Sail Trim and Balance Lecture from Singles On Sailboats Spring Training.

1. Fundamental
Sail Trim and Balance
with Kristen “kb” Berry

2. Sail Trim and Balance
• The Big Question
• One Language
• Two Modes
• Three Sources of Power
• Controls
• Balance
• Putting it all together

3. What makes a boat go?

4. Let’s Develop a
Common Sail Language

5. One Language
• Most sails have
three edges
• Most sails have
three corners

6. One Language

7. One Language
Luff

8. One Language
Leech
Luff

9. One Language
Leech
Luff
Foot

10. One Language
Head
Leech
Luff
Foot

11. One Language
Head
Leech
Luff
Foot Tack

12. One Language
Head
Leech
Luff
Clew Foot Tack

13. One Language
LUFF
Chord Draft
Camber
Leech

14. What are the
Two Modes of Sailing?
• Fast and Slow?
• Cruising and Racing?
• Upwind and Downwind?

15. TWO MODES
PUSH
PULL

16. Push Mode

17. Push Mode
• Sail acts as a WIND
block to the
wind.
• More wind =
more power
H H
• More area = LL
more power

19. Pull Mode

20. 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

21. 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.

22. Pull Mode - The
Watermelon Seed
• When Sail Lift and Keel Combined
Lift balance, the boat Force
moves forward Keel Lift
• Keels takes us upwind
and sails take us
downwind
• We must have flow and
Sail Lift
balance

24. Pull mode is really
FLOW mode.

25. So what mode are you
sailing in?

26. CLOSE HAULED

27. Beam Reaching

28. Broad Reaching

29. WIND
Close Hauled
No Go
ZONE
Beam
Reach
Broad
Reach
Run

30. What are the
three sources
sail power?

31. Angle of Attack
The angle of a sail’s CHORD
to the apparent wind.

32. WIND WIND WIND
0
45
60
Luffing Proper AoA Stalled

33. So what do telltales
show us about AoA?

34. Attached Airflow
Luff

35. Attached Airflow
Leech

36. When in doubt...
Let it out, until it luffs.
Often doubt...
Rarely in error.

37. Draft
The AMOUNT of camber in a
sail and the LOCATION of the
deepest point of camber.

38. Flat Deep
Shape Shape
Horizontal Profile:
A deeper sail is more powerful but will also generate more
drag. A flat sail has less drag, but generates less power in
lighter winds. Deeper sails for light air and flatter sails for
heavier air.

39. Flat Mainsail Shape

40. Deep Mainsail Shape

41. Deep sails for light air.
Flat sails for heavy air.

42. Twist
The difference in Angle of
Attack from head to foot of a
sail.
The amount of leeward falloff
of a sail’s leech.

43. UPWIND
TWIST
Note the top batten relative to
the boom. Both are showing the
CHORD of the mainsail. The
top batten is pointing to leeward
while the boom is pointing
behind the boat.

44. DOWNWIND
TWIST
Twisting OPEN the leech allows
the wind to flow freely from
leading edge to trailing edge.
More twist equals more flow.

45. TWIST
Wind Speed

46. Sail Controls
• Primary Mainsail
Controls
• Primary Jib/
Genoa Controls

47. 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 ✔

48. 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 ✔

49. BALANCE
• How does sail
trim affect affect
balance?
• How does heel
affect balance?

50. Mainsail
Center of
Headsail
Effort
Center of
Effort
☢
✇☢
Combined
Center of
Effort Center of
✇ Lateral
Resistence

51. Boat Sails Boat Turns
Straight To Port
View from
astern
Boat is heeled
Boat is level
to starboard

52. ☢ ☢
View from
astern
✇ ✇
Boat is level Boat is heeled
And TURNING and steering straight

54. What do we want?
When do we want it?
and how do we get it?

55. Light Air Days
• GIVE ME POWER!
• MORE FLOW!
• MORE DRAFT!
• MORE TWIST!

56. 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 top
Twist of sail. Jib and main should “match”
Leeward heel to promote sail
camber. Forward weight to reduce
Balance drag. Trim crew weight to helm
“feel.” Slight tug.

57. Moderate Air Days
• No compromises
• Max point and speed
• Minimum Twist
• Design Draft
• Design Heel - Flatter is
faster

58. 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.

59. Heavy Air
• WHOA!!!!!!
• Depower sails
• Open AoA for waves
• Keep the boat balanced

60. Heavy Air Days
Traveler down for open AoA. Jib/
AoA Genoa eased or even moved
outboard
Flat, Flat, Flat. Tight halyards and
Draft OBC’s
Twist Lots of twist to help depower.
Reduce heel by moving crew weight
Balance to windward. Balance CEs to keep
helm pressure to light tug.

61. Thank you!
• Let’s go sailing!
• Submit your question
cards.
• Stay in touch - my pledge
to you.
• Resources.

62. SAIL FAST, SAIL SAFE
AND STAY IN TOUCH
KRISTEN
BERRY
KRISTEN@JWORLDANNAPOLIS.COM
www.galeforcesailing.com
PHONE - 202-549-1032