|
|
http://www.sejl.dk
Sail trim
SAIL TRIM
These are the sail trim guidelines
which work well on Diva boats
SPINNAKER:
- BROAD REACHING/DOWNWIND: Do NOT overtrim.
"When In Doubt, Let It Out." The spinnaker sheet trimmer is
constantly busy. The spinnaker should be just shy of the edge of collapse.
You should rescue it from a curl frequently. If the spinnaker is
touching the headstay it is DEFINITELY overtrimmed. If easing the sheet
causes collapse, then check pole height (Are the clews the same height?)
and pole position (Is the center seam parallel to the mast?)
- POLE POSITION while BROAD
REACHING/DOWNWIND: Pole should be square (90 degrees) to the wind. Check the
masthead fly. Keep the center seam parallel to the mast - if the seam
slopes to leeward aloft ease the pole forward (& vice versa).
- POLE HEIGHT while BROAD REACHING/DOWNWIND:
The luff should curl first just above the cross-cut panels. If the pole is
too LOW, the TOP WILL BREAK early; if the pole is too HIGH, the BOTTOM
WILL BREAK early. The pole is higher in heavy air & lower in lighter
air. In very light air when it can barely lift and fill, lower the pole
radically. A bottom break is deadly because it will collapse the whole
spinnaker.
- TRIM while TIGHT REACHING: You are flying
the spinnaker like a genoa.
- POLE POSITION while TIGHT REACHING: 1-2
feet back from the headstay
- POLE HEIGHT while TIGHT REACHING: If you
are having trouble carrying the spinnaker, the pole should be low with
very tight downhaul. Windward clew (at pole) may be lower than leeward
clew. Another school of thought is to try the pole high.
GENOA:
- RUNNING BACKSTAY TENSION affects fairlead
position dramatically. In heavy air & flat water the headstay should
be tight for maximum pointing ability. In light air or chop, the headstay
should be loose for maximum power. Set the fairleads after you have
decided upon windward running backstay tension. Off the wind, the runners
should not be very tight.
- FAIRLEAD POSITION: The genoa telltails
should break evenly along the luff. If the TOP LUFFS before the bottom,
move the LEAD FORWARD (increasing leach tension & reducing twist). If
the BOTTOM LUFFS before the top, move the LEAD AFT (relaxing tension on
the leech, allowing the clew to rise & the sail to twist). In light
air the fairleads move forward; in heavy air the fairleads move aft. If
the top of the genoa is tight into the top spreader while it is flying
away from the lower spreader, move the lead aft to open up the top of the
sail, making it possible to trim the genoa closer to the rig.
- TRIM: If the WINDWARD TELLTAILS break,
TRIM the genoa in or have the helmsman fall off. If the LEEWARD TELLTAILS
break, EASE the genoa out or have the helmsman come up. It is deadly slow
to sail with the genoa overtrimed (i.e., leeward telltails breaking).
- OFF THE WIND (REACHING): Barber-haul by
putting a block on the rail at the spot just underneath where the sheet
intersects the rail. This will prevent the leach from twisting off. Do NOT
overtrim. If the telltales are not drawing try easing the sheet(s) until
the leeward telltales start to flutter (meaning that the genoa was
overtrimmed); continue easing until the leeward telltales are streaming.
MAINSAIL:
- Mainsail trim is critical. It affects the
helmsman's ability to maneuver the boat. Going to windward (and while
maneuvering) in heavy air, a good mainsail trimmer is effectively steering
the boat with the helmsman. Under these conditions, an inattentive
mainsail trimmer will destroy the performance of the boat along with the
helmsman's ability to steer it. Keep at least the top leech telltail
streaming.
- WINDWARD (general principles): Top batten
parallel to the boom. For maximum pointing in flat water, introduce a
slight hook (reduced twist); to increase power in chop, let it fall off
slightly (more twist). Maximize power, weather helm, and angle of heel by
bringing the boom to centerline (but no higher). When the boat is
overpowered (the helmsman has too much helm and/or the boat heels more
than 30-35 degrees), ease the boom to leeward.
- MAST BEND: Tighten the backstay to bend
the mast and depower the mainsail. The luff will become looser (tighten
the cunningham). It will also be necessary to
tighten the mainsheet. A diagonal wrinkle running from the top/middle of
the mast down towards the mainsail clew means that the mast is overbent.
The checkstay can be tightened to take the bend out of the middle of the
mast and remove the wrinkle.
- LIGHT/MODERATE air going to WINDWARD: Use
the mainsheet to set the top batten parallel to the boom. Use the
traveller to place the boom on centerline and (if the helmsman asks) ease
the boom to leeward during puffs. The helmsman will probably prefer to use
the puffs to take bites to windward without the traveller being eased. The
eyelet shelf (outhaul) will be used to control the mainsail depth. The
luff tension (cunningham) should be moderate.
- HEAVY air going to WINDWARD (defined as
the traveller is now totally eased most of the time - what next?):
"Vang Sheeting" Use the vang to set the top batten parallel to
the boom. Use the mainsheet to control power, weather helm, and heel. The
helmsman will probably want the boom eased to leeward during puffs and
pulled back up to windward after the puff is over (communication is
vital). In extreme conditions, someone should be ready to ease (or dump)
the vang if the boat starts to go out of control. The eyelet shelf
(outhaul) will probably be maximally tight as will the luff tension (cunningham). Beware of letting the main flog - if
the mast pumps we could loose the mast (more disruptive than heeling too
much). Try to save the mast from pumping by keeping the leech edge of the
battens just drawing.
- OFF THE WIND: Use the vang to set the top
batten parallel to the boom. Use the mainsheet to ease
the sail appropriately as the boat falls off and bring it in as the
boat comes up. Keep at least the top leech telltail streaming.. The eyelet shelf will be eased unless it is really
heavy air. Aggressive trimming is especially important under starting
conditions (before the start, the main will be set up for windward work).
- GYBING: In heavy air (especially), it is
mandatory that the boom be sheeted in prior to being thrown over. Unlike
smaller boats and boats with telephone pole masts, our boat could lose her
mast if the boom comes over too hard.
Crew Weight:
XS has a narrow beam. We need to sail with a greater angle of heel than
the boats with a wider beam. The narrow beam also seemed to make her less
sensitive to side-to-side trim. We used to think that our crew did not have to
scramble to the rail to keep her level. Then we found out that the narrow beam
meant that XS is very sensitive to fore-and-aft trim and a cockpit full of crew
was hurting us. We need to keep crew
weight amidships and positioned inboard or outboard to maintain
the required angle
of heel (usually 15-25 degrees, depending upon the
windstrength.)
(thx to Mark & Co, sailing D39 XS, for the
sail trim tips)
|
RobShip |