S/V Constance, Alberg 30 #262 -- Sail Trim

Carol Hasse -- How to Trim Sails

-- based upon Stuart Walker's book _A_Manual_of_Sail_Trim_

-- Go Gear (Accleration) -- Slow acceleration after tacks, waves, or gusts and at the start.

Twist -- so that despite pitching, rolling, yawing, and distrubed air, some portion of the sail will retain attached air flow.
- Ease mainsheet and jibsheet -- all telltales flowing.
- Sag jibstay be easing backstay.
- Jib lead forward to increase fullness and close leech despite twist.
- Main traveler inboard to facilitate twist.
- Top batten in main twisted off compared to boom -- Greg Fisher
Draft -- so that increased twist will not reduce aerodynamic force.
- Ease outhaul for fullness in lower sections.
Jib draft forward -- facilitate attached air flow annd reduce side force.
Main draft aft.
Flexibility -- adapts to abrupt changes in wind strength and heading.
- Tension vang -- sag jibstay and float boom end.
Foot Off -- so that aerodynamic force is more aligned with heading.

Reduce twist by gradually tensioning main and jibsheet.
Slide jib draft aft by reducing jibstay sag by tensioning backstay.
Move jib lead aft to reduce twist.
In smooth water, increase sheeting angle as twist decreases; increase outhaul, reduce vang.

-- based upon Dave Dellenbaugh's "Rule the Run" Boatspeed Password: 6v6+xgA% (See Racing Webinars)

ease backstay.
ease the main till back-winded, then trim in a bit.
ease cummingham (a little bit of horizontal luff wrinkle).
boom perpendicular to apparent wind. (check windex.)
top batten parallel to boom and perpendicular to apparent wind. (check windex.)
top batten position is determined by the vang.
tighten outhaul to increase projected sail area. (fullness not needed.)
in light wind or sailing by the lee, twist top batten further forward.
in more wind, reduce twist at top batten. (more vang, be ready to release the vang.)
typically less vang downwind that upwind.

GPS Speed	Wind Angle	Wind Speed	Notes
5.6 - 6.0	60 apparent	12	traveller 1/3 down from midpoint, top telltale on main folded back behind, the rest streaming, 20* heel
6.0 - 6.4	80 apparent	12	traveller 1/3 down from midpoint, top telltale on main folded back behind, the rest streaming, 20* heel

A jib increases the total lift generated by a sail plan and makes that sail plan more efficient at typical sailing speeds. Cat rigged boats more efficient at higher speeds onn all points of sail and more efficient to windward (only?) if the total sail area is small (Lasers 76sqft, Finns 108sqft) p13
... lift and resultant driving force from a jib are approximately twice as great as from a mailsail of similar area .... p13
The net reduction in drag (due to the jib/main combination) ..., causes the aerodynamic force to act more forward, and therefore particularly benefits pointing. p13
... the jib, whose design, condition, and trim are the most important determinants of speed; .... p13
... an efficiency determining unit aft, the mainsail leech, whose design, condition, and trim are almost as important as determinants of pointing, leeway, and balance. p14
Never hold a sheet in the hand without an intervening winch or ratchet block, lest the force of the wind be dissipated in the movement of one's arm. p14