Rig tuning - aft lowers?

[jarcher]

Hi All...

I read the threads here on rig tuning, but I have a question not covered therein.

My Scampi 30 MK-IV is a masthead rig with one set of spreaders. The mast is like a phone pole. The upper shrouds go up the the spreaders then up to the mast head, as normal. I then have two sets of lowers. One set attaches to the mast right at spreader height and lands at chain plates positioned even with the front of the mast.

A second set of lowers connects to the mast in the same spot, but lands a few feet aft of the forward lowers. I can't figure out what these are for or how to tune them. The boat had some weather helm, so I loosened the shrouds, released the tension on the back stay (its adjustable) and then tightened the forestay to bring the mast more upright. I then tightened the upper and forward lower shrouds to 20% breaking using a loos gauge. Next, when I tightened the aft lowers, it made the mast seem to bend forward at the spreaders.

I released the tension on the aft lower shrouds to about 5% or less, and that seemed to make the mast straight again. There is also a baby stay that comes down to a line and a purchase, and aft to the cockpit. This doubles as the spinnaker pole downhaul.

I have seen a picture of another Scampi that had a purchase on these aft lower shrouds, but mine have turnbuckles.

Of course I don't want the mast bending forward above the spreaders. It seems that these aft lowers would fight an attempt to bow the mast by tensioning the back stay.

Any ideas? Thanks...