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Sail Trim for Cruisers Bill Jarvis FHYC 6/5/2009
Objectives: Avoid flogging/fluttering (ie. Use leach lines) Protect cloth from UV Control Healing What is optimum? 15 deg? Avoid rudder deflection over 5 deg As wind increases, headstay sags and cloth effort moves aft Therefore draft increases and weatherhelm increases Counter with more headstay tension (perhaps all the time) Telltales Concentrate on the leeward telltales
Mainsail Trim
Light Wind (6 kts at mast, near 0 at water)
Due to the wind gradient, as you go aloft, apparent wind speed increases and apparent angle changes 1/ Allow boom to rise to allow twist 2/ Center boom with traveler 3/ Trim with mainsheet to get telltales flowing (top one is most important) 4/ Outhaul is relaxed
Moderate Wind Less wind shear (gradient) but more mixing and turbulence at surface Therefore, reduce (but not eliminate) twist 1/ Traveler dropped toward centerline 2/ More mainsheet to pull boom down 3/ Tighten the outhaul and halyard to move draft forward (should be at about 50% position) 4/ Top telltale should be streaming most of time with an occasional flicker to leeward 5/ Play traveler in puffs but bring it back to weather as boat accelerates Note: Boomvang controls boom when going downwind; sheet does it when going to weather.
More Wind 1/ Traveler drops to leeward 2/ Tighten outhaul, vang, halyard 3/ Tighten Cunningham 4/ Bend mast (backstay adjuster puts bow into mast, moving middle forward) Draft still should be at 50%, but much less pronounced 5/ Play sheet in puffs Tighten leech cord until fluttering stops. Should have a leech cleat at reef point. Don’t forget to loosen before shaking out reef.
Headsail
Upwind Want all telltales flowing – match twist of sail to the wind Ex. If top telltale breaks first, car needs to go forward In light air, bring cars aft, trim to upper telltales As wind builds, twist decreases, move car forward As wind increases more, need to de-power top of sail, therefore move car aft; Tighten halyard; increase headstay tension.
Furling gear NOT meant for reefing. No reinforcement at leech and foot. Will cause fabric to stretch. Furling gives less area but deeper shape therefore MORE power. Use the foot and leech cords only as needed to eliminate flutter.
Off the Wind Top of sail wants to twist – may actually be contributing nothing. Car needs to go forward and outboard – use snatch block on toerail or on stanchion base Should be able to sail nearly 150 deg apparent then go wing-on-wing at 150 deg.
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