Rigid sails have the potential to lower fuel consumption on powered ships by using the wind as a supplementary source of propulsive power. The amount of propulsive power that can be provided by each sail is dependent on a number of variables, which include the sail type, sail area and number of sails deployed. Since each type and size of rigid sail has its own performance characteristics, it is difficult to estimate the propulsive power that could be provided by a particular rigid sail and to make comparisons between different rigid sails. To overcome this problem, a rigid sail power profile is proposed. This power profile will outline key performance characteristics and allow comparisons to be made between different types of rigid sails.