RoboTUG is a subproject of the joint research project FernSAMS.

Background

The ever increasing size of vessels and the remote-controlled or autonomous operation of ships are two major research fields in the maritime industry. To maneuver the ultra-large container vessels inside the existing harbour infrastructure is a challenge for masters, pilots and tugs. Modern ship handling simulations offer the possibility for all involved persons to practice and optimise the maneuvering in restricted areas like harbours under consideration of interaction effects  between oceangoing vessel and tugs. Therefore, extensive and precise data about the maneuvering characteristics of all vessels participating in the maneuver is needed. These informations should be developed thoroughly to ensure the validity of the simulator results. Even more when it comes to remote-controlled or autonomous ships, a large database is the basis for all decisions taken by the system.

Computational Approach

Modern CFD methods offer the possibilty to generate maneuvering coefficients for all types of ships. Also detailled informations about the interaction effects, when it comes to nearby operations or propeller-ship influences, can be considered. These informations are essential for the proper simulation of harbour maneuvres. A RANS based numerical solver is used to compute a full set of hydrodynamic maneuvering coefficients for a Voith-Schneider propelled RAVE-tug. Furthermore the focus of the research project is on the computation of the hull-hull- and propeller-hull interaction effects which increase during the close-by maneuvers in harbours. In the research project the commercially available solver STAR-CCM+ is used for the computation of the flow field.

Application

For a 70 tons bollard pull harbour tug, extensive data about it‘s maneuvering characterisitic is computed. The tug considered in the study is a 35 meters RAVE tug, designed by Robert Allan and driven by two in-line Voith-Schneider propellers (VSP). An additional focus is on the consideration of the interaction effects with a 14000 TEU container vessel during typical harbour maneuvers at about five knots. The well-known Duisburg Test Case is selected to represent the oceangoing vessel. Major ship-to-ship effects occur during close-by operations (line handover) especially at the bow of the oceangoing vessel (left picture below) and major ship-propeller interactions when the tug‘s propeller slipstream hits the vessel‘s hull (push/pull operations) as shown in the right picture below.