Just frm the pictures on the book cover, shown on his site, I'd say he was building a qui k-and-dirty multi-chine S-O-F kayak frame from low cost wood strips, and the covering it with a layer of plastic. That would serve as a plug, or male mold, on which he could lay up a few layers of fiberglass, carbon, or kevlar. The mold would be light and cheap. You could bust it up to pull it out of the completed shell.
His large open cockpits are easier and faster to make than lipped coamings--and with such a large deck opening there would be no need to make hatches.

The wasp-waist center has been seen on other designs before. I guess it works better with wide hulls--which give good stability, but are hard to reach over to get the paddle in the water.

All of these are good ideas for some people, but of course no one design suits everyone.

PGJ