Choosing Code Zero: Which type is right for your boat?

​Anyone sailing close to the wind on a modern yacht has little to complain about: the non-overlapping jib can be sheeted in tight, and the boat maintains good headway and speed. But when you bear away, you’ll wait in vain for pressure. The sail twists and provides hardly any propulsion. It lacks both area and profile. The Code Zero fills this gap. On average, it offers two to two-and-a-half times the area of a standard headsail and is one of the most efficient tuning measures for modern rigs.

From regatta sailing to the whole sailing family

Code Zeros first appeared in the 1997 Whitbread Race. A large, free-flying headsail, formally measured as a gennaker, but in practice a huge calm-weather genoa. Since then, the concept has evolved from a regatta sail designed to exploit the rules to an entire family of sails for regatta yachts and, above all, cruising yachts. In other words, there is no such thing as ‘the’ Code Zero. This is also reflected in the nomenclature used by sailmakers.

Quantum, for example, refers to them as Apparent Wind Sails, or AWA for short, and has three standard types in its range. Elvström names its models Code 53 to Code 75 and offers a total of seven types. Like Elvström, UK Sailmakers bases its design on the sail’s mid-width and refers to Code 55 or Code 65, although the actual mid-width is tailored to the boat and the owner’s preferences. North Sails also uses designations such as Code 55 and Code 65. It’s confusing.

The width at the centre determines the size and range of applications

The centre width is defined as the shortest distance between the luff and leech at half height, expressed as a percentage of the foot length. It determines the size, profile and range of use, and thus which sail is suitable for which sailor and boat. However, standard sail codes today range from 53 to 65 per cent. This results in versatile sails with good close-hauled performance, which can be used right up to the medium reach range, depending on wind strength and boat type.

The narrower the centre, the more easily the sail rolls and the closer to the wind it can be used. Conversely, the wider the centre, the fuller the sail becomes and the further its range of use shifts towards that of a gennaker.

From 75 per cent of the centre width, the sail is classified as a gennaker for measurement purposes. This is relevant for regatta sailors, as narrow codes count directly towards the ORC upwind performance and can have a significant negative impact on the rating. For cruising yachts, such large codes are rarely an option, as they quickly overwhelm the crew and compromise stability, and are too rarely used.

The problem with classifying sails by centre width is that most non-sailmakers find the figure difficult to interpret and often do not know the centre width of their own sails.

​Types and areas of application

The Quantum designation based on the apparent wind angle (AWA) is somewhat more intuitive and can also be applied to sails from other manufacturers. An AWA 40, for example, is designed so that it can be sailed particularly close to the wind. It is therefore very flat and rather small. The mid-width is around 50 to 60 per cent. For most recreational sailors, it is too specialised a sail, offering few advantages over the standard headsail.

An AWA 60, with a mid-width of 60 to 70 per cent, is significantly larger and more versatile. Sailmaker Sven Krause from Quantum Sails recommends this variant for most boats: “We use a sail like this on our Comfortina 32 in winds up to 12 knots; from an angle of attack of 55 degrees, if you bear away further, you really start to make good headway.”

With a centre width of 70 to 80 per cent and an operating range of 80 to 130 degrees apparent wind, the AWA 80 is the widest sail in the Code Zero family. The sail is easy to hoist and furl in all conditions and places hardly any demands on the trimmer or helmsman.

For those who don’t want a gennaker, the AWA 80 offers a robust compromise that covers everything from a light reach to close-hauled sailing. “We recommend this design for older crews or shorthanded sailors who no longer want to be clambering about on the foredeck and changing sails,” says Krause. However, anyone hoping for maximum upwind performance with a Code of this type is mistaken.

Selection guide for Code Zero

​These figures are provided for guidance only. The centre width alone does not determine the range of use. Tread depth, sail area, material, luff construction, and the shape and stability of the boat also play a part.

Hull stability and standard headsail

When determining the design and size of the sail, it is not only the intended use that is important, but also the type of boat and the hull’s stability. Modern yachts with a wide waterline can carry considerably more sail area and use the sail even in stronger winds and on tighter courses. Søren Hansen, sail designer at Elvström Sails Denmark, comments: “Boats such as the Hallberg-Rassy 50 or the HR 69 sail with a Code Zero up to 70 per cent of the time, because their hull stability allows them to use the sail even in stronger winds and on very close-hauled courses.”

A more slender boat quickly reaches its limits with a large Code Zero and performs better with a slimmer sail, according to the Danish sailmaker. Anyone who already has a large, overlapping genoa on board won’t gain much from a Code Zero. The smaller the standard headsail, the greater the difference.

In the Article about the Basics of using and handling the Code Zero explains the advantages this sail offers, particularly on yachts with a small jib or a self-tacking jib.

Material: laminate, membrane or nylon

On large yachts, you sometimes see stylish, translucent membrane Code Zeros. For most applications, however, triradially cut laminates are sufficient. “We have no trouble making sails for 60-footers from aramid laminates,” says Krause. For the deep profiles required on cruising boats, this often works better than a membrane.

