sailing Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' ( land yacht) over a chose ...

, a cunningham or cunningham's eye is a type of downhaul used on a

Bermuda rigged A Bermuda rig, Bermudian rig, or Marconi rig is a configuration of mast and rigging for a type of sailboat and is the typical configuration for most modern sailboats. This configuration was developed in Bermuda in the 1600s; the term ''Marconi' ...

sailboat to change the shape of a sail. It is named after its

inventor An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an ...

Briggs Cunningham Briggs Swift Cunningham II (January 19, 1907 – July 2, 2003) was an American entrepreneur and sportsman. He is best known for skippering the yacht ''Columbia'' to victory in the 1958 America's Cup race, and for his efforts as a driver, team o ...

, a victorious

America's Cup The America's Cup, informally known as the Auld Mug, is a trophy awarded in the sport of sailing. It is the oldest international competition still operating in any sport. America's Cup match races are held between two sailing yachts: one ...

skipper and

yacht A yacht is a sailing or power vessel used for pleasure, cruising, or racing. There is no standard definition, though the term generally applies to vessels with a cabin intended for overnight use. To be termed a , as opposed to a , such a pleasu ...

builder. The cunningham differs from a typical downhaul in the way that it attaches to the sail. The system usually consists of a line which is secured at one end to the

mast Mast, MAST or MASt may refer to: Engineering * Mast (sailing), a vertical spar on a sailing ship * Flagmast, a pole for flying a flag * Guyed mast, a structure supported by guy-wires * Mooring mast, a structure for docking an airship * Radio mas ...

boom Boom may refer to: Objects * Boom (containment), a temporary floating barrier used to contain an oil spill * Boom (navigational barrier), an obstacle used to control or block marine navigation * Boom (sailing), a sailboat part * Boom (windsurfin ...

below the

foot The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg mad ...

of the mainsail. It is then passed through a

cringle A cringle is an eye through which to pass a rope. In nautical settings, the word refers to a small hole anywhere along the edge or in the corner of a sail, rimmed with stranded cordage and worked into the boltrope. Typically it encloses a metal ...

in the luff of the sail near the foot, but above the

tack TACK is a group of archaea acronym for Thaumarchaeota (now Nitrososphaerota), Aigarchaeota, Crenarchaeota (now Thermoproteota), and Korarchaeota, the first groups discovered. They are found in different environments ranging from acidophilic ...

, and then led down on the other side to a fitting on the mast or boom or on deck. The tension in the luff of the sail is adjusted using a combination of the

halyard In sailing, a halyard or halliard is a line (rope) that is used to hoist a ladder, sail, flag or yard. The term ''halyard'' comes from the phrase "to haul yards". Halyards, like most other parts of the running rigging, were classically made of ...

and the cunningham (where fitted). The primary advantage of adjusting the cunningham is the speed and ease with which the luff tension can be changed while sailing or racing. By either hauling or easing the line, the tension in the luff can be changed, thereby shifting the point of maximum draft of the sail forward or aft respectively, optimizing sail shape and thus performance. It is a fine control which is used more frequently on racing sailboats than on cruising or day-sailing boats.

References

Guide to Sail Control Part II: Mainsail Trim (All At Sea Caribbean)
{{Sail Types Sailing rigs and rigging Nautical terminology Sailboat components