The cockpit floor I'm making out of 3/8" ply. I'm also making a grid for it out of 3/8" and 1/4" ply. I know how chaotic it can be in my cockpits so I want the floor to be pretty tough. The whole boat has to be built "Dan proof". Dan is one of my regular crew and he's a big strong guy--like 8 feet tall! He will be a key player in keeping this boat on its feet, but he doesn't always move around gracefully (sorry Dan, but you're no ballerina :)) and I don't wan't him suddenly disappearing through the floor either! It turned out strong-and fairly light. I think once it is all bonded, and glassed it should hold up well!