Huang P.Y.Lin Z.-Y.Lai Y.-W.TSUNG-YUEH LIN2026-03-242026-03-24202510234535https://www.scopus.com/record/display.uri?eid=2-s2.0-105029554264&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/736640The equations of motion for a ship can be established using measurement results from captive model tests. This study experimentally investigates the hydrodynamic forces acting on a ship hull under various captive motion tests in calm water to determine the hydrodynamic derivatives. Experiments were conducted using a container ship model to perform OTT (oblique towing test) at different drift angles and PMM (planar motion mechanism) Pure Sway tests with varying sway amplitudes. The longitudinal force, lateral force, and yaw moment acting on the hull were measured. The measured force data were applied to the equations of motion, utilizing Fourier analysis and numerical fitting to derive the hydrodynamic derivatives. This study compares the procedures and the resulting sway hydrodynamic derivatives obtained from Single Run (SR) and Multiple Run (MR) Pure Sway tests, as well as those from OTT. The results indicate that the MR method is less susceptible to anomalies in individual test data compared to the SR method. The linear sway derivatives Yv , Nv obtained from OTT and Pure Sway tests show close agreement. However, the cubic sway derivatives Yvvv , Nvvv derived from Pure Sway tests differ significantly from those obtained via OTT and results from previous studies, suggesting that the Pure Sway test may not effectively capture the characteristics associated with the cubic terms of sway velocity.falseHydrodynamic DerivativesOblique Towing Test (OTT)Planar Motion Mechanism (PMM)Pure Sway Testjournal article2-s2.0-105029554264