A composite hull construction includes a metallic skeletal frame of truss-like configuration including a longitudinally extending keel plate, first and second side wall structures extending upwardly from opposing side edges of the keel plate assembly, and a top wall structure extending between upper portions of the first and second side wall structures. A synthetic foam shell entirely encapsulates the side and top wall frame structures and covers the interior surfaces of the keel plate assembly. The foam shell rigidly fixes the frame members in position and increases the compressive strength of the skeletal frame to prevent buckling of the side wall and top wall structures. An exterior fiberglass skin covers the side walls and the top wall to provide a water resistant covering over the foam shell and skeletal frame. The hull further includes an integrated fire suppression system that detects heat/smoke within the hull and automatically dispenses a fire suppression agent, such as carbon dioxide to the interior of the hull.