 Structures may be fixed in place in the seabed—as is the case for piers, jettys and fixed-bottom wind turbines—or maybe a floating structure that remains roughly fixed relative to its geotechnical anchor point.Undersea mooring of human-engineered floating structures include a large number of offshore oil and gas platforms and, since 2008, a few floating wind turbines.Two common types of engineered design for anchoring floating structures include tension-leg and catenary loose mooring systems.