In a traditional hemp and sandbag rigging system
the clew is used to join the several ropes which support the batten
to a single control line. This control line is then tied to the belaying pin
on the pin rail
, or counterbalanced with sandbags
The reason the clew is necessary is because older theatres often used wooden battens. On a wide stage several ropes were needed to support this batten. Without the clew to join ropes each rope would have to be individually sandbagged. Moving a single batten would require as many riggers as there are ropes. With a clew, one single rope can control the series of ropes,thus allowing the lineset to be operated by just one person.
Part of the Stage Rigging metanode