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Below we have illustrated and cataloged the suggested luff tension for light,
medium and heavy air.
Your main is equipped with a "Cunningham" grommet. This is placed nine to
eighteen inches above the tack.
Suggested Luff Tension:
Wind
Tension:
0 - 10
Medium (Until wrinkles behind luff tape disappear)
Draft Placement: 40 - 45% aft.
10 - 15
Firm (Cunningham 1/3 down)
Maintain Draft: 40 - 45% aft.
15 - 20
Maximum (Cunningham one-half to full down)
Maintain Draft: 40 -45% aft.
Foot or boom outhaul tension are adjusted to correspond to those of the luff,
the harder the wind blows, the more tension should be applied. Try as closely
as possible to match the foot tension to that of the luff. The actual mainsail
hoisting procedure is as follows:
1. Hoist the main to the full up position on the mast.
2. Now set the luff tension, as described above to the wind velocity.
3. Tension the boom foot outhaul to match that of the luff.
IMPORTANT: Never tension the foot of the main sail before tensioning
the luff. After sailing RELEASE the outhaul, give your sail a chance to
relax. Remember, the luff is no longer under tension. Leaving the foot
under tension causes unequal distortion.
F. TRIMMING THE MAINSAIL
Although much of all sail trim is done by "feel" rather than absolute, hard and
fast rules, we have a few suggestions that we hope will get you started in the
direction.
Trimming of the main is done with four basic controls:
1. Main Sheet
2. Main Boom Traveler
3. Boom Yang
4. Cunningham
Your boat mayor may not have as standard a main boom traveler or boom vang. We
suggest that you consider these options. Now on to trimming the main.
The most critical trim of your main occurs when going to windward. The place to
look for proper trim is the leech (batten) area of your main. Overtrimming will
show up in the leech area hooking to windward, i.e., causing excess drag and
heeling moment because the air is trapped at the back of the sail causing the
boat to heel. A loose or pumping leech indicates, conversely, that more trim is
needed. The function described above is primarily that of the MAIN SHEET.