Insailing, acunningham orcunningham's eye is a type ofdownhaul used on aBermuda rigged sailboat to change the shape of a sail. It is named after itsinventor,Briggs Cunningham, a victoriousAmerica's Cupskipper andyacht builder.[1]
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 themast orboom below thefoot of the mainsail. It is then passed through acringle in theluff of the sail near the foot but above thetack, and then led down on the other side to a fitting on the mast, boom or ondeck.
The tension in the luff of the sail is adjusted using a combination of thehalyard 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 maximumdraft 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.[2]