i kinda thought depending on how the supports of the hinge and rope were handled to shock and relieve line that spars could pull together sharply, then recoil in the opposite direction (apart), depending on load handling.
Moving the close spar with load towards climber, as spar holding his lifeline pulled away. The angle of the lifeline pulling across hard for climber to fight. The lifeline is higher than the rig, so would get more movement. As the lifeline pulled him into close spar that was spreading apart towards him, with load and it's line.
If there wasn't slack in climbing line, could get yanked?
i'd kinda want load close spar signifigantly less by either having the support of the far spar much higher in relationship to the support of the close spar, or each spar to have a seperate rig. Then let the close spar rig run, as far spar catches(is held tight). The motion of load on catching spar/far spar would be across, therefore not so much impacting down. Then tie into less loaded, closer spar; that would have less movement, less line angle, and less span to sweep across in case things went wrong.
i redirect through a carabiner sometimes, as long as another support guarantees the line won't be sharply bent by the carabiner.
It just looked a lil'wierd to me i guess....
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