Downwind sails
Code zero
A flat, genoa-like flying sail for light-air close and beam reaching — cut with just enough mid-girth to measure as a spinnaker under racing rules.
Angles off the true wind where this sail typically flies. Wind from the top; the port side mirrors.
3–18 kn true windTypical teaching range — the right number is always boat-dependent.
Hoisting & setting
Set flying on its own luff: a torsion cable (anti-torsion rope) inside the luff transmits the twist from a continuous-line furler, so the sail rolls up and unrolls in place. The tack rides a tack line at the bow or bowsprit, the halyard is wound on hard, and the luff is tensioned straight and tight — trimmed like a genoa, not like a spinnaker.
Cloth & construction
As flat as the sailmaker can cut it, yet with a mid-girth (half-width) of at least 75% of the foot length — the racing definition of a spinnaker. That girth exists purely to satisfy the measurement rule: without it the sail would rate as an oversized genoa. The result is the defining code-zero compromise — spinnaker girth on paper, genoa-flat shape in the air, built in light, stable cloth.
Handling & trim
Fills the gap between the genoa and the spinnakers: light-air close reaching to beam reaching, typically in around 3–18 knots true. In very light air some boats carry it to about 40–45° to the wind, easing to a beam reach and beyond as the breeze builds — every figure boat-dependent. On most cruisers, treat it as a light-air reaching sail rather than an upwind sail, and furl it before the breeze loads it up.