Nice job on the boat. I did something similar to a boat last year and really had a lot of fun doing it. I used untreated plywood on mine and left it out over winter. I had the plywood painted with exterior grade paint The plywood really deteriorated fast with just one winter outside. i've since sold the boat only because I upgraded to a bigger one. So as others suggested make sure you keep it covered or inside. I'm sure if you do that it will last a long time. Makes me want to take on another project boat again.
