Cunningham downhaul, luff stretchers

In this category you can purchase mooring lines that are ideal for use as a luff stretcher.

Named after its inventor, America's Cup winning captain Briggs Cunningham, the luff stretcher is also referred to as a Cunningham stretcher or simply Cunningham. The Cunningham tensioner is used in sailing as a trim line with which the luff tension on the mainsail can be adjusted. By adjusting the downhaul tension you can influence the overall shape of the mainsail and optimize the trim for course, wind, sea state and wind conditions.

Tightening (adjusting) the downhaul will result in a flatter sail profile. At the same time, the belly (i.e. the greatest depth of the mainsail profile) moves forward towards the mast. In addition, the leech opens, which reduces weather protection. Loosening (relaxing) the Cunningham tensioner has exactly the opposite effect:
a more cambered mainsail profile, at belly shifting and leech closing.

Alternatively, the luff stretcher can also be adjusted via the halyard. The main advantages of the Cunningham tensioner over the halyard are that it is quick and easy to use, requires significantly less effort and has a positive effect on the leech. Thus, the luff adjuster is ideal for fine adjustment of the mainsail trim.

The rule of thumb for adjusting the Cunningham extensor while sailing is:

• the less wind
• the greater the course to the wind (the further behind the wind) and
• the stronger the sea,

the more relaxed the Cunningham extensor is. The Cunningham tensioner is set to its maximum when the wind is upwind, the wind is strong and the waves are still relatively small.

The following items are recommended for use as a luff stretcher / cunningham.