Hi Dimitru, first of all, sorry for my late reply - i was on a trip and just manage to get back at home. Yes, PVA and polyester resin are bad substitute in this kind of boatbuilding - they try to shrink when cures and bend plywood. When this is impossible, they just delaminates from the surface. And they do not have such a waterproofness, strength and adhesive to the wood like epoxy. Thanks for the info and photos in the link! Have a fun in building and using the kayak!
Hi Dimitru,