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. Design software: aerohydro (marine design and modeling software and services) aerologic (lofting, simulation and analysis software) aeromarine research (tunnel boat. Crochet books; crochet animal books; crochet fashion books; crochet hoem books; cross stitch books; cross stitch alphabet books; cross stitch baby chart books.