The present invention generally provides mold modules for constructing boat hulls, methods of constructing boat hulls using the mold modules, and hulls constructed using the mold modules. The modules may be adjustable, and may be included in a kit for building the hull of many boats of different dimensions but generally the same shape. Each mold module generally comprises a mold in a shape complementary to that of a portion of a boat hull, and an edge mold to form the edge of the hull part formed by that mold module. A mold module according to the present invention may also comprise one or more mold adjustment areas, and calibrators for selecting the boat hull dimensions. Methods for using the aforementioned mold modules generally comprise steps of molding hull parts, removing them from the mold modules, aligning them and finally attaching them together.