To use the backstay effectively, rig tune has to be set right. I try to set the rig so that in the lulls with my backstay off, the sails are fully powered. Thus, when the puffs hit, I can tension the backstay, keep the boat under control, and keep it at a constant heel.

What do backstays do?

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. It is an important sail trim control and has a direct effect on the shape of the mainsail and the headsail.

How do you use back stay?

On boats with rigs that bend, the backstay helps depower the mainsail. When you add backstay tension on this type of rig you are essentially compressing a straw. The mast bends forward at the middle pulling the luff away from the leech thereby flattening the sail.