I had planned to use 2 layers of 3/4" MDO sealed with epoxy. Finally started the project yesterday. Drilled several buck rivets on both sides of the transom...apparently not enough to gain access yet to the rotten wood.
Going to hold off from further drilling until I'm certain how many more (and which ones) need to be removed to accomplish this task.
Have been hunting all over the Internet to find additional info...no luck yet.
BTW...I found out exactly what I must do to gain access to replace. I'm going to have to drill about 100 or so buck rivets from the stern to the rear windshield support frame. Most of the rivets are along the gunwales.
Can you remove the splashwell without removing the gunnels? I rebuilt a transom using two pieces of marine ply encased in glass. I cut off the kick up on one side and could just get it into place.I put the cut off against the aluminum and slid in the next piece the opposite way with plenty of resin in between. I used a bunch of short screws to keep the boards clamped together while the resin set. I sealed the screw holes with resin when I pulled them. If I remember right I used 5200 to glue the first board to the aluminum, so it is not going to be fun to replace it. It held up for 18 years. One thing, don't put the wood all the way down into the bottom of it's slot in the transom and drill a couple of weep holes to let moisture drain from under the wood.
Unfortunately no. Not without tearing up the part of the splash guards...and possibly compromising the integrity of the structure. I'm okay with the removal of the gunwales. My transom is 1 piece and considering the maximum recommended outboard is a 90 HP...I would feel much more comfortable with a one piece. Besides...there is simply no way to peel back anything to gain access without drilling about 100 buck rivets.