Racing Flying Sails
Until recently, there were only two types of reaching sails: headsails and spinnakers. A headsail was defined by the rules as having a mid-girth measurement less than 75% of the foot length, while a spinnaker had a mid-girth of 75% or more. In 2018, the ORR handicap rule introduced a new class of sails called “large roach headsails” or “tweeners,” with mid-girths between 50% and 75% of foot length. More recently, the ORC and IRC rating rules followed suit, referring to these sails as flying headsails. The IRC definition is slightly different, requiring a mid-girth between 62.5% and 75% of foot length.
For yachts with overlapping genoas, the performance gap between a genoa and a flat spinnaker on reaching angles has historically been narrow. Over the years, yacht design evolved from masthead rigs with overlapping genoas to fractional rigs with smaller or non-overlapping jibs, driven by efficiency and rating advantages. While non-overlapping jibs perform well on windward-leeward courses, these boats often lacked optimal overlapping sail area for tight reaching in distance races.
Several sail options now fill that reaching gap on boats with non-overlapping jibs. These include the flying jib (a non-overlapping topsail flown in front of the headstay), the flying headsail, and the code zero. The main difference between a flying jib and a flying headsail is size: the flying jib is no larger than the boat’s largest-rated headsail, while the flying headsail is slightly bigger, with a mid-girth that fits within rating rules. Essentially, this new sail type measures between a code zero and a headsail. All major rating rules, including IRC, ORC, ORR, and PHRF, allow and rate these sails, though interpretations vary slightly.
For sailors seeking maximum performance, ISL (Integrated Structural Luff) technology can be added as an upgrade to select new X-Drive® and Titanium specialty headsails, as well as code zeros.
The polar diagram to the above shows the Large Roach Headsail (purple line) fills a gap on some boats between jib and spinnaker at close-reaching angles. In this sample, the LRH provides the fastest solution between 65 and 90 degrees true wind angle.
The flying headsail is flatter than a code zero, taking on a shape more like a traditional headsail, and features a positive roach. The clew sits below boom level and the sail is normally sheeted behind the keel; in most cases, the optimal sheet position is forward of the genoa winch. It must be tacked forward of the forestay. We recommend a top-down furling system to handle the roach and achieve a tight furl. This allows the sail to remain furled on the bowsprit, making transitions between flying sails and standard headsails quick and easy.
The measurement rules for flying sails are complex, introducing new measurements to the IRC and ORC rules. The sail must be measured both as a headsail (to determine area) and as a spinnaker (to determine the mid-girth ratio). Under IRC and ORC, flying headsails must be set forward of the forestay, with a mid-girth between 62.5% and 74.9% of the foot length. Under ORR, the mid-girth must be greater than 50% but less than 75% of the foot length.
Your local UK Sailmakers loft can determine the optimal mid-girth for your boat. Your sailmaker will recommend a properly sized sail based on the races you plan to enter, your current sail inventory, the boat’s stability, and the expected rating impact. In general, a smaller mid-girth allows the flying headsail to be designed flatter for improved performance.
IRC Rule For Calculating Area (HSA & FSA):
- HSA = 0.0625*HLU*(4*HLP + 6*HHW + 3*HTW + 2*HUW + 0.09)
- FSA = 0.0625*FLU*(4*FLP + 6*FHW + 3*FTW + 2*FUW + 0.09)
Flying Headsails are mainly used between 50 and 125 degrees TWA, which are reaching angles. Moreover, they truly stand out on planing boats with reaching struts or whisker poles that allow the sails to be sheeted away from the mainsail. Reaching struts or whisker poles open the slot between the main and the flying headsail. As the boat speed increases, this sail just gets faster and faster as your TWA comes forward.
Above are three views of the flying jib set outside a J3 on the XP44 WOW.
For most production racing boats, the flying headsail represents a significant rating penalty and often isn’t worth the investment. However, for lightweight planing boats like C&C 30s, Fast 40s, Open 40s, and TP52s, a flying headsail used with a reaching strut is an excellent option because these boats can move their apparent wind forward quickly and build speed effectively with this sail.
For the majority of boats, the flying jib remains the best choice. It is the same size as your headsail and can be flown off the bowsprit. Under IRC, the flying jib is still “free” rating-wise and can add an extra knot or more when close reaching. It is flat, easy to furl, and convenient to leave on the bowsprit, making it the go-to option for most boats.
In summary, if you’re racing a production racer or cruiser, stick with the flying jib and code zero. For fast or foiling yachts, or for long offshore races that include a lot of reaching, the flying headsail can be worth the investment.