I designed and built this folding paddleboat in the 1980's. Like similar folding paddle boats it has a 4-part ladder-frame, 6 longditudinal dowels (each in two parts), 6 ribs and a wooden rim around the cockpit. Length 410 cm, beam 45cm, weight 20kg. The long dowels are about 200cm long so it can be carried on a bicycle with panniers and a rucksack (one of the design parameters).
Since I do not own a folding bicycle, I cannot be completely amphibious and transport the bicycle on the paddle boat. (Some people manage this with a folding bicycle and a folding trailer. It certainly makes planning a trip very flexible.) In the meantime I find it more convenient to transport it to one of Berlin's many lakes and waterways that can be reached by public rail transport: U- and S-Bahn.
The skin is made of the same plasticised tarpaulin material that is used to cover the trailers of heavy goods vehicles. The material was laid over the completed frame and cut to size, stuck together with impact adhesive (applied to both sides of the joins) and then sewn where necessary with a treadle Singer sewing machine using a sharp-sided "leather" needle. There are two layers of material on the lower hull and three layers under the keel and around the stem and stern.
To set it up, the assembled frame is pushed into the front half of the skin, extended and fastened, and then the rear half of the skin is closed up over the top of the frame with a heavy-duty plastic zip-fastener. The parts of the frame are colour-coded; it takes about 20 minutes and some cursing and swearing to assemble. It is usually configured and used as a single-seater but it can also be re-arranged to accomodate two not-too-heavy persons who are good friends. In this case the steering gear, with its pedals, is omitted and is, any case, not really essential.