A dry tree Paired-Column Semisubmersible (PC-Semi) platform and a Deep Draft Semisubmersible (DD-Semi) have been sized with the same topside payloads, SCRs and TTR tensions but different tensioner systems. The PC-Semi adopted a Spar type off-the-shelf tensioner with 28 ft stroke while the DD-Semi employed a longer 35 ft stroke tensioner. The stroke range is different for each type of tensioner and it is assumed that each TTR has the same vertical stiffness at nominal position. Both hull configurations have features of quayside integration and feasibility of dry transport with entire topsides. Central Gulf of Mexico (GoM) environmental conditions are considered for both hulls.
Characteristic responses consist of five portions: the first are motion RAOs and extreme wave frequency motions; the second are downward velocity at SCR porch and particle velocity at wellbay center; the third are acceleration RAOs and extreme accelerations at upper deck; the fourth are wave upwelling RAOs and maximum wave upwelling, and the fifth are shear forces and pry/squeeze RAOs and extreme loads. The comparison results of the PC-Semi and DD-Semi on characteristic responses are addressed and highlighted.