wall in the back, so I could run a Prussik rope to pull that corner back. In ran a 20' nrs strap thru that bow loop pulling off anchor points in the floor to keep the boat where it was. I ran a side pull strap to the corner that had to go forward. Sideways pull helped align the transom with the panel along the side panel joint. Lastly, I bolted a few pieces off wood to the ceiling joists to allow me to use spreader claps to push the transom corner down. Worked good. I got it pretty darn close.
Weather in the high 20s allowed me to heat the shop and get this final layup done on the hull. The transom was originally made with joined 5/8 corecell. With only glass on one side it still seemed flexy. I don't know if ill ever hang a motor off the back but I decided to just build it so I could down the line. Cored the bottom transom with a smaller 3/4" coosa board piece. This creats a ledge that the back deck sits on for support. The top got a full width piece of coosa. I noticed all the commercial drift boat companies really beef up the transom tops to allow a good mounting point for a motor. I thought about hollowing sections to core with plascore for weight savings, but decided the small pieces wouldent save much in weight but would take a lot of time.
Layup on the bottom of transom is s glass scraps between coosa and foam. Over top it's 12oz biax tape at side panel transom joint/s glass/12oz biax/10oz
On the top of transom is 6 oz between coosa and foam. Over top it's 12oz biax tape at side panel transom joint/10oz/12oz biax/6oz. The transom may get some 1/2 hardwood plates too. Haven't decided. There definatly will be a nice grab handle at the top of the transom. And a nice arc cut in the top.
Boat strapped in to square for last hull layup
Back deck dry fit on lower coosa board support acting as a cleat