Abstract: A deepwater windpower plant (DWP) has a tension leg-type floating platform with an evacuable base for adjusting its buoyancy for installation at ocean depths ranging from 40 meters up to 1.5 kilometers and more. The DWP has a typical offshore wind turbine assembled close to shore which is then towed to a desired installation site on the ocean, and held in place by a gravity anchoring base (GAB), to which an evacuable portion or space of the DWP platform is anchored. The GAB has upwardly extending mooring tethers and a power cable which are brought to the ocean surface by attached buoys. The GAB is sunk to the ocean floor at the installation site under controlled conditions so that the GAB lands flat on the ocean floor. As the GAB sinks to the ocean floor, the mooring tethers and power cable are pulled to the surface by their respective buoys. The GAB is loaded with heavy ballast material that can be dropped from barges on the ocean surface into the upwardly open GAB below the barges.