Patent ID: 6997132

Claim:
A semi-submersible offshore vessel comprising: a substantially ring-shaped lower pontoon; starboard and port forward columns, extending upwards from said lower pontoon; starboard and port aft columns, extending upwards from said lower pontoon, and an upper deck structure connecting upper portions of the columns with each other, said upper deck structure having a substantially rectangular module recess for receiving one or more operation modules, for example carrying hydrocarbon processing equipment, wherein said upper deck structure is generally C-shaped, having a forward torsion box extending transversally between the starboard and the port forward columns of the semi-submersible offshore vessel, and two mutually parallel longitudinal side beams extending aft from the starboard and port forward columns to the starboard and port aft columns, respectively, in such a way that said module recess exhibits an open aft end, the width of which substantially corresponds to the width of an operation module, and that said module recess is delimited in a downwardly direction by a substantially planar module deck which extends between and interconnects said longitudinal side beams.