Study on the squat of extra-large scale ship in the Three Gorges ship lock

Aiming at determining the controlling standard of extra-large ship entering or exiting the Three Gorges ship lock of China, the maximum squat of typical ships with physical model test was examined in this study. Physical model tests include hydraulic and 5000 t ship model tests at the scale of 1:36.3, with the purpose of obtaining the squat of ships entering or exiting ship lock at different depths, draft and speeds. Based on the theoretical analysis and previous achievements, this study advanced the mathematical models to estimate the maximum squat of ship driving in special restricted channel. For the typical ships, it is reliable to take the ratio of water depth to draft (i.e., H/T≥1.6) as controlling standard of ship entering or exiting ship lock. The results showed that the squat obviously increased with the ship passing by moored ships in the lock. The speed of typical ship with different lanes should be slower than 0.5 m/s to ensure the safety when other ship berthing in ship lock, which matched well with the observations. The proposed formula is feasible in scientific method, reasonable conclusion with accurate calculation, and therefore can be applied to the squat studies.