The invention is directed to a single moored offshore marine turbine assembly having a central control vessel which includes a main vessel tethered to a control buoy. The main vessel having a first cap, a corresponding second cap and a tubular shell positioned between both the first cap and second cap. The tubular shell contains one or more vertical partitions to assist in ballasting. The control buoy includes a compressor and an air conduit which forces air into the main vessel through a manifold. A hollow suction caisson affixes the central control vessel to the ocean floor. A taut line mooring secures the suction caisson to the main vessel. Electricity is generated via a turbine shroud assembly having a conical shroud and a hydro-turbine. By attaching a plurality of turbine shroud assemblies in series via cables, a horizontal turbine array is formed resulting in a simple, economical and safe layout.