US Patent 7275891 Apparatus for controlling underwater based equipment

The apparatus may include a space frame on which is mounted at least one hydrofoil for generating positive or negative lift. The frame is attachable to underwater equipment such as a turbine. The hydrofoils are adapted to produce negative lift when a flow of liquid passes over them and so in use cause the apparatus and attached equipment to sink to the seabed. The flow of water over the hydrofoils continue to produce negative life and so maintain the apparatus on the seabed. In certain embodiments, the hydrofoils can typically be set to a passive configuration in which they flip over when the current flow changes direction. Furthermore, the hydrofoils are selectively rotatable to provide an angle of attack such that they may be adapted to provide positive lift when it is necessary to remove the apparatus from the water.