Semi-submersible
Revision as of 20:19, 16 June 2008 by 68.253.212.215 (talk | contribs)
From wikipedia
"These platforms have legs of sufficient buoyancy to cause the structure to float, but of weight sufficient to keep the structure upright. Semi-submersible rigs can be moved from place to place; can be ballasted up or down by altering the amount of flooding in buoyancy tanks; they are generally anchored by with chain, wire rope and/or polyester rope during drilling operations, though they can also be kept in place by the use of dynamic positioning. Semi-submersibles can be used in water depths from 200 to 10,000 feet (60 to 3,050 m)."
