The patented EnergySail is a rigid sail and wind assisted (or sail assisted) propulsion device designed by Eco Marine Power that allows ships to harness the power of the wind and sun in order to reduce fuel costs, plus lower noxious gas and carbon emissions. The patented EnergySail is unlike any other sail - it can be used even when a ship is at anchor or in port and has been designed to withstand high winds or even sudden micro-bursts. A variation of the EnergySail that is suitable for Unmanned Surface Vessels (USV's) and smaller ships such as passenger ferries or fishing vessels is also being developed.