Another sail trim guide

October 3, 2007 at 1:44 pm | Posted in sail trim | Leave a comment

http://www.mssa.org/cms/pdf/pub/MSSAsailTrim.pdf

How to Maximize Lift

(and minimize drag)

• Lift and drag is variable

• Sails may be adjusted:

– Light Air

• Deep Draft, Draft Aft, more sail area

• Fuller shapes work because light air produces less

drag.

– Medium Air

• Reduce Draft, Draft Forward, maintain sail area

• Flatter shapes provide lift without excessive drag

– Heavy Air

• Reduce sail

– High wind velocities produce sufficient lift with much less

sail area.

– Overpowered is not fast

– Smaller flatter genoa/jib

Reefed mainsail, full out haul to flatten the mainsail

General Sailtrim/Boatspeed

Guidelines

• Light Air, Flat Seas

– Sail trim

• Full Shapes, deep draft

• Ease halyards, Outhaul and Cunningham

– Steering

• Foot off to keep the boat moving. Helm and Trimmers work

together to continually adjust sail and helm to the varying

conditions. As boat speed increases, point a little higher to

make distance toward the mark.

–Move crew to leeward

• Keep the boat heeled so it is ready to take advantage of any

breeze.

• Light Air, Choppy seas

– Arrgh! This is the worst!

– Foot off, keep boat moving, one wave can stop

you dead in your tracks, and take minutes to get

moving again. Don’t be greedy and try to point

too high.

• Move Crew to Leeward

– Try to sails from collapsing/flopping

• Medium Air, Flat Seas

– Yeah! This is by far the easiest to sail

– Start reducing draft in the sails (flattening)

• Outhaul

• Halyards (move draft forward)

• Cunningham

• Genoa Sheets and Car Position

• Medium Air, Choppy Seas

– With a continuous breeze, it is easy to get the

boat moving.

– Watch for the waves, if you hit one head on,

you will loose momentum. If you are about to

take a wave on the bow, steer down,

momentarily.

– Anticipation is key, don’t get caught sleeping

• Heavy Air, Flat Seas

– This is a transition state, most likely the wind

has just come up.

– You will need to reduce, flatten sail.

– Don’t be fooled. This state is short lived. The

waves will likely come soon. Use this time to

get ready.

• Heavy Air, Choppy Seas

– Reefed main, Tight Halyards, Cunningham

– Small, Flat Genoa

• 90% to 110% Genoa is in order

• Roller Reefing will reduce sail area, but don’t

expect to point very high.

– Watch out for big waves, they’ll stop you dead

in you tracks.

• Velocity Made Good (VMG)

– Strong Winds

• Sail more direct course toward mark, Run down

wind, boat speed will be maintained for Best VMG

– Light Winds

• Sail more of a broad reach to maintain boat speed

for best VMG.

Down Wind Sail Trim

• Loosen most sail Controls

– Ease Halyards

– Ease Outhauls

• Sails will be let out, air flow over sails will be

reduced, Sails will work in two modes:

– Drag Mode: Wind is pushing sails and boat down wind

– Lift Mode: Air flowing over sails produce lift when

sailing a broad reach

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