The
hull was most like built in two halves and joined at the centerline when pulled from each half
mold. It's pretty common for boats of that time to be built this way.
I can't tell from the photos, but I would grind down and retape the pieces together. I'm sure it's still fine on the inside, it's just this outer layer that had issue - and hopefully just the transom. Two layers of 8" and 6" of 1708 should be good.