Sail technology and trim - The Cleveland Sailing Association

Report
Nick Turney
North Sails


Sail Maker for 10 years
Professional Sailor
TP 52
 Farr 40
 RP 65
 Cookson 50


Professional Coach



Farr 40
TP 52
One Design
Rig Profile
Using
measurements
from your
boat
We use the rig profile
to design sails that
best fit the rig
Edge Curves
Horizontal and
vertical
curvatures
Broadseaming
Puts a yarn or
panel layout on a
design surface
Pressure
map for the
sail plan
Applies
pressure from
Flow to rig and
sails. Coupled
with specified
material
properties and
sail control
settings, sails
and rig are
deformed to
match sailing
conditions for
the specified
wind speed
RIG TUNE

Vertical shrouds (Uppers/
Cap)





Side to side bend
Flatness of main sail
Back Stay

Headstay sag, mainsail shape
Runners/ Checkstays


Headstay sag, mainsail shape
Big Lines

Rake, headstay sag, prebend
Diagonal shrouds (lowers)

SAIL CONTROLS

Sheets
Small Lines



Outhaul
Cunningham
Vang
1. With your boat on land and
your mast up, plumb bob the
keel to make sure it is straight
up and down
2. Set mast parallel to keel
3. Note that sheerline and
chainplates are often
inconsistent.
The fore and aft relation of
center of effort to center of
resistance creates helm,
weather or lee
More rake increases
weather helm, less rake
decreases it.
Static amount of bend in mast.
Affected by:
•Shroud tension
•Upper
•Lower
•Spreader angle
•Mast butt placement
•Placement at deck
Increased Tension on uppers,
gives
•Increased compression on
mast---more prebend
•Increased forestay tension, to a
limit.
Basic Rule
Oversheeting the mainsheet will
close the leech, increasing
weather helm and making the
bow want to point up
Easing the mainsheet opens the
leech and decrease weather
helm, making the boat easier to
sail straight
• The traveler
changes power in
the mainsail by
changing the
angle to the wind
• The traveler will
also affect
pointing ability
Boom on center line
Adjust to keep helm
Neutral
Up in light air
Down in heavy air
Draft forward is a better
heavy air shape, keeping
the leech more open to
depower
Draft aft is a better light air
shape, firming the leech for
power
Zero
+ 25 mm
+ 50 mm
+ 100 mm
Loose outhaul makes
the lower main fuller
for more power

Tighter outhaul flattens
lower main and opens
leech

Tight outhaul
20 mm looser
40 mm looser
60 mm looser
80 mm looser
• Light Air
–
–
–
–
–
Outhaul Loose
Cunningham off
Vang Loose
Backstay, loose
Traveler up to boom
on C/L.
– Mainsheet- Top
Batten
parallel
• Moderate
–
–
–
–
Outhaul Max
Cunningham loose
Vang Snug, no slack
Backstay, adjust
power to keep boat
flat
– Traveler, keep boat
flat
– Mainsheet top
parallel or slightly
open
• Heavy Air
– Outhaul Max
– Cunningham, no
wrinkles
– Vang very firm
– Backstay on hard
– Traveler, down, below
C/L
– Mainsheet, top batten
open 5- 10 degrees
• Jib Lead
– Controls Twist
– Forward=more power, less
twist
– Back= less power, more twist
• Jib Halyard
– Entry Position
– Full Entry is better for chop
– Fine Entry is better for flat
water
• Jib Sheet
– Controls Over all shape and
depth
– Inboard and Outboard
position
Light Air
– Medium halyard- finer entry, looser in chop
– Lead Forward
– Eased Sheet
Medium Air
– Tighter Halyard in flat water, looser in chop
– Lead Middle
– Tighter Sheet
Heavy Air
– Really Tight Halyard all the time
– Lead Aft
– Sheet eased
• A full shape is more
stable and good for
power in chop or when
pumping
• A flatter shape provides
more exposed area and is
most effective in flat
water
• Pole too high flattens the
luff and moves the draft
aft, closing the leech
• 2. Lowering the pole moves
the draft forward and
opens the leech
• Pole Height, Inboard and
Outboard
• Sheet Tension Discussion
• Pole angle
• Keep sheet moving
• Too little vang allows too
much twist and flattens the
top of the main,
depowering the sail
• Vang on decreases twist
and makes the top of the
main deeper and more
powerful

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