Backstay

Standing rigging leading aft from a mast to support it against forward loads.

A permanent backstay commonly leads from or near the masthead to the stern area. On some rigs its tension can be adjusted to control forestay tension and mast bend, affecting headsail shape and mainsail trim.

Not every sailing rig has a fixed backstay. Swept spreaders, runners or checkstays may provide some or all of the aft support, and running backstays must be handled in sequence during manoeuvres to avoid loss of support or contact with sails.