Ketch mizzen sheet. So on a ketch, the dual purpose of the mizzen sail is to both propel and balance the vessel, while on a yawl, the smaller mizzen mainly serves the purpose of trim or balance. Yawls tend to have mainsails almost as large as those of comparable sloops. A ketch may be distinguished from a cutter or a sloop by virtue of having two masts rather than one, though a ketch with two foresails is sometimes called a "cutter-rigged ketch". Both the ketch and the yawl differ from the two-masted schooner, whose aft mainmast is taller than the foremast.
Jack Ketch in 1828. He is mentioned in the Charles Dickens novels "Oliver Twist", "The Pickwick Papers" and "David Copperfield" and in the C. M. Kornbluth science fiction story "The Marching Morons" (1951). More recently, Jack Ketch plays a role in Neal Stephenson's 2003 and 2004 volumes "Quicksilver" and "The System of the World", the first and last volumes, respectively, in his "The Baroque Cycle" series (though the last volume is set in 1714, well after the death of the historical Jack Ketch.) A Jack Ketch character appears in Neil Gaiman's "The Graveyard Book". Jack Ketch is featured as a non-speaking character