jib

A jib is a triangular sail mounted on a stay (a wire or rope running from the mast to the bow or bowsprit) in front of the foremast. On a sloop or cutter, it overlaps the mainsail slightly or reaches back toward the mast depending on cut and rigging. The jib provides drive and, critically, helps the boat sail closer to the wind by accelerating air over the lee side of the mainsail, a phenomenon sailors call the slot effect.

Jibs come in several working varieties. A working jib is the smallest and strongest, used in heavy wind; it typically has a high clew (upper aft corner) so it does not flog in rough seas. A genoa or overlapping jib extends well back past the mast, offering more area and power in light to moderate winds but requiring a boom preventer and careful handling on the reach. A storm jib is tiny and heavily built for survival conditions. A yankee jib sits higher on the mast and does not overlap, used aboard larger vessels and work boats where overlap would interfere with other gear.

Why the name and where it sits in rigging

The term jib likely derives from the verb "to jib," meaning to shift or move suddenly, though some argue it comes from the Latin gibbus (hump), describing its curved shape. On fore-and-aft rigged vessels, the jib is the primary foresail; on square-riggers, the fore course and fore-topgallants occupy that role, and jibs are used only for fine steering and running before the wind. The stay on which a jib hangs is tensioned to shape the sail and keep the spar (mast) in column.

The jib hanks onto its stay via small metal or plastic rings called hanks, or (on modern racing boats) via a groove extrusion called a furler. Hoisting and lowering is done from the deck via a halyard running up the mast to a block at the top. The foot is controlled by the jib sheet, a line running back to a cleat or car on the deck. Trim angle and tension must balance the mainsail trim to avoid weather helm or excessive lee helm.

In heavy weather, jibs split and tear along the leech (trailing edge) or fail at the head; the most vulnerable point is where the halyard eye sits, which concentrates wind load and flexing. Modern cruising jibs often use laminate or tri-radial panel layouts to resist fatigue. Storm damage is common; a split jib must be furled or lowered to prevent the tear from running across the sail and compromising the stay.