Since towboats are pretty much a square box type of construction, the built will be easy. In my gallery, my Oyster boat and the Albemarle are done in 1/4" Luan. Large flat surfaces epoxyed together. They were fiberglassed over on the outside and just the resin on the inside. The compound curved surfaces on the Albemarle were done with double layer planks. The ribs were done with some aircraft ply that I had laying around. Cheap and quick.