A device, usually with mechanical advantage, used to pull the boom down, flattening the sail.

A rope used to keep a gaff from sagging to leeward. On a schooner's foresail a block is lashed to the mainmast head, through which the vang is rove and made fast to the fore gaff end; the fall of the rope leads to the deck. In square-rigged ships vangs are generally used on the spanker gaff. Sprit sail barges also use vangs.