islander 36 fleet san francisco bay

Islander 36 FleetIslander 36 Fleet San Francisco Bay San Francisco Bay

Sail Shaping for Performance Sailors Sail Trim Lecture

Presented by Michael Whitfield

April 14th, 2007

Sail Shaping for Sail Shaping for Performance SailorsPerformance Sailors

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsFirst ModuleFirst Module

Overview of Objectives Foundational Concepts Trim Fundamentals Sail Controls Upwind Headsail Shaping

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsSecond ModuleSecond Module

Mainsail ShapingRig ControlShifting Gears for Conditions

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsThird ModuleThird Module

Trim LoopsHelm/Sail FeedbackSpinnaker Shaping

GoalsGoals

You will be able to shape sails effectively in a wide range of conditions using all available tools.

You will recognize and manipulate sail shape with onboard tools; enhancing boat speed, maintaining comfort, and capturing more wins!

Photo & Graphics credits: Islander 36 Class Association website, Lat38, North Sails, Max Ranchi, Volvo Ocean Race, Quantum Sails, Jboats Int.,

C&C Yachts, Chris Ray, Sail Magazine, Harken, All the IAC Teams, UK Sails and Sailnet

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsFirst SessionFirst Session


Foundational ConceptsFoundational Concepts

The Basic Laws of PhysicsFlying the BoatSystems Thinking ApproachPower Generation and ManagementThe One Wing Concept3 Dimensional Sail Shaping

Basic Laws of PhysicsBasic Laws of PhysicsNewtonian versus Bernoullian PhysicsLiftDrag & Displaced Hull Speed = 1.41 x Sq

Root WLWing Shape - Chord Length and DepthAerodynamic-Attached FlowHorsepower to Weight Ratio

Flying the BoatFlying the Boat

Sailing – We are a Vertically Oriented Airplane Flying in Two Mediums

Two Wings One Wing in the Air One Wing in the Water

AerodynamicsHydrodynamics

Low Speed Lift – 767 with Flaps DownLow Speed Lift – 767 with Flaps Down

Boeing 747 with Winglets Boeing 747 with Winglets

High Speed Lift Mach 2+High Speed Lift Mach 2+ F22 Raptor F22 Raptor

Boeing 767 Sailing?Boeing 767 Sailing?

IAC Boats That Drive Like AirplanesIAC Boats That Drive Like Airplanes

IAC Boats Flying – You Bet!IAC Boats Flying – You Bet!

Lift DiagramLift Diagram

How Lift WorksHow Lift Works

Sailing Forces DiagramSailing Forces Diagram

Drag and Displacement Hull SpeedDrag and Displacement Hull Speed

Low Drag Hydrofoil TrimaranLow Drag Hydrofoil Trimaran

Wing Shape DiagramWing Shape Diagram

Sailing Wing ShapeSailing Wing Shape

Systems Thinking ApproachSystems Thinking Approach Power Generation and Management Power Generation and Management

How Much Power is Enough?How Much Heel is Enough?How Important is Helm Balance?How Important is Pointing?

Islander 36 Example 2 Boats Sail 1 Mile Upwind at the Same Speed 1 Boat Points 1 Degree Higher 150 Feet of Gain = 4+ Boat Lengths!!!

Power Generation and ManagementPower Generation and Management

Speed

Pointing

Power

Generation

Leeway

5 Things I Want to Know Prior to 5 Things I Want to Know Prior to Leaving the SlipLeaving the Slip

Wind/Current DirectionRight-hand or Left-hand PropellerDoes the Prop Wash Hook-up to the RudderVessel DisplacementUnderwater Profile

Islander 36 Hull ShapeIslander 36 Hull ShapeKeel & RudderKeel & Rudder

The One Wing ConceptThe One Wing Concept

Jib or Genoa Combined with the Mainsail Create One Wing Shape!

Starts at the Leading Edge – Jib LuffEnds at the Trailing Edge – Mainsail Leech!Two Sails Nest Together to Create One

Wing!Start at the Front of the Wing, Set-up and

then Move Aft to Finish the Job!

Sailing Forces Diagram – One WingSailing Forces Diagram – One Wing

Farr 40 Worlds One Wing ConceptFarr 40 Worlds One Wing Concept

IAC - Two Nested Sails Create One WingIAC - Two Nested Sails Create One Wing

3 Dimensional Sail Shaping 3 Dimensional Sail Shaping

X, Y & Z Axes Horizontally – Fore and Aft Depth – Beam to Beam Vertically Aids – Draft Stripes, Boom, Mast, Forestay and

Backstay Jib & Main Leeches

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsFirst SessionFirst Session


Trim FundamentalsTrim Fundamentals

DefinitionsAnatomy of a SailSail ChoiceInitial Set-upPointing Modes

Full and Bye Power Mode Point Mode

Definitions & AnatomyDefinitions & Anatomy

Those Darn CornersThose Darn SidesAll the RestOverlap/Headsail SizeMaterials

Headsail PartsHeadsail Parts

Head Tack Clew Luff Foot Leech Leech & Foot Lines Cunningham Cringle

Typical Jib FeaturesTypical Jib Features

Angle of Attack & DraftAngle of Attack & Draft

Angle of Attack— The angle of the sail and boom to the apparent wind flow. In essence, angle of attack is controlled by the mainsheet and the boat’s heading.

Draft (Depth) Amount—This is the depth of the sail and the position of the greatest depth. This measure is technically known as Sail depth and is Depth divided by Chord Length. Thus, a one foot draft (Depth) in a ten foot long sail would have a 10% Sail Depth. In general fuller shapes will generate more power and flatter shapes less.

