Abstract: The systems and methods for assembling and installing multiple wind turbines from a single vessel are provided. Generally, the different embodiments use wind turbine components on the vessel that include blades, a nacelle assembly having a rotating hub, and a tower. A Turbine Installation Gantry System (T.I.G.S.) embodiment uses a gantry system having a truss sub-structure and at least one bridge crane on the elevated vessel for assembling the wind turbine blades on board to the nacelle hub supported above the seabed. A Skidding Turbine Installation Crane (S.T.I.C.) embodiment has a rotatable crane mounted on a skidding pedestal or cantilever structure to provide full access to the vessel deck and the blades outboard of the vessel for assembling each of the blades with the assembled nacelle assembly outboard. A Turbine Assembly and Positioning System (T.A.P.S.