Three sheets to the wind: This nautical expression is not based on sheets meaning sails but rather on the meaning of sheet as a rope attached to the lower corners of a sail that controls the angle at which it is set, according to Brewer’s Dictionary of Phrase and Fable and other sources. The expression famously appears in Charles Dickens’s Dombey and Son: ‘Captain Cuttle looking, candle in hand, at Bunsby more attentively, perceived that he was three sheets in the wind, or, in plain words, drunk.’
DRUNK: The Definitive Drinker’s Dictionary by Paul Dickson