A modular boat hull including bow and stern sections and at least one center section. Preferably these modular sections are rotomolded thermoplastic parts. These modular hull sections can be quickly assembled by coupling a center section to the bow section and then coupling the stern section to the center section. To increase the length of the hull, additional hull center sections can be added as desired. The modular hull sections are coupled by locking arrangements and then secured by installing a support member which bridges the joints between the gunwale sections of adjacent hull sections. Each modular hull section has a lattice for supporting a deck. The deck can be a single piece installed inside the assembled hull. Alternatively, the deck may be modular.