: Looking for any information anyone might have or references you
: might know of to the History of Fuselage Frames in boats. I am
: writing an article and would like to have some facts. About all
: I have found it is that is probably started in the early 50's
: maybe late 40's after the war, when cheap plywood became
: available. Past that I don't have a lot more info.

I always start with Wikipedia:

The first workable folding kayak was built by Alfred Heurich in 1905, a German architectural student. Heurich paddled his creation on the Isar River near Munich and took out a patent on the design, called the Delphin (German: Dolphin), the following year. The Delphin had a bamboo frame with a sailcloth hull stretched over it. It could be folded up and carried in three bags, each weighing less than 4.5 kg (9.9 lb).
The folding kayak was made commercially successful by Johannes Klepper, whose factory was at Rosenheim, Germany. Klepper kayaks were very popular for their compact size and ease of transport. Klepper's Faltboot was introduced in 1906, many years before hardshell boats were commercially produced