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. Backstay tension also affects mast bend,
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.
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), 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.


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

"Roger Long" wrote in message
...
Our boat came with a backstay adjuster of the kind that has a heavy tackle
hauling down sheaves on a split leg.

(You can see it on this page http://home.maine.rr.com/rlma/Boat2.htm)

I can't see what this is doing on a masthead rig except maybe to unload
the hull when not being sailed. With a 3/4" hull cruising boat, I'm not
too worried about letting the stern back down in the water after sailing.
The former owner had a lot of funny ideas and maybe this was just one of
his responses to a boat which is not a hot machine going to windward.

I'd like to clean up the after deck area and it looks like I could
dispense with this by changing out one turnbuckle part and tensioning
appropriately.

Can anyone give me a reason for keeping this set up on a cruising boat?

--

Roger Long