When a ship sails in a narrow waterway or a canal, bank suction causes the ship to move toward a sidewall, while it pushes the bow of the ship to the opposite side generally. In order to keep a ship on course, it is required to understand the hydrodynamic forces acting on a ship hull considering parameters such as drift angle, the width of a waterway, distance between a ship and a sidewall and so on. This paper approaches the bank suction effect on ship manoeuvring motion by model experiments. Captive model tests were performed to understand the bank suction effects in several conditions of the width of a narrow waterway. Hydrodynamic forces were measured for two types of cargo ship models (coal carrier and cargo carrier) in order to examine the influence of hull forms on this phenomenon. Drift angle, the width of a waterway, distance between a ship and a sidewall and water depth were selected as parameters which would have influence on lateral force and yawing moment. Measured results shows that the bank suction tends to become larger, as the water depth becomes shallower, the canal width becomes narrower, and distance between a ship and a sidewall becomes closer. Based on the analysis of the measured hydrodynamic forces, the authors propose brief approximate formulae for estimating the bank effect using the above mentioned parameters. The approximate formulae would be useful for modeling ship motion with drift angle and counter rudder in various width of a waterway.
展开▼
