I have a question for those with more glassing knowledge than me. My transom skin has this break in it. Am I correct in assuming that I want to repair the crack on the inside before I attach the transom? Or will the PB and plywood be sufficient? I would appreciate input from the more experienced!
First let me say, excellent prep work!
Second, I would slap a double patch on the gaping gash sooo fast! 1708 with a 6" overlap all the way around for the first layup, and then 6" more all the way around for the second layup.
You may also want to consider "fairing the patch out" on the inside to keep it from telegraphing to the outside when you install your transom core. After the core is installed I'd do at least one layup of 1708 on the outside at the gaping gash, but 2 would be better... in the same manner as the inside repair, 6" and then 6 more inches. Fair accordingly, use a big knife! 12" sheetrock knives are underrated.
This is just the way I would fix it, some other people may just want to rub some boiled linseed oil on it and let it go, I think it needs more than that.
I really enjoyed your demolition portion of this build, it's just amazing how rotten the f'glass boats can get... and the Carpenter Ant colony was an added bonus!!!... the only thing better would've been better would've been to discover a huge 120 cubic square foot Yellow Jacket nest below deck and you had to use your Jedi light sabre to ward them off until you could activate a thermo-nuclear device to destroy them all in an instant!... we would need a video of that however.