On the power savings by an auxiliary kite propulsion

A performance study of auxiliary wind propulsion for commercial ships by means of a traction kite is presented. It is not focusing on practical design aspects of such a system and therefore not concluding on practical feasibility, rather it gives an indication of the amount of fuel saving in various environmental conditions assumed that the system is working practically. An estimate is presented of the delivered traction force of a kite. Depending on the apparent wind direction and wind speed, this kite force will cause a drift angle of the ship, resulting in additional resistance. This effect is taken into account by simultaneously solving the force balance in longitudinal and lateral direction and the yaw balance. Finally, in order to calculate the effect of auxiliary kite propulsion on the fuel consumption at constant ship speed, the performance in off-design conditions of the existing propulsion system is considered. Results of a case study are presented showing the relative fuel saving as a function of wind speed and wind direction relative to the sailing direction.