Intoxicated When a vessel changes her tack, she staggers and gradually heels over. A drunken man moves like a ship changing her angle of sailing. (Probably from the Icelandic, snua, turn.)
“Mr. Hornby was just a bit slewed by the liquor he'd taken.” —W. C. Russell: A Strange Voyage, chap. xii. p. 25.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894