I worked for Jay in two segments for close to four years and I assure you that it was Jay's standard way of coming up with a "new" hull. He would change the bow and the transom but the rest was usually a "spalsh" of an existing design that he scaled up or down to suit. Jay justified it by saying that this way he knew the boat would work. Go back and look at a lot of Jay's early designs. You will see down in the right hand lower corner the initials "RHP". That's me. I was there.
We all have our own way of designing boats and Jay's way has worked for him so Kudos to him for that. I like Jay's work and I agree his boats are unique at least cosmetically. But for me, part of my make up that said to me, "You can do better" was the arrogance of starting each new design with a blank sheet of vellum.
To each his own.