PURPOSE: A composite hull structure for a small ship is provided to prevent a rolling phenomenon and a pitching phenomenon by connecting branch grooves to a mounting groove formed on the bottom of a hull. CONSTITUTION: A composite hull structure for a small ship comprises a streamlined stem(20) and a plate shaped stern(30). The streamlined stem is formed in one side of an underside of a hull(10). The plate shaped stern is formed in the other side of the underside of the hull. The streamline stem is formed into a shape in which branch grooves are bidirectionally branched by a V-shaped branch part(21). A reversed U-shaped mounting groove(11) is formed on the underside of the hull from a point where the ends of the branch grooves are met to the stern. The reversed U-shaped mounting groove is upwardly recessed to divide the underside of the hull into two parts.
