Hydrodynamic Response and Mooring Loads of Side-by-Side Moored Ships at a Quay Using AQWA

Side-by-side mooring alongside a quay is an effective strategy to enhance berth utilization and port efficiency. However, in confined waters, hydrodynamic interactions among adjacent ships and the quay wall can significantly alter ship motions, wave loads, mooring tensions, and fender reactions, thereby affecting operational safety. In this study, frequency- and time-domain numerical models of side-by-side moored ships at a quay were developed using the ANSYS AQWA 2025 R1 hydrodynamic analysis software (hereafter AQWA). The S175 and Wigley III hulls were selected as representative vessels. After model validation and mesh independence analysis, the hydrodynamic response of the inboard ship was examined under varying wave headings, water depths, quay boundary conditions, and outboard ship scales. Mooring loads were further analyzed under regular waves, irregular waves, and combined wave–current conditions. The results indicate that side-by-side mooring significantly modifies the sway, heave, and roll responses of the inboard ship. While the outboard ship generally provides a shielding effect, local response amplification may still occur within specific frequency ranges. The wave heading, shallow water, and quay wall effects play dominant roles in redistributing wave excitation forces, added mass, and radiation damping. Time-domain simulations reveal that ship-to-ship mooring lines S2 and S3 are the critical load-bearing components, especially under beam waves and certain oblique current directions. The use of polyester mooring lines effectively reduces peak tensions in critical lines but may increase fender reactions. These findings provide a reference for hydrodynamic safety assessment and mooring optimization in side-by-side berthing operations.