Forces on sails to stay within the limitations of a craft's stability and power requirements, which are functions of hull (for boats) or chassis (for land craft) design. Sails derive power from wind that varies in time and with height above the surface. In order to do so, they are designed to adjust to the wind force for various points of sail. Both their design and method for control include means to match their lift and drag capabilities to the available apparent wind, by changing surface area, angle of attack, and curvature. Wind speed increases with height above the surface; at the same
Man-of-war Man-of-war The man-of-war (pl. men-of-war; also man of war, man-o'-war, man o' war, or simply man) was a British Royal Navy expression for a powerful warship or frigate from the 16th to the 19th century. The term often refers to a ship armed with cannons and propelled primarily by sails, as opposed to a galley which is propelled primarily by oars. The man-of-war was developed in Portugal in the early 15th century from earlier roundships with the addition of a second mast to form the carrack. The 16th century saw the carrack evolve into the galleon and then the ship