C-Flex hull

Haven't seen any mention of C-Flex for a while, apparently it still exists, still made by the original company:

C-Flex

It's a fiberglass planking material - long rods of fiberglass held together in a fabric matrix. So you get "planks" of the stuff, several feet long and a few inches wide and put them over your mold frames. The rods give it enough strength to span the frames and tend to nicely fair out.

That page above has a link to a manual for working with it, and if you google "c-flex fiberglass" and look at images, there are a few that give you an idea of what the stuff is like. The pictures that look the most useful to me are the smallish black&white pictures from the Glen-L boat plans web site (another name I haven't seen for a long time!).

One of the listings for Flying Lady says:

I would assume that they put a layer of C-Flex and fiberglass over the outside of the hull, but the way that ad reads, it almost sounds like they did it on the inside.