If I got it wrong, it's because Harken got it wrong. This was a quote from
their website.

--
"j" ganz @@
www.sailnow.com

"Terry Spragg" wrote in message
...
Capt. JG wrote:

From the Harken website... http://www.harken.com/blocks/bksty.php

On masthead rigs it is the primary control for headstay tension, which
affects genoa shape. Ease the backstay to add draft to the genoa for more
power in light-to-medium conditions; tension the backstay to remove draft
for better pointing in heavy air.

You got it all wrong. Adjustable back stay is a fancy turnbuckle on my
boat, with flip up adjuster handles, tension in the headstay can be
increased or decreased, though not enough to actually move the masthead
enough to grossly influence weather helm.

Genoa shape is governed by luff tension independant of headstay sag. A
stretchy genoa luff cannot accomplish as much improvement in windward
performance as a sail change, except in marginally increased wind
conditions, which exceeded, demand a smaller sail, sheeted inboard of the
usual genoa track and very flat.

It is so funny to watch genoa drivers struggle with heel and helm, when a
smaller properly set sail can so easily outperform them to windward,
especially since the right sail will last for years while a baggy genoa
may not have survived it's first race, shapewise.

One should not expect to actually stretch a forestay and the luff hanging
from it to any good effect.

While I must admit the adjustable backstay has some utility, presetting
the shrouds tighter aft and allowing the wind to do it's work is a far
superior sail shaping solution, cruisingwise, if you want to automatically
flatten the middle of the main in rising winds, not a bad idea in the
right circumstances. Overall main shape is governed by it's luff tension,
cunningham or gooseneck downhaul, along with, of course, it's clew
outhaul.

The backstay is not a sail control, but with enough adjustment, matched in
antiphase with the headstay adjustment, can give a modicum of weather helm
adjustment, though it would only suit a small adjustment for a given sail
combination in a small range of wind conditions.

Better a strong jib halyard hoist and a stretchy luff rope, not wire,
though a wire to rope splice in the halyard is nice to minimise warp under
wind.



Backstay tension also affects mast bend,

depending on lower shrouds, automatically

flattening the main and extending its range before a reef is required. It
also changes mast rake, especially off the wind where dumping the rig
forward reduces weather helm for reaching and running.

Can yours move the masthead even 3 inches? Better to reduce sail according
to weather helm dictats. A jib downhaul can allow a man to safely change a
jib in seconds, only hanking it on at the foredeck, possibly changing the
sheets, and halyard shackle, and leaving the doused genny siezed on deck,
hanked on below the pennant for the 75% working jib, depending on winds,
and it's self tending club boom, ready to instantly rise again in easing
winds. That is why hanks should be few and for taming the jib on deck
only. It's halyard should control it's shape by stretching the luff and
taking away some of the forestay load. Maximum stretch in a genny luff
should be at about half of the headstay tension. A wire luff genny is not
really adjustable, sail cloth can stretch a lot, and can be used and
abused.

Light air sails are fragile.

On fractional rigs, the primary affect of the backstay is to shape the
main through mast bend. Since the main is so important on a fractionally
rigged boat (comprising the majority of sail area)

Not in a lot of furler genny only boats I see go by

, the system has to be designed
for convenient adjustment. It should be adjusted frequently, so if you
can't tolerate having crew moving off the rail to tweak the backstay
every time, place it where the main trimmer is invited to make fine
adjustments to backstay tension. It should be as natural as dropping the
traveler or trimming the fine-tune.

The fine-tune what?

The traveller is the original hi-tech toy nobody really needs or uses
properly. A good boom vang can do what a traveller does and more, and it
doesn't get in the way.

Terry K