Sail Trim for Cruisers Presented by

Introduction Many sailors most cruising sailors are self taught and have limited knowledge of the fine points of sail trim Knowing how to optimize your boat can: Make you safer Shorten your transit times Add to your enjoyment

Sail Trim for Cruisers Agenda The Basics Shaping the sail Draft Twist Trimming for different wind speeds Related topics Boat balance Reefing and it’s impact on sail shape

The Basics Wing Mode Kite Mode

The Basics Two “modes” If wind is forward of the beam…..the sails act as like a wing

The Basics Two “modes” 2. If wind is aft …..the sails act as like a kite

The Basics Up Wind In this mode a low pressure area is created on the back of the sail and the boat is “pulled up wind” The forward portion (first foot or two) of the sail (luff) should be pointed into the wind… or parallel to the Windex arrow You want to achieve equal flow over both sides of the sail…make both telltales fly!

The Basics Up Wind…”How to” If back telltale is stalled point the boat further up wind or ease the sheet If inside telltale is stalled point the boat down wind or trim the sail in toward the center of the boat

The Basics Telltales On the head sail in three places about 18” back from the luff Typically only on the leach of the main due to turbulence from headsail

The Basics Down wind Position the sails at roughly 90 degrees to the wind Sometimes increasing draft can add more power In this mode the boat is literally pushed by the wind and of course can not go any faster that the wind speed.

Basics The sails react to apparent wind As wind true wind speed increases (or boat speed decreases) apparent wind moves aft As boat speed increases (or true wind decreases) apparent wind moves forward

Shaping the Sail Draft Effects power and pointing ability Moving the draft forward improves pointing Deeper draft for more power in light conditions Flatten sail to depower in heavy conditions

Shaping the Sail Draft …how to… To create more draft easy the outhaul To move draft forward add halyard tension To further flatten the sail add backstay tension

Shaping the Sail Backstay tension Increasing backstay tension causes the middle of the mast to more forward…effectively flattening the sail

Shaping the Sail Twist Why does the sail need twist? Wind aloft can be higher than ground wind due to friction with the surface of the water The difference is commonly known as “Shear” Apparent wind angle is dependent on true wind speed Since the wind speed is higher at the top of the sail the wind angle is also higher (moves back)

Shaping the Sail Twist Boat Speed Top of the sail True Wind Speed Bottom of the sail True Wind Speed

Shaping the Sail Twist ….“How to” reduce twist Increasing tension on the leach of a sail decreases twist (“closes the top of the sail”) For the head sail…move the genoa car forward For the main…add Vang tension or put the traveler directly under the boom (“traveler down”)

Shaping the Sail Twist ….“How to” increase twist Decreasing tension on the leach of a sail causes increased twist (“opens” the top of the sail) For the head sail…move the genoa car aft For the main…remove Vang tension and/or put the traveler to windward to allow the boom to lift

Shaping the Sail To twist or.. not to twist… To power up the sail… adjust twist to make the all telltales fly To depower sail… twist the sail to stall the top portion

Boat Balance A properly balanced boat is fast and easy to handle A improperly balance boat is slow and can be dangerous

Boat Balance Too much mainsail and/or too little headsail will cause weather helm If weather helm is excessive the boat will be slow (drag caused by the rudder) and difficult to steer If the boat is grossly out of balance the rudder will not be able to correct and the boat may roundup Weather Helm Drag

Boat Balance Too little mainsail and too much headsail will cause excessive lee helm The boat will be slow (drag caused by the rudder) and difficult to steer If the boat is grossly out of balance the rudder will not be able to correct and the boat may experience an uncontrolled Jibe Lee Helm Drag

Boat Balance Most modern boats are designed with a small amount of weather helm This gives a better “feel” to the rudder and provides a margin of safety if the helm is left unattended (boat will go up into the wind and stall)

Reefing The first time you think about reefing do it!! Reefing usually changes the balance of the boat so it is important to check the balance by letting go of the helm and see what the boat does On older boats with big overlapping genoas it is best to reef the head sail first On newer boats with fractional rigs, reef in the main first

Reefing Remember that reefing usually changes the shape of a sail Reefing a large genoa can dramatically reduce your ability to get the boat up wind Modern rigs (fractional with loose footed mains) are better at maintaining sail shape when reefed.