Sail Trim
Perfect
Trim
Over
Sheeted
Under
Sheeted
Leeward
Telltale
Hobie University, NAHCA
Page 9
30 Mar 02
Sail trim first requires that you use the main/jib sheet and traveler controls to adjusting the shape and
position of the sails with respect to the wind. Secondly that you steer your boat so that the leading edge
of the sails smoothly cut the wind while the rest of the sail gently bends the wind.
The left diagram,
under sheeted,
shows a sail that is soft just behind the leading edge or slightly luffing.
This sail will generate very little power. To correct this situation, either bring in the trailing edge of the
sail by sheeting in, or turn the boat off the wind slightly to fill the sail.
The center diagram,
perfect trim,
shows a sail that is smoothly cutting the wind and bending it to generate
maximum power in the sail. Note that the tell-tails are smoothly flowing back on both sides of the of the
sail. The most important tell-tails are the leeward tell-tails, usually the ones on the other side of the sail
from the skipper. Keep these tell-tails flowing back at all times, the windward tell-tails may act up a lit-
tle and in higher winds they will fly back and up at about a 45° angle.
The right diagram,
over sheeted,
shows a sail which is trying to bend the air flow too much, the air flow
breaks away from the sail on the leeward side and the air becomes turbulent causing the leeward tell-tails
to dance forward and back. To correct this problem, either sheet out to reduce the bend of the sail, or turn
the boat more into the wind allowing the air to better flow along the leeward side of the sail.
