Nice to see the photo of Calista!
Adding the new section of keelson. Luckily the planking was in reasonable condition, and after removing the old skeg (yes the bolts were rusted through and it almost fell off), I cut out the damage to the transom. I then cut out the damaged keelson – big hole in the back – quite daunting! I removed the keelson with hand tools mainly, that which was in poor condition was easily broken up and then the decent bit had to be cut with chissel and hammer. I had to make the scarf by eye with a pattern, hammer and chissel. It was probably not perfect, but close enough to the new section which was much easier to shape on the bench (I could get power tools to it). I have not used bolts on the new skeg by the way, it is held on entirely by epoxy. There is a section of the skeg which fits onto the back of the transom, which helps support it from sideways movement.
I have lots of photos somewhere – but cant find them quickly. Will see what I can find.