I managed to get the remaining vinyl off the boat today using a heat gun and several stripping knives as I kept breaking them. Don't know my own strength sometimes!
Once it was stripped I could see the extent of the damage and like most things on the boat far worse than I expected, 40 years have not been kind to the old girl. I cut the worse part of the rot out, using a circular saw along the joists of the roof, using the screws as my alignment. I then used the saw to cut out the inner parts of the root then using a chisel removed the remainder on the joists, you can see the extent of the hole below:
You can see from the photo below than the ply making up the roof had rotted through a couple of layers and in some cases just de-laminated:
My plan was to mix up a batch of epoxy filler, wet out the roof, pour the filler over and then over plate the whole roof with 12mm ply, creating a sandwich. The resulting structure should be solid as a rock and last another 40 years. This seemed to work and I'm more than pleased with the result, I need to fill the edges and sand the edges to create the curve of the roof on the new ply.
While going over her I also found that the deck by the bathroom and also the panel that made the side of the bathroom, plus the timber running up the hull was rotten. After several hours with a hammer an chisel I'd got the worst of it out. I'd spent sometime in the past removing the front deck and it took an age, I realised that there must be an easier way, then it hit me, pull all the nails and screws out and use a power plane to remove the timber, then sand it.
Then it was a simple case of cutting a new piece to length and then use a router to trim the edges, the result is a perfect fit, glue it and screw it in place:
As you can see from the following photos, there the panel was quite large, nearly 4' wide, you can also see the rotton part of the rear panel on the port side:
