MAXIMUM SAIL POWER CHAPTER 8 ALL ABOUT SPINNAKERS - Part 3

Chapter 8 is a close-up look at spinnakers. A bit about the history of the spinnaker, different panel layouts, symmetrical versus asymmetrical and a whole lot more. In Part 3 we look at spinnakers by the numbers. It can get confusing because sailmakers are quick to drop a number thinking that you know what he’s talking about. Here is a quick guide. Note, however that some sailmakers have their own coding system.

SPINNAKERS BY THE NUMBERS Spinnakers have gone under countless names since the days of Niobe and Sphinx, but sailmakers started numbering spinnakers in earnest in 1998 with the development of a top-secret sail built for the Whitbread Round the World Race. Like most secret operations the sail was given a name reminiscent of something the

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CIA might have conjured up. Specifically, the sail was called a “Code 0.” Building on from the Code 0 are a number of other Code sails, a description of which is included below. In this particular example the even-numbered sails are for broad reaching and running. The higher the number, the more wind it is designed for.

Code 0

Membrane Code 0

The Code 0 was originally developed for the Whitbread Race where a restriction on the Whitbread 60 rule limited the size of the headsails. Because the boats were fractionally rigged they lacked power in the foretriangle, especially in light winds, and sailmakers were looking for a way to add some power without breaking any rules. They needed a sail that could perform like a headsail, in other words it could be used for sailing to windward, but one that was measured as a spinnaker. In order to be considered a spinnaker the sail had to have a mid-girth of at least 75 percent of the length of the foot. The mid- girth is the dimension from the mid-point of the luff

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across the sail to the mid- point of the leech. By creating a sail that looked like a headsail with a positive roach, the sail designers ended up with a sail that could be carried at very close wind angles while still being able to fly like an asymmetrical spinnaker when the wind came aft. Best of all it was measured as a spinnaker, not a headsail. Code 0 sails are actually closer to a giant headsail than they are to a spinnaker, and boats with small, non-overlapping jibs or fractional genoas will see the most benefit from a Code 0 because they are the boats that traditionally lack power in the fore- triangle. Boats with masthead rigs and large 155-percent genoas will see the least performance benefit, but since the sail is easy to set and douse they should definitely be considered by all sailors. One of the difficulties with Code 0 design is to come up with a shape that allows the sail to be used at fairly narrow wind angles. A flat sail is needed, but not so flat that there is insufficient camber to support the positive roach without flapping. The luff length is determined by the rig configuration and is usually as long as possible, running from the top of the mast to the end of the bowsprit (if there is one), or to the bow of the boat. The foot length is around half the luff length depending on the design of the boat. Since the Code 0 is a hybrid between a genoa and a spinnaker, it is usually made from a fabric that is also halfway between the two. A light film-to-film polyester scrim or a light membrane works really well. The fabric needs to be light enough so that the sail will fly, yet tough enough to take the loads without distorting. Code 0 sails are usually set on line- drive furlers, since the sails are flat enough that they can be rolled away and easily stowed. The line drive furlers have an anti-torque line that runs up the luff of the sail making it very easy to set and douse the sail. Simply pull on the furling line and the sail is easily rolled away. The anti-torque line also keeps the luff straight allowing the sail to be carried close to the wind. If the sail is not being set on a furler and does not have the anti-torque line in the luff, it will have a low stretch line like dyneema so that you can get good tension on the luff. If you don’t have a furler or don’t want to go to the expense of purchasing one along with the anti-torque line you can an easily set the sail in yarn stops; in other words it can be bundled up lengthwise www.greatcirclesails.com

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and tied with yarn so that when the sail is hoisted it won’t fill until the crew is ready, at which point a light tug on the clew breaks the yarns and the sail fills with air. The sail is dropped the same way as you would a spinnaker. Depending upon the fabric and boat design, the Code 0 can be carried from as close as 45 degrees apparent wind angle (AWA), to as wide as 75 to 80 degrees. At this point, however, other sails are more efficient. A final point about the Code 0: Because this sail is a hybrid between a spinnaker and genoa, tending more toward the headsail, it generates headsail-type loads. If the sail is going to be set from a bowsprit, be sure that the bowsprit is strong enough to manage the loads, since usually bowsprits are engineered to handle the more benign loads of spinnakers. The same applies to your mast. The amount of halyard tension required to keep the luff from sagging places a large compression load on the mast for which it may not have been engineered. Often mast manufacturers will require a 2:1 halyard for the Code 0 to minimize mast compression. In sum, this is a powerful sail and should be treated accordingly. Code 1 This sail is usually the first to take over from the Code 0 and is a specialized sail designed to fill the gap for when the winds are at an apparent wind angle of between 70 and 120 degrees off the bow.