You should be wary if a nylon fabric is offered. “At best, that’s a reacher. You can sail on a half-wind with it, but it’s nothing like a proper close-hauled sail. The material is cheap, but it stretches far too much,” says Krause.

A cable is good for winding, but not for trimming

The Code Zero is set to fly freely and is almost always combined with a continuous-loop roller. The luff has to withstand considerable forces. There are three fundamentally different approaches to choose from. The term ‘cable-free’ covers two of these, which can cause confusion.

The classic variant is a torsion cable threaded through the luff. This is almost always a PU-impregnated Dyneema line, which provides stability to the luff and allows the sail to be rolled up tightly. These cables are tried and tested, durable and allow the sail to be rolled up tightly. However, they also have disadvantages: the stiff cable limits trimming options and affects the sail’s profile. Furthermore, on close-hauled courses, it requires a great deal of halyard tension to prevent the sail from sagging too much to leeward, and it increases the weight of the sail. A hindrance when stowing: when rolled up, laminate sails and cables turn into a stubborn sausage that requires a long bag.

What makes Cableless systems different

The alternative is what are known as ‘cableless’ systems, in which carbon or aramid fibres run through the luff from the throat to the head and bear the entire longitudinal load. These are often membrane constructions. Without the cable, the luff can be cut with a slight forward curve. As a result, the sail projects further to windward whilst reducing the tension in the halyard, and sags less. With the correct trim, a cableless code can cover a wider wind angle. Furthermore, the sail is lighter and has a significantly smaller pack size.

For cruising sailors, however, it is not necessarily the best choice, despite all its advantages. “The cableless concept is difficult for many. Once hoisted, the sail behaves much more dynamically, almost like a gennaker. It requires either more attentive trimming or more attentive steering. Autopilots cannot keep up with this dynamic behaviour in the same way as with a cable-equipped sail. In choppy seas and freshening winds, you have to sail five degrees lower than is theoretically possible, otherwise the sail will kill the boat,” says Krause.

Another disadvantage is that, without a stiff cable, the sail does not roll up compactly enough at the top to remain set permanently. There is no price advantage. What is saved on the cable has to be invested in construction and materials. Ultimately, the cable-free sail is often even more expensive.

Hybrid solutions combining wired and wireless technology

A hybrid approach has become established between traditional cable systems and fully cable-free systems. North Sails calls this technology ‘Helix’, whilst UK Sailmakers refers to it as ‘ISL’, short for ‘Integrated Structural Luff’.

As with a cable-free system, reinforcements in the luff and the sail itself bear the longitudinal loads. The cable is thinner or omitted altogether. Aerodynamically, the hybrid solutions offer similar advantages to cable-free codes.

With reduced halyard tension, the luff projects to windward. The code sits better on deeper tacks and is less obscured by the mainsail. The structures integrated into the luff are also designed to make furling easier.

A comparison of design types

​What requirements apply to the rigging and deck?

Before deciding on a sail, it’s worth taking a look at your own rig. Is there a usable halyard above the forestay? On top-rigged boats in particular, there is often no space in front of the stay to hoist a furled Code. 7/8 rigs also present difficulties. Above the forestay, the mast is often too tapered to support the spinnaker safely.

There must also be sufficient space on deck. The attachment point for the furler should be at least 20 centimetres in front of the forestay and must be securely anchored. If you’re using an existing spinnaker halyard routing, you must ensure there’s a deflection point below the halyard locker. Without a guide, the halyard sheave will be subjected to an uneven load, which usually leads to problems.

From around 43 feet, a 2:1 halyard system is virtually unavoidable with a cable code. With hybrid systems featuring a well-designed luff, however, the required tension remains within reasonable limits. In any case, it is important to use a low-stretch halyard, which is best left on the winch whilst sailing. A continuous furler with a backstop is also essential equipment. “It’s a real game-changer,” says Krause, “especially for people who tense up when pulling.” Anyone who has ever experienced a Code Zero unrolling when re-gripping it will never want a furler without a lock again.

A Code Zero or two light-wind sails?

Two sails are ideal: a Code Zero with around 60 to 65 per cent of its centre width for close-hauled courses, and a full A2 gennaker for broad reaches. The A2 is in its element on courses around 155 to 160 degrees to the true wind and sits calmly and stably. “It looks after itself,” says Krause.

If you only want one sail, choose a Code with 65 to 75 per cent mid-width. It covers an astonishingly wide range of conditions and can be sailed in the butterfly position on very broad reaches.

The differences between the various headsails and full-sail types are set out in the A guide to sailing attire for cruising yachts classified in more detail.

Book recommendation

Sail and rig trim By Ivar Dedekam, this book explains the aerodynamic principles and practical trimming of the headsail, mainsail, spinnaker and gennaker. More than 150 colour illustrations show how adjustments to the sails and rigging alter their profile and performance.

Slim and sporty or wide and straightforward: which Code Zero is right for you on board? Join the discussion.