Cunningham/Downhaul The Cunningham (named after the inventor of the control) is just another name for the downhaul. Pulling down on the forward edge (luff) of the mainsail can make a dramatic change in the location of the draft in the main thus allowing the mainsail to become more efficient in a wider range of wind strengths. Sail makers typically put grommets above the tack of mainsails allowing sailors to run lines through them and easily adjust luff location.


tension and draft


Pulling the Cunningham/Downhaul on will


tighten the luff and create a vertical


Forward Draft


“gutter” near the front of the sail. Because the leading edge of the sail is attached to the mast, the cloth on the aft side of the mast is pulled forward. Earlier we learned that the depth in a sail is its “draft.” When the sail cloth is pulled forward, the deepest area of the sail (the “point of maximum draft”) moves forward too. Therefore, pulling down on the Cunningham/Downhaul moves the draft forward.


Tighten Cunningham


TEACHING TIPS: Position your students behind a boat so that they are directly “in line” with the boom.


Dramatically pull on the cunningham. As the draft


moves forward, have them watch the top batten ease open to leeward. Release the cunningham. As the draft moves aft, have them watch the leech hook to windward.


Full Length Battens Some boats have battens that extend from the luff to the leech of the main. These are called full length battens. The depth of the sail can be altered depending on how tightly the batten is compressed into its pocket. This can dramatically be shown by letting your students hold a batten between their palms and moving their hands toward each other. The more the batten is compressed, the more it will curve and force more draft into the sail. Some boats will have a single full length batten in the top pocket. Others, like catamarans or big roached mainsails, may have multiple full length battens throughout the sail.


Power E Fuller sail shape adds power E Increase batten tension slightly


n tension slightly 42


Depower E Flatter sail shape reduces power E Reduce batten tension slightly


n tension slightly Table of Contents


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