rig tuning question
 

i recently installed a backstay adjuster on my fractional rigged hunter 35. the rig has aftswept spreaders with uppers, intermediates and lowers. the forestay is tensioned mostly by the upper shrouds. in order to maintain the proper pre-bend (2") that matches my mainsail the backstay is set quite loose (5%) with the uppers at 24% the intermediates at 16% and the lowers at 10%. when the backstay is tensioned to 20% of the breaking strength i get the desired bend (7"-8") to flatten the sail. when the backstay is tensioned the uppers are at 20% the intermediates are at 15% and the lowers are at 12%. i am concerned that the backstay is too slack when set for the pre-bend. any insight would be appreciated.
thanks.

Ahh, tuning
 

This be a tricky one, as a Hunter with a backstay is a little like Paris Hilton with a boyfriend; it makes for a useful addition, but it isn't exactly essential, and can complicate an already delicate situation.
With the mast at minimum bend, your backstay essentially dead slack, your uppers are extremely tight. This is understandable, as they are performing the backstay function. Then, when your backstay is extremely tight, and you have the mast shape you want, the uppers get down to a more reasonable 20%. I would try starting with the backstay a little tighter, and the uppers a little looser. This should also result in taking a little load off the intermediates, which are also on the tight side when the mast is straight.
I'd also look at how fair a curve you are getting, as the max bend isn't as effective for the sail — nor as kind to the mast — if the bend is localized or segmented.
Oh, and is this a continuous rig, or a B&R?
Fair leads,
Brion Toss