A staysail is a type of sail that is set between the foremast and mainmast of a sailing vessel. It is usually triangular in shape and is used to increase the power of the vessel when sailing close-hauled. The term 'staysail' is derived from the fact that it is attached to the stay, which is a rope or cable that runs from the masthead to the deck. The JIB is another type of sail that is also triangular in shape and is set forward of the foremast. It is used to increase the power of the vessel when sailing close-hauled and is often used in combination with the staysail.