Effect of Wind Propulsion Systems on Sail-Induced Resistance, Rudder Angle and Heel Angle for the KVLCC2 and the KCS Vessels

Abstract When equipped with a Wind Propulsion System (WPS), a ship motion includes a side velocity (drift) which is due to the aerodynamic side force generated by the WPS. This effect generates an additional resistance (sail-induced resistance) which must be evaluated to determine the net propulsive force of the WPS. The aerodynamic side force is also responsible for an increase in heel and rudder angles, which must also be evaluated to ensure that they do not exceed operational limits. In this study, these aspects are investigated for two vessels - the KVLCC2 (tanker) and the KCS (containership) - assuming they are retrofitted with a WPS. Numerical models of the ships were implemented in a ship simulator. First, following the method described by Kramer and Steen (2022), sail-induced resistance, heel angle and rudder angle are investigated using a technology-agnostic approach which consists in modelling the WPS force by a constant aerodynamic side force. It is shown that the KCS is considerably more affected by the presence of a WPS than the KVLCC2. The rudder is identified as the main contributor to the sail-induced resistance. Reducing ship speed, moving forward or downer the centre of effort of the WPS side force is shown to mitigate the impact of the WPS on the ship. Finally, the range of aerodynamic side force that can be expected for these ships is estimated based on statistical wind data and considering a rotor sail technology. Results show that the aerodynamic side force is negligible for both ships. Keywords wind propulsion; sail-induced resistance; 4 DOF; KCS; KVLCC2; rotor sail