Backstay

A backstay is a piece of standing rigging on a sailing vessel that runs from the mast to either its transom or rear quarter, counteracting the forestay and jib.

In both of these cases the mainsail extends aft of a line from masthead to stern, and so a permanent backstay would interfere with the operation of the sail.

As a direct consequence of its attachment point (below the top of the mast) a running backstay is always adjustable because it must be manually engaged and disengaged during every tack or jibe.

The overall effect of tensioning the running backstay is a shallower mainsail (less camber) combined with a reduction in headsail sag.

[6] Since these insulators form part of the rigging, not only must they not leak current, but they must also be strong and durable enough not to fail mechanically under the sometimes tough load conditions experienced in sailing.