I made the tee piece by using 3" deck screws 6" apart, screwing the two 2 x 6's into a tee. It was soo stiff it pulled the transom flat. My boat is a 71 and the transom and artful aluminum work had deformed the transom to less than flat. The original transom under the rotten plywood was only gelcoat and 2 layers of mat 3/4oz mat as best I could determine. I put a layer of biaxial on the transom and let it harden before I glued on the Coosa. I also borrowed 8 deep c clamps from a neighbor to clamp the coosa to the hull. You don't want air gaps there. You will loose a lot of strength if the board is not glued to the hull. I made a thickened paste of SLOW set epoxy notch troweled on the transom and Coosa. Put the board in and bolt and clamp as many places as you can. I used 4" square backer washers on the outside of the hull to keep from having the bolts pull a dimple. Borrow as many deep c clamps as you can from a cabinet maker. They will reduce the number of holes you have to drill in the transom. Drilling holes to clamp the transom bugged me but I was determined to get the Coosa tight to th transom. I then put three layers of biaxial over the Coosa. I then put in three knee's from the hull to the transom. They are on a 45 from just under the motor well to the hull. Did I mention I removed the livewell? The original live well was used to stiffen the transom. Without the livewell you need stiffeners in my opinion. Be sure to get a 1/2" radius router bit to round off the corners of the Coosa. It makes the biaxial lay nice. The attached shows the inside during construction.
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