What would you use for a ships hull? metal or non-metal?

ALEX has pretty much got. Generally large ships have steel hulls and occasionally they have an aluminum superstructure, generally high end yachts or some warships. As you approach 200ft in length FRP becomes impractical. Wood is comparable to aluminum for hulls, cold molded technique is used. But I haven't seen a ship over 180ft made of wood in some time but I am sure there are several out there.