The advent of Code Zero sails more than 20 years ago set off a revolution in offshore raceboat performance. Paul Cayard’s team on EF Language in the 1997-98 Whitbread Round the World Race, with North Sails, is often credited with the first high-profile development and use of these sails, helping them take the overall victory in the race.
Meanwhile there were parallel and more-modest efforts being made elsewhere in the racing world, including Denmark, at the hands of Elvstrøm Sails CEO Jesper Bank.
“We were having a good time sailing locally in a 34-foot boat of mine that we kept trying to supercharge with more and more sail area to get through the typical light air of these races,” says Bank, an Olympic gold medalist and America’s Cup skipper. “We had this idea of building a Code Zero, which was just the talk of the very elite of sailing in those days. Not many knew what such a sail would even look like, and for sure no real sailcloth existed for it.”
He and colleague Ken Madsen happened upon a few rolls of a bright-yellow, light laminate. From this, he says, they built what they believe was the first Code Zero in Denmark and used it in a 137‑mile distance race around the island of Fyn.
“We were lucky we could fly that sail for 40 percent of the race, and that gave us a first in class, and if I recall right, third to finish after some of the much bigger boats in Denmark,” Bank says. “It was fun to be at the leading edge.”
From the start, it became clear that when the conditions matched the range where these sails could be used, the boat became turbocharged and disappeared over the horizon.
The reason for their effectiveness is simple: These masthead-reaching sails fit perfectly into an important niche in the sail-selection matrix—where fractional, nonoverlapping jibs can’t provide enough power and asymmetric spinnakers are too powerful.
As these sails have evolved in design and use, it’s become surprising how large an area they can occupy in the selection chart: from a relatively narrow range of tight-reaching angles in light air to expand rapidly as the breeze strengthens.
An important aspect in their development was how to design them so that they fit within existing class or handicap-rule frameworks. Because they have a free-flying luff, Code Zeros do not fit the definition of a headsail whose luff is attached to the headstay, so they therefore had to somehow fit within the definition of a spinnaker.
In the Whitbread 60 Class, the definition required the sails to have a midgirth dimension of no smaller than 70 percent of the foot length, in Denmark; in the DH rule, it is 65 percent; so these became the lower limits in size and flying shape available to sail designers.
Many rating-rule authorities set their minimum girth definitions at 75 percent to impose some limits on the new sail’s development path and range of effectiveness. At this relatively large size, only boats with stout rigs to handle the loads and a robust righting moment could push the sail toward tight headsail angles, and when used at broader angles; then the A3 as the conventional reaching spinnaker would be considered.
However, such limitations did not stop development at the grand-prix level, where an increase of speed at any cost is fair game for exploitation. In classes such as the Maxi 72s that race in venues where there is plenty of non-VMG sailing around islands and the like, a properly developed masthead Code Zero could easily become a race winner.
The challenge, however, has been to meet the minimum-girth requirements and still have an effective flying shape and stability in the angles between the headsail and the A3. With a tight luff, the shaping geometry becomes difficult without having extra sail on the leech.
At tight sailing angles, this extra sail area could not be flattened enough because of the minimum amount of girth needed to meet the rule.
Various tricks were devised to try to reduce the annoying flapping leech that was stealing laminar flow off the back of the sail. Some teams resorted to building fractional Code Zeros (“Fr0s”) to fill this niche at tight angles where the masthead sails were too deep and too powerful.
So, two Code Zero sails were becoming part of what was already a highly complex choice of reaching sails available to the offshore racing yacht: a masthead Zero or A3 spinnaker for broad angles; a Fr0 for tighter angles; a jib top; a blast reacher; or a genoa staysail for even tighter angles. Some teams are even experimenting with a high-clewed flying headsail flown off a tack pennant on the bowsprit to make it three sails forward of the mast: the reaching headsail, the upwind headsail and a small reaching staysail.
Imagine the groans over the cost and complication, not to mention the bulk and weight of all these sails. Not many racing programs can handle this load.
Then came a flash of inspiration: Why assume a tight luff is needed for an efficient Code Zero flying shape?
In the past year or so, sail designers have shifted their thinking to explore flying shapes that allow the luff to sag more than a sail whose luff is supported by a tight cable.
This change in geometry is accompanied by reconsidering the structural elements of the sail to better accommodate the loads within the sail itself. With fiber-reinforced cloth, this becomes a matter of laying in enough carbon and aramid to match the loads calculated through an analysis of the stress vectors in the sail.
The loads are determined by the size of the boat and its stability, as well as the size of the sail itself, and the max loads it sees varies with wind speed and angle.
“By placing high-strength fibers along the catenary load lines,” says Glenn Cook, of Doyle Sailmakers, “we can achieve great strength and stability for the desired mold shapes. This has also allowed us to better flatten the exit shapes for more efficiency” and reduce that annoying flapping of the first‑generation sails.
JB Braun of North Sails points out that custom-designed sails built with tapes or fibers are not necessary for building good Code Zeros, thereby offering a solution for those more budget-conscious owners interested in this performance upgrade.