A New Monohull Form Development as Applied to an Offshore Drilling Unit

A new monohull form has been developed specifically in an attempt to combine certain advantages of the semisubmersible and conventional ship shape drilling vessel into a vessel of unique design. The new hull form represents a well-balanced workable design particularly suited to ships where seakeeplng, environmental operability and overall cost-effectiveness are the primary requirements. The basic advantages of the new monohull form when applied to a drillship are as follows:excellent motion characteristics (motions approach those of a comparable semisubmersible);economical advantages in hull fabrication due to the use of straight line framing and developable surfaces;high payload-to-displacement ratio compared with a semisubmersible;large usable deck area compared with a conventional drillship;safety—substantially improved intact stability characteristics, thus incorporating a major advantage of a semisubmersible; anda hull configuration that provides good structural integrity when compared with a semisubmersible.