Well the MK III has the same hull as the MK I and II. New materials and methods allow it to be built lighter while keeping it strong, and going back to a one-piece hull removes the deck-lip. The original 5.0 Mk I had a one-piece hull with oval sections of epoxied-plywood making up large sections of the deck. I believe it was the first-ever catamaran with a one-piece hull design. He had one for sale at the factory in St. Pete when he installed the Dotan rudders on my 5.7M.

So that would be why it's 3" too long to be a FH16- the hull design isn't entirely new. However, the "old" hull design is an excellent design and still very competitive.