I'll go along with the plywood , light, quick and works well. I don't go along with the marine grade as it is the same as exterior plywood, except it has no voids, where-as ext grade ply will have a few. The glue in marine is exactly the same and the wood is exactly the same as marine grade except for the voids, but costs 2 times as much. The advantx works just as well as plywood, but is a bit heavier. Later, Nat