The headstay is the wire, rod or fibre stay that runs from the bow of the boat to the top or upper section of the mast, holding the mast up against the pull of the mainsail and backstay and providing the leading edge on which the headsail is set. In this glossary and in most of the sailing world it is the same thing as the forestay; some sailors, particularly on cutters and boats with an inner stay, reserve “headstay” for the outermost stay at the stemhead and “forestay” for the inner one. The experienced sailor knows that the headstay is the least controllable part of the rig and yet the one that most affects how the genoa sets, because its tension and sag decide the shape of the headsail’s luff.
Anatomy of the Headstay
At the bottom, the headstay attaches to the stemhead fitting or a chainplate at the bow through a turnbuckle and, critically, a toggle that lets the stay articulate as the sail loads it sideways. At the top, it attaches to a masthead fitting on a masthead rig or to a tang part way up the mast on a fractional rig. The stay itself is usually 1×19 stainless wire, rod on many racing boats, or a composite fibre such as PBO or Dyneema® on the most weight-conscious yachts.
The headstay’s length sets mast rake, the fore-and-aft lean of the mast, which in turn sets helm balance. A longer headstay rakes the mast aft, moves the sail plan’s centre of effort aft and increases weather helm; a shorter one does the reverse. Adjusting the turnbuckle by a few turns is one of the standard tuning steps when a boat has too much or too little helm.
Headstay Tension and Sail Shape
From the sailmaker’s point of view, the headstay is the genoa’s luff spar, and how straight it stays under load defines the sail’s entry and depth. No headstay is ever perfectly straight while sailing – wind pressure on the headsail pulls it to leeward and aft in a curve called headstay sag. Every genoa is cut with a luff curve that anticipates a certain amount of sag; when sag matches the design, the sail sets as drawn. More sag makes the sail fuller and its entry rounder, which is powerful in light air and chop but limits pointing. Less sag flattens the sail and fines up the entry for pointing in flat water and a breeze.
On a masthead rig, headstay tension comes almost entirely from the backstay, so the backstay adjuster is effectively the genoa depth control. On a fractional rig, the backstay bends the mast more than it tensions the headstay, and headstay tension comes from shroud tension, spreader angle and runners or checkstays if fitted. This is why the tuning guide for a fractional boat spends so much time on shroud tension: it is really setting up headstay sag for the jib.
Cruising and Racing Perspectives
The cruising sailor with a furling genoa has a headstay that is set once and lived with. The aim is enough tension to keep sag moderate in a fresh breeze without over-compressing the mast or overloading the chainplates, and a rig tuned so the furler rolls freely.
The racer adjusts headstay tension constantly. A hydraulic or cascade backstay on a masthead boat, runners on a fractional boat, and even a headstay adjuster at the stemhead on some classes let the crew change genoa shape through the wind range.
Related Terms
Headstay and forestay are interchangeable for most purposes; an inner forestay or staysail stay sets inboard of the headstay for a staysail or storm jib, and a babystay runs from low on the mast to the foredeck to control mast bend. The J measurement in rating rules is the horizontal distance from the forward face of the mast to the point where the headstay meets the deck or its extension, and I is the height of the headstay’s intersection with the mast above the sheerline – see also backstay, shroud and rake.
Frequently Asked Questions about the Headstay
Is the headstay the same as the forestay?
For most boats, yes. On cutters and boats with two stays forward, headstay usually refers to the outer stay at the stemhead and forestay to the inner one, but usage varies from club to club.
How tight should the headstay be?
Tight enough that sag stays moderate in a full-sail breeze, without the mast pumping or the boat’s structure showing strain. Riggers often quote a static tension in the region of 15 percent of the wire’s breaking load as a starting point, refined under sail by watching the genoa luff.
How often should a headstay be replaced?
Wire rigging is commonly replaced every ten to fifteen years, or sooner on boats sailed hard or kept in the tropics. A headstay hidden inside a furler deserves the same schedule even if it looks fine at deck level.
The headstay is the front edge of your engine upwind. Keep it sound, understand where its tension comes from on your rig, and learn to read its sag against your genoa’s shape – see the separate entry on headstay sag – and the headsail you paid good money for will do the job it was designed for.