A comparative study on 10,000-DWT ship squat in an intermediate channel via numerical simulations: Self-propelled versus towing

An intermediate channel is a navigation channel connecting two or more locks or boat lifts during navigation through high dams, and the propeller effect caused by large ships is more and more obvious in the extent of their sinkage during intermediate channel navigation. Herein, the MAU4-55 propeller is retrofitted to a 10,000-deadweight tonnage (DWT) vessel. Then, the hull resistance and vertical force are compared via a physical experiment report and the determination of the open-water coefficient of the propeller. The precision of simulation is validated by comparison with the experimental data. Further, a ship self-propulsion model (body-force method) and a towing model (T) are developed, and the ship squat performance estimated using these models is compared at different ship speeds in an intermediate channel with W/B = 2 and h/T = 1.45. Subsequently, the primary causes of ship sinkage are analysed based on changes in the surface of water and bottom flow velocity. Results reveal that the towing model neglects the influence of water surface changes on ship squat caused by the propeller effect, yielding low-accurate sinkage predictions.