In
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 chosen cou ...
, a cunningham or cunningham's eye is a type of
downhaul The downhaul is a line which is part of the rigging on a sailboat; it applies downward force on a spar or sail. The most common downhaul on a modern sailboat is attached to the spinnaker pole, though this may be referred to as the foreguy in some r ...
used on a
Bermuda rigged 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 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 or
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 (windsurfi ...
below the
foot 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 meta ...
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 th ...
, 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
Draft, The Draft, or Draught may refer to:
Watercraft dimensions
* Draft (hull), the distance from waterline to keel of a vessel
* Draft (sail), degree of curvature in a sail
* Air draft, distance from waterline to the highest point on a vesse ...
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