I am trying to not be too critical but I have had the book for many years and have studied it fairly well and Jay's description of the process is waaaaaay off.
There is a wood framwork ala stipbuilding. But is has to be very undersized because of all the layers of stuff that go on top.
It's covered with strips of foam insulation. All the edges have to be taken off. I think they used a surform plane. The strips are then covered with a layers and layers of drywall compound. They use drywall compound because there is one hell of a lot of sanding involved. The plug has to be perfect both in conformity and in surface. After much sanding and filling and sanding and filling when the surface is perfect the plug is still not ready to use. It is then covered with a gallon or so of hot parafin which is rubbed into the plug and then coated with carwax.
The process of making the plug is very labor intensive. The plug is much more time consuming than laminating the hull.It is so labor intensive that it's not worth building a plug if you are only going to build one boat.
Lastly, the plug is heavy and hard and nobody is going to dig it out of the hull. The canoe's ends are left open so the hull can be pried off the plug.
If there ever was a back breaking and unforgiving method of building a boat this is it.

: Having not read that book I rely on your description below. That sounds like
: they are building a plug out of the strips then discard the plug and are
: left with the canoe shell. That's fine but the foam is not part of the
: finished product, it seems.

: "Foam core" has a very different meaning in kayak hulls though -
: the "foam" is not the squishy type as in minicell and it is
: sandwitched b/w layers on both sides.