Hi milos, plywood used for kayak on pictures and videos is a regular one. this same non waterproof plywood is used in doubletrouble too. and for more then a 3 years. If you want to build a boat, we have what you need. chesapeake light craft is your source for boat kits, kayak kits, boat plans, and boatbuilding materials.. Freedom kayaks ltd produces bespoke, british hand crafted composite kayaks and paddles.