Draft PlacementDraft Placement

This critical measure is viewed fore and aft along seams and draft stripes (dedicated stripes normally found midway up the sail) and conveys information, in percentage terms, about the draft’s placement aft of the luff. Typically you will want to place your point of maximum draft in headsails about 40 - 45% of the way aft of the luff. Normally, it is enough to simply get the “draft forward of middle” and that is the phrase you will hear aboard performance boats.

Head Stay/Luff SagHead Stay/Luff Sag

Sails and the stays are supported only at the top and bottom. As a result, the head stay and luff sag considerably to leeward in moderate and heavy winds.

TwistTwist

This is varying angle of attack that the top, middle and bottom portions of a sail require to accommodate decreased wind strength near the surface relative to higher in the rig. Twist in headsails is a function of the fairlead position and the degree of sheet tension. Given a properly set up lead position, the sail’s telltales will lift (break as sailors refer to it) evenly along the entire luff of the sail.

Twist is used as a powering-up or de-powering action.

Wind ShearWind Shear

The wind at the top of the mast has a greater velocity and is traveling in a different direction than the wind at the deck level.

Remember That This is Only Noticeable on Boats with More Than 40ft. Rigs!

Overlap – Headsail SizesOverlap – Headsail SizesThe Sail’s Size - Many Bay Area sailor’s have only rarely, if at all, used the large overlapping sails called genoas. Alternatively, you may hear these large sails being discussed as a number one, or even as light and heavy number ones. The most obvious characteristics of a Genoa are its size and shape. Sailors measure genoas by the length of their LP, or luff perpendicular. To construct an LP, draw a line from the sail's clew to its luff, intersecting the luff at a right angle. The length of the LP divided by J (the distance from the forestay to the front of the mast) equals the overlap of the sail. LP divided by J = Overlap (%) On older boats, the largest headsails usually have a 150% overlap; No. 2s have a 130% overlap; No. 3s have a 98% overlap, and so on.

Sail MaterialsSail Materials

Jibs/Genoas/Mains Dacron & Stabilized Dacron Mylar Kevlar Aramid

Spinnakers Nylon Dynac Mylar

Sail ChoiceSail Choice

Example: I36 Headsails for Specific Wind Ranges

Light & Heavy #1 Genoa (150%): 1 - 15 Knots Apparent

#2 Genoa (135%): 16 - 25 Knots Apparent#3 Genoa (100%): 25 Knots + ApparentMore Than That – Let’s Go Home!

Initial Set-UpInitial Set-Up• Pick and set the proper sized headsail.Pick and set the proper sized headsail.

• Adjust draft position with halyard tension. Be careful if Adjust draft position with halyard tension. Be careful if you are using a sail built of low stretch fibers, you are using a sail built of low stretch fibers, Kevlar/Mylar sails are easily destroyed by overzealous Kevlar/Mylar sails are easily destroyed by overzealous hoisting.hoisting.

• Adjust the fairlead to provide wind appropriate range of Adjust the fairlead to provide wind appropriate range of draft & twist adjustment.draft & twist adjustment.

• Adjust sheet tension to get proper draft amount and twist. Adjust sheet tension to get proper draft amount and twist.

• Continuously adjust angle of attack and other parameters Continuously adjust angle of attack and other parameters as needed.as needed.

J24 Italian Nationals – J24 Italian Nationals – Check Set-up with Your TelltalesCheck Set-up with Your Telltales

Sail ControlsSail ControlsTools for Shaping Jibs/GenoasTools for Shaping Jibs/Genoas

HalyardSheetJib Fairlead Position – Fore and AftBarber Hauler – Inboard and OutboardCunninghamLeech and Foot LinesBackstay Adjuster

IAC One World – Genoa TrimIAC One World – Genoa Trim

Upwind Headsail ShapingUpwind Headsail Shaping

Sail Controls – How We Use ThemSail Trim Feedback and Boat FeedbackWhen, How and Why to Change Trim

Wind Speed Chop/Waves Point Mode or Power Mode Needed

Twist Impact

Trim Model - DiagramsTrim Model - Diagrams

Trim Modes – Full & Bye, Power and PointTrim Modes – Full & Bye, Power and PointFull & Bye Mode - Light AirsFull & Bye Mode - Light Airs

Sail Trim and Boat FeedbackSail Trim and Boat Feedback

WrinklesLuff Scallops Between HanksDistance the Leech was, and now is, from

SpreaderHeelHelm Balance or Lack There Of

Jib Luff WrinklesJib Luff Wrinkles

Luff Tension – Light ScallopsLuff Tension – Light Scallops

Islander 36 Jib Trim in BreezeIslander 36 Jib Trim in Breeze

J24 2002 NAs – ScallopsJ24 2002 NAs – Scallops

Islander 36 – Genoa TrimIslander 36 – Genoa Trim

IAC Genoa DesignsIAC Genoa Designs

5 Key Factors for Success5 Key Factors for Success

1. Think of the Jib and Main as One Wing!2. Set-up the Front of the Wing First, Jib Luff

Tension/Draft Position and Sheet Trim3. Finish with the Back of the Wing, Main Draft

Position and Leech Tension4. Set-up Luff Tensions with Small Wrinkles, then

Adjust to Conditions5. Use Telltales Vertically Sync’d to Confirm the

Position the Lead

Sail Shaping for Performance SailorsSail Shaping for Performance SailorsFirst Module – Q&AFirst Module – Q&A


islander 36 fleet san francisco bay

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