SEMI-SUBMERSIBLE VESSEL

摘要

A semi-submersible unit for use in offshore operations which has a significantly reduced susceptibility to heave motions in wave periods which are most likely to be encountered during practical operation conditions. The unit consists of a lower hull or lower hulls (4) supporting vertical buoyant caissons (6) which also support an upper deck or platform (12) which supports and is supported by a centrally disposed, large diameter buoyant caissons which contributes a significant portion of the total water plane area of the vessel (2) when it is submerged to its operational draft. The vessel (2) may be configured for offshore drilling operations, diving support, and various other offshore support functions. When configured for the offshore drilling operations, the central column (24) serves as a buoyancy chamber and as a primary storage chamber for tubular products (32) which are associated with the drilling function. This clears the deck (12) of the vessel (2) for other operations and introduces a less hazardous method for handling tubular products (32) than in previous designs. The central caisson has an interior annulus (28) which is open both to the drill floor and the sea through which operations may be carried out. The semi-submersible vessel exhibits significantly less heave in operational wave conditions than existing semi-submersibles of similar water plane area and displacement.