A boat or yacht that is cat-rigged has a single mast, stepped well forward, carrying a single fore and aft sail, behind the mast. A boat that is cat-rigged can also be described as having a Una rig.

Laser dinghies are cat-rigged, as are Finn dinghies, Optimists, many Freedom Yachts and many traditional fishing vessels.

Also cat-rigged are catboats,^[1] a traditional style of wide-beamed, shallow-draft boat, typically gaff-rigged with a centreboard. Formerly common on the East Coast of the United States they are more commonly seen as dinghy-sized open daysailers and class racers.

The terms cat-rigged, and catboat, should not be confused with catamarans. Catamarans are not related to the term cat-rigged, though catamarans can be cat-rigged, if they have a single sail and no jib.

The term 'cat' may come from the 'cat head', a protruding cross beam, not far behind the bow, or head, of a sailing ship, to which the anchor was attached when the vessel was preparing for sea. The mast of a cat-rigged boat is stepped near the point where the 'cat head' would be.

• Glossary of nautical terms (disambiguation)

• Grayson, Stan (2002). Cape Cod Catboats. Marblehead, MA: Devereux Books. ISBN 1-928862-05-5.
• Leavens, John M.; Chapelle, Howard I. (September 1991). The Catboat Book (paperback). Middleboro, MA: Catboat Association with Intl Marine Publishing Co. pp. 160. ISBN 0877423148. ISBN 978-0877423140