Offshore Drilling Systems

1,188,823. Boring earth &c. offshore floating-structures. W. G. V. DORN. 17 July, 1967 (18 July, 1966], No. 32811/67. Headings E1F and E1H. An off-shore drilling system comprises a buoy 58, a derrick and drilling rig 34 carried by the buoy, and a floating vessel 48 connected to the buoy such that vertical movements of the vessel are not transmitted to the buoy. A gimbal is used to interconnect vessel and buoy and precludes the transmission of vessel roll and pitch to the buoy. The buoy may comprise a single member with a tube extending therethrough to contain flexible conductor tube 44 through which drilling occurs, or it may comprise interconnected cylindrical members spaced about the buoy axis. The buoy is transported in a central channel 64 in the vessel and pivoted to the vertical position when over the site using water ballast to achieve the desired buoyancy. The derrick is pivoted to platform 36 and is lowered for transportation.