WISH program has been extended to the hydroelasticity problem of global ship structure. Very recently, springing and whipping are of great interest due to the potential risk of fatigue damage. As the size of ships or offshore structures is getting larger, the natural frequency of hull-girder vibration tends to move to lower frequency range. Moreover, faster forward speed makes the encounter excitation frequency of ocean wave to move much closer to its natural frequency of structural vibration, consequently leading to the higher chance of resonance between the two even under linear wave regime. The most critical situation is the case of ultra-large container carriers. Unlike other types of vessel, container carriers have very low torsional natural frequencies due to large hatch openings on deck.