PAGE 24 • AUTUMN 2006 THE JOURNAL OF THE AMERICAN SAILING ASSOCIATION
INSTRUCTOR TIP
By Capt. Bill Brooker
Using the Outhaul to Enhance Mainsail Performance
T
he outhaul - it’s that little gizmo at the end of the
boom attached to the mainsail clew. It must be
important because I’ve never seen a sailboat
without one. Actually, next to the mainsheet, it’s the
most important gadget in main sail trim. The mechanics
of the outhaul are pretty simple. It simply moves the
clew back and forth a few inches. What that does to the
sail is incredibly important. According to Bernoulli’s
Principle if air has to travel over a shape, like a wing,
where the distance is farther on one side than the other,
the longer side will experience a drop in pressure or lift.
The lift increases as the curve increases.
The outhaul controls curve (draft) in the bottom of the
main sail. The lower part of the main is where the largest
sail area is located, thus controlling the draft here
(Top to bottom) Main with outhaul snug. Main with outhaul
controls most of the power of the main. It’s not called
eased. Wing in normal configuration. Wing with flaps extended.
the mainsail for nothing. It’s the main sail of the boat. The high lift shape of wings and sails does have a lot of
Easing the outhaul increases draft and tightening it drag. When sailing off the wind, releasing the outhaul
decreases it. If we compare the sail to the wing of an gives the sail a better shape to help “push” the boat along.
airplane, which is often done, easing the outhaul is like
applying the flaps, those long panels at the back of the
Most sailmakers like what’s called the “loose foot”
wing. Next time you fly, watch what happens to the wings
mainsail where the foot of the main is not inserted in the
before take off. That weird shaped wing now has a lot
bolt rope slot of the boom. This allows the main to take on
more lift. Now, how and when shall we increase or
a smoother shape. They can convert any main to loose
decrease sail draft?
foot by cutting off the bolt rope and replacing it with sail
tape. Also, the outhaul should be easy to use and
Generally, in light air or when the seas are lumpy, this is convenient to operate. A small block and tackle at the end
when you want the main to have the most lift. Racers call of the boom that’s cleated at the gooseneck or leads back
it “shifting gears.” Power up the main by easing the to the cockpit, makes sailing easier and more fun.
outhaul. When the seas flatten, decrease the draft by
tightening the outhaul. This shifts the sail into high gear Capt. Bill Brooker is the owner and operator of Sara Bay
just as the plane, soon after takeoff, will retract the flaps. Sailing School and Charter in Sarasota, Fla.
AMERICAN SAILING ASSOCIATION
P.O. BOX 12079, MARINA DEL REY, CA
PRESORTED
90295-3079 TEL: 310/822-7171
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