So I picked up a project at the start of COVID season. Good bones, but needed the wood replaced, so I've been cutting up some spare plywood to get some forms for actual flooring. I'm at the point where I need to do the transom and I don't see a great way to get to the "horns" at the top of the transom.
Click the photos for big versions.
Basic view of the transom space
The "horns" that go up under the cap, hard to see, but they go up about 1.5-2 inches under the cap
What I thought about doing is peeling the rubber trim line around and drilling out the rivets holding the cap on. That sounds like a bit of a pain, though.
try starting with a roll of cheap brown craft paper or gift wrap. start tacking it in place across the bottom with small pieces of tape and push the rest up into the seam where the transom joins the hull. then run a pencil around the perimeter. that may be enough or you can transfer that to something more substantial. I like insulation foam as its easy to use for other things like tracing the pattern to your 1708 or chop mat. see pic below and watch video if you like. this one had some big horns as well! hope that helps-
around the 3 min mark the transom pattern starts
more recently, I did something similar on this one working the top of the boat on. had to do one solid piece and one 2 piece to get it up behind the engine well. then glassed the seam
on video between the 2 and 3 minute marks