A stay is a piece of standing rigging that supports the mast in the fore-and-aft direction. The forestay or headstay runs from the bow to the upper part of the mast and stops it falling aft; the backstay runs from the stern to the masthead and stops it falling forward. Wires that hold the mast sideways are shrouds, not stays, though sailors often say “stays” loosely for all standing rigging. A beginner needs to know that stays keep the mast up; an experienced sailor knows that stay tension is the single biggest influence on headsail shape, because every centimetre of headstay sag adds fullness to the genoa exactly where you least want it.
Types of stay
- Forestay or headstay: from the stemhead to the masthead on a masthead rig, or to a point part way up on a fractional rig. It carries the luff of the jib or genoa, whether hanked, in a luff groove or wrapped around a furler foil.
- Backstay: from the transom or quarters to the masthead. On many boats it is adjustable, with a hydraulic ram, a cascade of blocks, or a wheel, so that tension can be varied under way.
- Inner forestay: set inboard of the headstay to carry a staysail or storm jib. On cutters it is permanent; on sloops it is often removable and clipped away when not in use.
- Running backstays or runners: adjustable stays led to the quarters that support the mast at the hounds on fractional rigs and are tensioned on the windward side only.
How stay tension shapes the sails
Pull on the backstay of a masthead rig and the headstay tightens. A tighter headstay sags less to leeward under the genoa’s load, which flattens the entry of the sail, moves the draft aft to where the designer put it, and lets the boat point higher. Ease the backstay and the headstay sags, the genoa gets fuller and more powerful, and the boat is faster but less close-winded. On a fractional rig the backstay also bends the mast, flattening the mainsail as it pulls the top aft. The relationship between backstay, headstay sag and sail depth is the reason a sailmaker asks how much backstay you carry in different conditions before designing a new genoa.
UK Sailmakers design headsails with a luff curve that anticipates a particular amount of headstay sag: a little for a stiff rig with a hydraulic backstay, more for a cruising boat with a fixed backstay and a furler. If the rig is set up very differently from what the sail expects, the sail will look either too flat or too full along the luff and no amount of sheet trimming will fix it. Matching stay tension to the sail is part of the tuning, not an afterthought.
Materials
Most stays are 1×19 stainless steel wire, which is stiff, strong and reliable, with swaged or mechanical terminals. Rod rigging, a single solid stainless rod, stretches less and lasts longer but needs specialist handling and must be inspected at the cold heads. Racing boats increasingly use fibre stays of PBO, carbon or Dyneema, which save weight aloft and stretch very little, though they need protection from ultraviolet light and chafe. A removable inner forestay is a natural candidate for Dyneema because it can be coiled and stowed.
Tuning tips
Set the rake first: with the boat upright and the backstay at a moderate setting, hang a weight from the main halyard and measure how far aft of the mast it hangs at the gooseneck. Rake affects helm balance, so add rake for more weather helm and reduce it if the boat is already heavy on the helm. Then set the headstay tension; a rig gauge reading of 15 to 20 per cent of the wire’s breaking strength is common on a masthead cruiser. Mark the backstay adjuster so you can reproduce settings, and ease it when the boat is moored.
Related terms and expressions
Headstay and forestay are the same wire on most boats; where a boat has both, the forestay is the inner one. Shrouds support the mast sideways. A staysail is a sail set on a stay other than the headstay. A boat is in stays when she is head to wind in the middle of a tack, and has missed stays when she fails to come through the wind and falls back onto the old tack. To be hove to is unrelated to stays but is often confused with being in stays by newcomers.
Frequently Asked Questions about Stay
What is the difference between a stay and a shroud?
Stays run fore and aft and support the mast against pitching loads; shrouds run athwartships and stop it falling sideways. Both are standing rigging.
How tight should my headstay be?
Tight enough that the sag under sail is what the headsail was designed for, typically 15 to 20 per cent of the wire’s breaking strength on a cruising masthead rig. If the luff of the genoa scallops between hanks or the entry looks very round, the stay is too loose.
Stays hold the rig up and, just as importantly, hold it at the shape the sails were cut for. Learn what your backstay does to the headstay, keep the wire and the terminals inspected, and your sails will set the way the loft intended.