Foundation device for an offshore wind turbine tower

A device for supporting a wind turbine tower, the device comprising a first body, a support body attached to the first body, a second body and a plurality of legs attached to the second body, wherein

• the support body has a cylindrical interior which defines a tower axis and is configured to provide support for and connection of a wind turbine tower;
• the first body comprises a central portion connected to the support body and a plurality of hollow arms, connected with the central portion, wherein each hollow arm extends radially from the central portion and comprises a first surface perpendicular to the tower axis and a second surface parallel to the first surface, wherein the first surfaces of the hollow arms are contained in a first reference plane and the second surfaces of the hollow arms are contained in a second reference plane, wherein the first reference plane is further from the second body than the second reference plane;
• each hollow arm comprises a through-hole which extends from the first surface to the second surface, wherein the through-hole is configured to allow a leg to pass through the through-hole;
• the first body has a volume and a weight configured to provide, when empty, a buoyancy of at least 20% of the weight of the entire device, the weight of the first body being less than 8% of the weight of the entire device;
• the first body has a first ballast management element to selectively allow the entry and exit of water into/out of the first body;
• the second body has a first surface and a second surface, both parallel to the first and second reference planes, wherein the first surface is closer to the first body than the second surface;
• the second body has a ballast management element to selectively allow the entry and exit of water into/out of the second body;
• and
• the legs and/or the first body have a locking system configured to lock the relative position between the legs and the first body.