The awareness of the climate change is increasing and the effect of air-pollution is irrefutable. To decrease the emissions of large ships the required amount of fuel has to be minimized. This is done by increasing the efficiency of the engine, decreasing the hull resistance or by lowering the cruise speed. Another interesting way of decreasing the emission is by using Wind Assisted Ship Propulsion (WASP). The Turbosail is a promising type of wind propulsion for this purpose introduced by Jacques Cousteau[4]. The Turbosail is an aspirated wing which is able to generate up to 3 times more lift compared to a non aspirated wing. A lot of research has been done in order to increase the performance of the Turbosail. But this research has mainly been done on the outside of the Turbosail and the suction area is often modelled as an area with a uniform flow. In this research a model has been made in order to give insight in the behaviour and sensitivity of the suction system of the Turbosail. First the model foundation is described. A lumped parameter approach is chosen and the structure of the model is described. The model of the fan is described and after this the total model is made using Matlab Simulink. This model is made such that the number of elements (the amount of parts that the Turbosail is divided in) can be easily varied. This is done in order to perform a convergence study. Followed by a mathematical verification with carefully chosen tests the model is considered as verified. To understand the sensitivity of different parameters of the system a parameter variation is performed. Different parameters are varied and their effects are simulated. This yields insight in the sensitivity of the system and can be used in order to optimize the energy efficiency of the total suction system. Finally two possible improved designs are simulated combined with their decrease in power consumption. These results can be used for future simulations and designs with the main purpose to decrease the energy consumption of the shipping industry.