摘要：Nowadays the larger tanker ships sometimes face the difficulty to access the port inside since the infrastructure such as water depth, berth length and port area is not suitable for the ship size. Ship-to-Ship (STS) transfer either offshore or inshore could be helpful for that problem, which is known as a lightering operation. In the stage of berthing, the larger ship maintains the steerage on a constant heading, and the smaller ship maneuvers alongside. On completion of mooring, a cargo transfer starts while two ships are underway, anchored or drifting. Although STS operation might be established, two ships in close proximity have high potential collision risks so the hydrodynamic force characteristics including the interaction among hulls and rudders should be more examined.In this study, those characteristics between two Wigley parabolic hulls were investigated experimentally and numerically. Captive model tests were conducted to measure the hydrodynamic forces acting on two hulls and two rudders, changing lateral and longitudinal distance between ships, hull drift angle and rudder angle. The experimental results were compared with numerical analysis using a nonlinear lifting body theory. We found that when a ship steered, the circulation was induced to the other ship hull due to the interaction. It results in causing the additional lateral force and moment. When a ship is in oblique towing, we see the other ship hull suffers from the interaction force and moment and they change complexly depending on the hull drift angle. Those interactions become stronger as two ships become closer. The lifting-body based calculation method can capture such hydrodynamic force characteristics between two ships with a rudder.
