The instant invention is a deck barge or other vessel formed using a core of styrofoam members stiffened by fiberglass cladding with said styrofoam/fiberglass core being partially clad in concrete, which concrete is reinforced with “L” or “U” shaped rebar over/around corners and which concrete is also sheathed on its exterior and interior sides by fiberglass matting that is concrete saturated during the process in order to produce a simple, easily manufactured design that is unsinkable, inexpensive, and carries substantial weight for its size. In the preferred embodiments, the concrete cladding entirely covers the port and starboard sides as well as the top/deck of the vessel and portions of the bottom.