BLUE PAPER - Code Sails Defined

BLUE PAPER - Code Sails Defined

The name Code Zero means different things to different sailors. What started out as a straightforward but innovative concept, has evolved into an entire category of sails still under development. As a result, one Code Zero may look and perform quite differently from another, depending upon any number of design criteria. There is however one common theme amongst all the versions of these sails. Code Zeros are free flying, designed for close reaching angles, generally used between 40-90 degrees apparent wind angles and true wind speeds under 20 knots. To understand the different names and different versions of these sails, it helps to look back at their origin. Originally

Code Zeros were designed to qualify as spinnakers under various rating rules, which require the mid-girth to be 75% of the foot length. Multihull sailors called these sails Screechers, while Volvo Ocean Racers coined the term Code Zero - fitting below the standard coding convention established by North Sails of A1, A2, A3, etc. This design then became popular amongst many handicap racers under Rules like IRC, ORR and PHRF; and it remains a multihull standard. The greatest benefit of the Code Zero is adding a great deal of sail area and efficient sail power to underpowered, close reaching angles. Boats with non-overlapping headsails also see the biggest benefit from a Code Zero Asymmetric Spinnaker as the sail fills a large gap between upwind jibs and

downwind spinnakers. As the effectiveness and ease of use became increasingly apparent, the Code Zero’s popularity has expanded into cruising boats that benefit in much the same way. When considering a Code Zero type sail for your boat, it’s important to know your target wind angles, wind speeds and handling system, so that your sail can be customized to your specific needs. Depending upon these requirements, you will find a wide array of purpose-built Code Zero materials to choose for your sail. Here is a rundown of some of the names and styles of Code Zero’s which are now also commonly called Code Sails.

CODE SAILSDEFINED

BLUE PAPER: A North Sails Guide

BLUE PAPER - Code Sails Defined

Asymmetric Spinnakers - Spinnaker Mid Girth (SMG) >75%Code Zero Asymmetric SpinnakerUsed for rating rule racing, this sail remains much the same in concept as the original Code Zero. The design brief is the flattest possible sail with a Spinnaker mid-girth of 75%. The challenge of designing and building a Code Zero Asymmetric Spinnaker is that the girth requirement restricts how flat the sail can be; these sails have unsupported sail area that is not totally efficient in order to achieve the goal of light air, close reaching as close as 40 degrees AWA. This sail is typically made in a lightweight aramid laminate designed specifically for Code Zero applications. It will utilize an anti torsion luff rope with either top-down or bottom-up internal luff rope furling. A0/A3 Hybrid Asymmetric SpinnakerThis is another popular rating rule sail that tends to be more versatile than a pure Code Zero. The shape is halfway between a Code Zero and a A! or A3. It is commonly made in polyester spinnaker cloth and not necessarily used on a furler. The A0/A3 Hybrid will not sail upwind like a Code Zero, but it can cover a wide range of angles and conditions and proves extremely versatile on boats that may prefer to carry fewer spinnakers in their inventory

Sub Zero’s (SMG 50%-75%)Screecher / ReacherMany multihull racers will recognize a Screecher as a low-clewed, upwind Genoa type sail that sheets inside the upper shrouds. Some multihull rating rules like OMR specifically define this sail as having a mid-girth between 50%-75%. Cruising Catamaran sailors may view this sail as having a higher clew, fuller shape that sheets outside the upper shrouds. G ZeroThe G Zero Gennaker is the North Sails cruising version of a Code Zero. This sail is not restricted to the rating rule 75% mid-girth requirement and is therefore an easy to use and versatile sail. The G Zero Gennaker is appropriate for both modern and traditional cruisers; it can be made in a variety of materials and used with both furlers and snuffers.

Free Flying Genoas (SMG<50%)“Flying” sails are defined by the Equipment Rules of Sailing to be “set with no sail edge attached to the rig.” As a result, close reaching and upwind flying sails require High Modulus Luff Ropes and Anti Torsion Ropes for those sails set on furlers.

For some boats, which are not restricted by rating rule implications and where sail plan versatility is a premium, a variety of furling headsails and spinnakers may be set on either bottom-up or top-down internal torsion rope furling systems. This is especially true in offshore racing boats, where many of the sails called Zeros are in fact upwind or close reaching Genoas by design and performance. Any sail with a mid-girth 50% of the foot length is likely to have a Genoa shape and be used for true upwind sailing. However, in practice, these sails also get used for close reaching, so they are commonly and maybe incorrectly labeled Code Zeros by some who use them.

Masthead Zero (MHO) – Full Size, Full Hoist Free Flying Genoa for light air upwind use.

Fractional Zero (FRO) – Free Flying Genoa set on fractional halyard to reduce sail aspect ratio and reduce heeling force.

Blast Reaching Zero (BRO) – Blast Reacher set on a sprit. Sometimes used in a triple slot setup with a jib and staysail.