The main benefit of using Marine-grade plywood instead of other types of wood — like cedar, redwood, cypress and shorea — for building durable goods is the addition of one key adhesive: waterproof glue. If this type of plywood becomes exposed to moisture or high temperatures, waterproof (and boil-proof) glue will help to ensure the plies won’t divide into smaller layers or “delaminate.” Thus, if a boat hull’s protective layer or “finish” becomes damaged and the plywood gets slightly wet or even immersed, the wood won’t be affected.