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This sail closely resembles the asymmetrical reaching spinnaker used by most cruisers. Made from nylon, the Code 1 is a light, versatile spinnaker that can be set and doused with a spinnaker sock if cruising, or in yarn stops if racing. It is usually shorter on the foot than an all- purpose asymmetrical spinnaker and has flatter chord sections to allow it to be carried closer to the wind. Again, depending upon the design of the boat and the number of other sails in the inventory, this sail will usually be made from a fairly light nylon, reinforced along the leech and with oversized corner patches to take the increased load experienced when reaching.

Nylon Code 1 Code 2 The Code 2 is a light–air, running spinnaker with a wind range between 105 and 155 degrees AWA. Larger and lighter than the Code 1, this sail has a lot more chord depth for the broader wind angles. It’s an ideal sail for a cruising sailor who is used to starting the engine when the wind gets light. It’s easy to set and douse with a sock, or with stops if the sail is part of a racing inventory. www.greatcirclesails.com

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Code 3 Similar in design to the Code 1, but built from a heavier fabric, the Code 3 has a wind range of 75 to 130 degrees AWA. This sail is useful for racing boats with crew weight on the rail or water ballast, or for cruising boats with a high righting moment. For most cruising sailors, a heavy reaching spinnaker like the Code 3 is not practical. The sail can unduly load the mast and rigging, and if not trimmed properly, can drag the boat sideways as much as forward.

Code 4 This sail most closely resembles the asymmetrical spinnaker found on many cruising boats. As an even-numbered sail it is used for running, and its high number indicates that it can be used in stronger winds. If the Code 4 is part of a racing inventory, the shape will be narrowly defined to fit between the other spinnakers on board, while as a cruising sail it will be more forgiving. The Code 4 has a wind range between 105 and 155 degrees AWA. Code 5 This is a specialized sail for heavy-air reaching, and like the Code 3 is specifically a racing sail. Smaller in size than the other spinnakers, it is strong and forgiving. The Code 5 can be used between 100 and

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140 degrees AWA. Again, the Code numbering system applies to both asymmetrical and symmetrical spinnakers, and is described here to show how different sails are designed to meet different needs and conditions. Some sailmakers will have their own system, and nothing is cast in stone. These are broad references only and the individual sails will be tailored to suit each particular boat. Sail designers take into account the aspect ratio of the rig, the righting moment of the boat, class rules that restrict or limit the number of sails, and many other criteria. Top Down Furling Top-down furling units are becoming more and more popular and they work great. Many sailors are intimidated by their spinnakers and even find that setting the sail with a dousing sock a little daunting. Hardware makers have taken note and have come up with a very user friendly furling device. The top-down furler also use an anti-torque line to set and douse the sail only this time the line is

Top Down furler - you can see the anti-torque line separate from the sail itself

not part of the sail. In other words there is no line in the luff of the sail like the one found on the Code 0. Instead the anti-torque line runs separate from the spinnaker. It runs from the furling drum to a swivel which is attached to the halyard. When you want to douse the sail the furler transmits to the swivel and the head of the sail (hence the name Top-down) starts to wrap around the antitorque line. It collapses the spinnaker as it furls allowing the rest of the sail to be wrapped around the anti-torque and rolled away. A note of caution. This furling units have made it very easy for sailors to manage spinnakers, so easy that some sailors have become complacent and will leave the sail hoisted rather than dropping it to the deck while motoring in light winds. I have read of at least one time that the spinnaker halyard chafed through and the whole thing came down and ended up around the prop sharp. A very messy situation I am sure.

I hope that you enjoyed this blog. There are many more at my website www.greatcirclesails.com. If you need new sails for your boat just click this box and I will send you a no obligation quote.

BRIAN HANCOCK Owner Great Circle Sails