This is a commercial vendor of a folding boat… looks to use a rubber type hinge. Might be of interest if you don’t want to build your own.
Instaboat is the perfect portable folding boat for outdoors enthusiasts. This foldable boat is lightweight, durable, and can be assembled in 2 minutes. This boat adapts to all recreational vehicles and is easy to carry. Very stable and safe to use, it is unsinkable, even when filled with water.