The head of a sail is its top corner – the point where the halyard attaches and from which the luff and leech run down to the tack and clew. On a triangular mainsail or headsail it is a single corner, usually reinforced with a headboard or a heavy webbing ring; on a square-top mainsail it is a short edge with its own batten and a pair of attachments. The word has other meanings aboard that you will hear daily:
- The head of a sail: the top corner, opposite the foot.
- The head: the toilet compartment, from the days when sailors relieved themselves at the head of the ship, forward by the beakhead.
- The head of the boat: the bow, as in “head to wind”, “headway” and a boat trimmed “down by the head”.
Beginners need to know that the halyard shackle goes on the head. Experienced sailors know that the head is the most heavily loaded few square centimetres in the whole sail, and that how it is built decides whether the top of the sail holds its shape or hooks and flutters as the breeze builds.
Anatomy of the Head
On a mainsail the head is normally finished with a headboard – a flat plate of aluminium or composite sewn or riveted into the corner, with an eye for the halyard shackle and often a slot or shackle for the top slide or headboard car. Headboards spread the halyard load across a wide patch of cloth and give the top of the sail a defined edge. Headsails usually have a pressed ring or a webbing loop instead, since they do not need the extra area a headboard provides and the ring is kinder to a furling foil.
Behind the fitting lies the head patch: several layers of reinforcing cloth cut so that their strong axis lines up with the loads radiating from the corner. In a cross-cut Dacron sail the patch is layered woven cloth; in a radial or load-path sail the tapes or radial panels themselves converge on the head. In UK Sailmakers’ Tape-Drive® and X-Drive® construction the high-modulus tapes run from the head down along the computed load lines to the clew and tack, so the corner is not a patch stuck onto the sail but the point where the sail’s skeleton meets.
Why the Head Matters for Shape
The top of a sail is where twist is controlled and where the apparent wind is strongest and freest, because wind speed increases with height above the water. Loads at the head are therefore high relative to the cloth weight up there, and a head that stretches or distorts lets the top of the sail fall off to leeward or hook to windward. Halyard tension acts through the head: if the headboard is skewed or the patch poorly aligned, tensioning the luff will produce diagonal wrinkles from the head rather than a clean, even luff.
Square-Top and Fathead Mainsails
Modern performance mainsails often carry a square top: instead of a point, the head becomes a short horizontal edge supported by a full-length top batten. The extra area up high is very efficient because it sits in stronger wind, and the top of the sail twists open in a gust and automatically depowers. The head of a square-top sail is attached at two points – the halyard at the forward end and a headboard car or short strop at the aft end – and the batten pocket, halyard and car all have to be engineered as one unit. It is one of the areas where sailmaker and rigger need to talk before the sail is cut.
Cruising and Racing Perspectives
A cruising sailor wants a head that hoists without snagging, drops without jamming and survives years of UV and flogging. A robust headboard, a bearing headboard car on a track system and a webbing strop rather than a hard shackle against the mast are worth their cost.
The racer looks at the head as a rating measurement and a control point. The mainsail head must not be hoisted above the black band; the headboard width is measured under most rules; and on a square-top sail the head width itself is a measured quantity.
Frequently Asked Questions about the Head of a Sail
How high should I hoist the head of my mainsail?
Until the top of the headboard is level with the lower edge of the black band on the mast, and no higher. Over-hoisting breaches rating rules and jams the headboard into the sheave box.
Why does my sail show wrinkles from the head?
Diagonal creases running from the head down the sail usually mean the halyard is too tight for the conditions, or the head fitting is skewed relative to the load. Ease the halyard a little; if the creases remain, have your sailmaker check the head patch.
The head is a small corner carrying the biggest load, and the whole sail hangs from it. Hoist it to the mark, keep its hardware and patch in good order, and the top of the sail will set as cleanly in its last season as it did in its first.