Code cracking

Nigel Sharp busts some myths as he investigates the evolution of code zeros and gets expert advice on adding one to your upwind sail inventory

- Nigel Sharp

Over the past 20 years or so, the term 'code zero' has often been mis-applied to describe a variety of large asymmetric sails used on different points of sailing. However, the generally accepted definition is that it is a sail which, under most racing rules, rates as a spinnaker but is set when sailing upwind in light airs and perhaps on a beam reach as it gets windier.

For IRC racers, they are especially useful for offshore and round the cans races.

Alan Harris-Guerrero of Sail Shape explains: “IRC yachts love these sails as they don’t affect their upwind/ reaching sail area on the IRC certificate, so in light to medium airs an IRC yacht with a small jib power-reaching can hoist a code zero giving a massive boost in sail area, especially if they are sailing too high to run their A3 asymmetric.”

For cruising, sailors are often uncertain as to which kind of sail is the best choice: is a code zero the smartest option or not? Mark Woodford of Jeckells the Sailmakers emphasises that it is important to first understand which sail is best suited for the type of sailing you're most likely to do. He explains: “A code zero is a flat free flying sail designed for close reaching angles. Many cruisers confuse code zeros with asymmetric sails, thinking they are for sailing downwind when really the benefit comes in increasing upwind sail area.”

Measuring up

Under IRC rules, and indeed World Sailing’s Racing Rules of Sailing, the difference between a headsail and a spinnaker depends on the mid-girth measurement as a proportion of the foot measurement: less than 75% and it is a headsail, which incurs a significant rating penalty for any area additional to that of the next biggest headsail; 75% or more and it is a spinnaker, for which there is no penalty as it will be smaller than a conventional spinnaker.