SOLUTIONS TO TORSIONAL MOMENTS, HOGGING, AND SAGGING IN ULTRA LARGE CONTAINER VESSELS (ULCVs) AND SIMILAR SHIPS

ABSTRACT Ultra Large Container Vessels (ULCVs) present a fundamental structural paradox in naval architecture: they are "open-top box structures" lacking a continuous strength deck. Consequently, dynamic torsional moments and shear stresses induced by oblique and head seas concentrate severely along the hatch corners and upper torsion boxes, leading to structural cracking and fatigue over time. This paper introduces two novel structural paradigms designed to supplement traditional 90° orthogonal framing systems: Diagonal Reinforced Arched Frames for torsional vibration/energy damping and Diamond Shear Relief Structures for longitudinal shear load redistribution during hogging and sagging. Furthermore, the paper analyzes the hydrodynamic and structural trade-offs between flat-bottomed ("box-shaped") hull forms and rounded bilge profiles, highlighting the impact of roll acceleration on lashing system failures and container losses at sea.