Sail trim and balance 2013 draftPresentation Transcript
Sail Trim and BalanceSail Trim and Balance with Kristen “kb” Berry
Sail Trim and Balance• The Big Question• One Language• Two Modes• Three Sources of Power• Controls• Balance• Putting it all together
What makes a boat go?
Let’s Develop aCommon Sail Language
One Language• Most sails have three edges• Most sails have three corners
One Language Head Leech LuffClew Foot Tack
One Language LUFF Draft ChordLeech Camber
What are theTwo Modes of Sailing?Two Modes of Sailing?•Fast and Slow?• Cruising and Racing?•Upwind and Downwind?
TWO MODES PUSH PULL
Push Mode• Sail blocks the WIND wind. Creating high pressure on windward side• More wind = more power H H LL• More area = more power
Pull Mode• Attached air WIND flows over both sides from leading to trailing edge• Outside air flows faster because of L H camber H L• Creates heel & forward force
Pull Mode - Keel Lift Keel Lift• Keel lift works the same way, below the water. L• Water flows over the curved surface of the keel. Leeway• Because of leeway, high H pressure builds on the LEEWARD side and keel lift occurs.
Pull Mode - The Watermelon Seed• When Sail Lift and Keel Combined Lift balance, the boat moves forward Keel Lift Force• Keels takes us upwind and sails take us downwind• We must have flow and Sail Lift balance
Pull mode is really FLOW mode.
So what mode are you sailing in?
WIND Close HauledNo GoZONE Beam Reach Broad Reach Run
What are thethree sources sail power? sail power?
Angle of AttackThe angle of a sail’s CHORD to the apparent wind.
WIND WIND WIND0 45 60Luffing Proper AoA Stalled
So what do telltalesshow us about AoA?
Attached Airflow Luff Luff
Attached Airflow Leech Leech
Let it out, until it luffs. Often doubt... Rarely in error. Rarely in error. Rarely in error. Rarely in error.
DraftThe AMOUNT of camber in asail and the LOCATION of the deepest point of camber.
Flat Deep Shape Shape Horizontal Profile:A deeper sail is more powerful but will also generate moredrag. A flat sail has less drag, but generates less power inlighter winds. Deeper sails for light air and flatter sails for heavier air.
Flat Mainsail Shape
Deep Mainsail Shape
Deep sails for light air.Flat sails for heavy air.Flat sails for heavy air.Flat sails for heavy air.
Twist The difference in Angle ofAttack from head to foot of a sail.The amount of leeward falloff of a sail’s leech.
UPWIND TWIST TWIST Note the top batten relative tothe boom. Both are showing the CHORD of the mainsail. Thetop batten is pointing to leeward while the boom is pointing behind the boat.
DOWNWIND TWISTTwisting OPEN the leech allows the wind to flow freely from leading edge to trailing edge. More twist equals more flow.
Main Controls Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard Sheet Traveler Vang Outhaul BackstayCunningham
Jib/Genoa Control Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard SheetLead Car Blocks Backstay
Main Controls Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard ✔ Sheet ✔ ✔ Traveler ✔ Vang ✔ ✔ Outhaul ✔ Backstay ✔ ✔Cunningham ✔
Jib/Genoa Control Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard ✔ Sheet ✔ ✔ ✔Lead Car Blocks ✔ ✔ ✔ Backstay ✔
BALANCE• How does sail trim affect affect balance?• How does heel affect balance?
Mainsail Center of Headsail Effort Center of Effort ☢ ✇☢CombinedCenter of Effort Center of ✇ Lateral Resistence
Boat Sails Boat Turns Straight To Port View from astern Boat is heeledBoat is level to starboard
☢ ☢ View from astern ✇ ✇ Boat is level Boat is heeledAnd TURNING and steering straight
What do we want?When do we want it?and how do we get it?
Light Air Days• GIVE ME POWER!• MORE FLOW!• MORE DRAFT!• MORE TWIST!
Light Air Days No Stall! Eased sheets, boom off AoA centerline. All telltales streaming aft. Not steering close hauled. Ease halyard, outhaul, backstay, Draft cunningham. Move jib lead forward. Open twist to promote flow at topTwist of sail. Jib and main should “match” Leeward heel to promote sail camber. Forward weight to reduceBalance drag. Trim crew weight to helm “feel.” Slight tug.
Moderate Air Days• No compromises• Max point and speed• Minimum Twist• Design Draft• Design Heel - Flatter is faster
Moderate Air Days Max trim, slight stall for point. Boom on centerline. Inside jib AoA telltale lifting, top leech telltale slight stall. Draft Moderate depth, starting to flatten Twist No twist for maximum power. Designed heel. Less than 10 Balance degrees. Trim crew weight to helm “feel.” Neutral tug.
Heavy Air• WHOA!!!!!!• Depower sails• Open AoA for waves• Keep the boat balanced
Heavy Air Days Traveler down for open AoA. AoA Jib/Genoa eased or even moved outboard Flat, Flat, Flat. Tight halyards and Draft OBC’sTwist Lots of twist to help depower. Reduce heel by moving crew weightBalance to windward. Balance CEs to keep helm pressure to light tug.
Angle/ Jib TelltaleGear When How Boom Heel Telltale Tales Straight line sailing in Main eased and twisted1st light air Boom below centerline. Light air with waves All flattening controls Press on the jib so that Whenever you need eased. Wide angle the windward telltale Jib lead forwardGear to accelerate Some leeward heel Inhauler on so mid-leech flows straight. After tacks/motorboat wakes pokes to leeward When sailing in bad air Max headstay sag Mainsheet trimmed so2nd Flat water in light air Chop in moderate air top batten is parallel to boom Leech telltales flows Moderate angle Inside telltale begins to bounceGear Nearly flat boat No luff in jib Footing mode 100% Boom on centerline Designed draft Mainsheet trimmed to3rd Moderate breeze max Flat water Top batten poked to Windward telltale lifts Point Mode windward Max point mode to 45 degreesGear Heavy air with flat Leech Telltale (on Flat boat Small luff bubble along water main) stalled 50% Jib luff Tight backstay Little headstay sag Tight leech, but active4th sheet ease to stay in Windward telltale lifts Overpowered control Feathering vertical most of the Moderate air with Top batten flowing Flat as possible time.Gear more waves than wind 100% Especially if you have Front of jib likely Survival Max flattening to bear off for waves luffing Vang hard Boom below center
More Helm Less helm Move crew forward and to Move crew aft and toCrew position leeward windward Rake the mast farther Mast rake Rake the mast farther aft forward Trim the leech harder and Ease the sheet and induceMainsheet trim reduce twist twistAngle of heel Heel more to leeward Flatten the boat Make sails fuller; especially Flatten sails; especially the Sail shape the main main Move it down and orCenterboard forward Move it up and or aft.
Thank you!• Let’s go sailing!• Submit your question cards.• Stay in touch - my pledge to you.• Resources.
SAIL FAST, SAIL SAFE AND STAY IN TOUCH KRISTEN BERRYKRISTEN@JWORLDANNAPOLIS.COMPHONE - 410-599-3542
Steering With Heel and Crew Weight
VANG ip tt as m on aft lls Pu Mast bends Main FlattensTension Main Leech More Vang Boom presses Tension into mast causing lower mast section bending