Shallow Water Effect on Hull to Rudder Interactions between Two Ships Alongside

Ship is under way side by side in close proximity to the other ship in the case of meeting/overtaking in a narrow waterway or ship to ship transfer operation. Since it is required to understand the hydrodynamic force characteristics for safe navigation, a lot of studies on them have been done so far. However there have been few studies on the hull to rudder interactions between two ships alongside except for the previous study by authors.1) This study is a continuous work and the shallow water effect on them is discussed. Captive model tests were conducted in shallow water, i.e. the depth/draft ratio 1.2 and 1.5, with variations in the lateral clearance between hulls, hull drift angle and rudder angle. The authors found, for example, when a ship steered, the lift interaction force acted not only on the self-ship but also on the other ship moving side by side in close proximity. It turned in the opposite direction and its acting point was also shifted with decrease of water depth. The experimental results were compared with the numerical analysis based on a nonlinear lifting body theory and it was able to capture the tendency of the shallow water effect on those hydrodynamic force characteristics.