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Sails for the Circumnavigator - Multihull Edition

Circumnavigation is no easy feat. It requires a boat, sails, and hardware that all stand up to the elements. In Sails for the Circumnavigator, Quantum’s Dave Flynn examined sail options and materials for a Passport 545 and a Valiant 40. In the multihull edition, Dave applies the same thought process to a typical mid-sized catamaran, using the Helia 44 as a model. Much of the information is the same, though there are a few subtle differences with multihulls. Read on for Dave’s recommendations and insights on what to consider when building an inventory for circumnavigation on a multihull. 

Multihull Case Study: Helia 44

 

Mainsail

The mainsail features a large roach profile with approximately 14 percent more area than a conventional monohull sail with a backstay constriction. I don’t know if I would go to a square top setup as diagrammed in the sail plan. This setup is fashionable these days, but it creates some issues. The first is dealing with the diagonal required to support this profile in the head when the sail is down. There is a clever fitting that allows this batten to be swung into place when ready to hoist, then relaxed so the sail can be flaked properly. The other issue is bias stretch. I would not recommend woven polyester (Dacron) for a square head mainsail. There is too much concentrated bias loading in the head, which will make woven materials distort. Composites, in which fiber can be introduced specifically to accommodate the head loadings in a square top, will work. In either case, proper battens that are stiff are absolutely necessary. In reality, a more conventional roach profile can provide the same area and somewhat simpler setup. It will also make it easier to control twist. Again, with woven polyester, I wouldn’t set up the roach profile any other way (More on materials to follow.).

Battens are a key element in any mainsail, and the bigger the roach the more important they become. Standard round rod battens work okay, but there are stiffer alternatives that better support the roach over time. RBS and C-Tech are two companies that make high-quality batten alternatives. They add cost but are worth considering if you’re expecting a sail to hold its shape for the long haul.

Three reefs are necessary with a typical catamaran roach profile. I wouldn’t bother with a storm trysail, just a very deep third reef. Proper luff hardware, offered in track systems from Harken, Antal, and Fredrickson, is a must since the sail will use five to six full-length battens.

Genoa

The genoa is a straightforward sail, with its geometry constricted by limited sheeting options. Cruising catamarans typically have relatively small headsails, so one sail pretty much does it all. However, it would be nice to have a proper storm jib or small solent style jib as a heavy air alternative. Since changing sails on the fly is difficult when sailing short-handed in heavy conditions, it would be great to have this sail on a separate, removable stay such as the Gunboats typically do. I know most cruising cats are not set up with the structure to support an inner forestay, but it would sure be nice!

Materials for Upwind Sails

There are three material choices: classic woven polyester, various tri-radial options, and composite membrane construction. The trade-off among them is cost versus shape life. Ultimately, any choice should be similarly rugged. Woven polyester or one of fortified woven fabrics such as Hydranet or Fibercon may remain intact longer as a triangle, but the sail shape will have given up the ghost long before ultimate failure. Introducing fibers with composite construction, such as Spectra, carbon, Vectran, or aramids, reduces stretch. Sail shape is all about stretch. If a sail is going to remain flat and draft forward and the leech is not going to become elongated, stronger components are necessary. A carbon/Technora membrane sail will have five to eight times the stretch resistance that a woven sail does. The sail will have a significantly better sail shape initially, and in five years there will be no comparison. The composite sail will look virtually new.

Woven Materials

All top cloth makers (Contender, Bainbridge, Challenge, and Dimension) provide various grades of woven polyester, distinguished primarily by their stretch characteristics. The lower the stretch, the higher the cost. Typically, each manufacturer refers to their top-of-the-line options as HA (high aspect). The only downside to these fabrics is that the same relatively small fibers that allow for a dense weave and low stretch also burn up more quickly in the sun. For extended cruising applications, some additional stretch is the penalty for using slightly larger yarns that maintain their tear strength over time. All woven sails here are specified with Contender Supercruise. Comparable products include Challenge HMW, Bainbridge Ocean Premium, and Dimension Heavy. All could be specified with HA fabrics if better performance is the primary design criteria.

Composite Materials

Composites for cruising sails have come a long way since introduced in the mid-1980s. The latest generation of membrane style construction effectively eliminates the paneled jigsaw puzzle approach with a one-piece integrated fiber network that addresses sail loadings holistically. Issues of de-lamination have largely been addressed with advances in lamination technique and adhesives. Composites offer dramatically better shape life and gains in initial performance, particularly as the boat size and loads increase. There are no sails for boats over 65 feet that aren’t constructed of composite material. This is proof of the viability of modern membrane composite construction.

Tri Radial Options

There are various pre-made materials available to use in paneled tri-radial constructions that could be considered, including Hydranet, Fibercon, and Radial Dacron. Hydranet, a spectra-reinforced woven material, has been used in this application with success. It makes a durable sail with slightly better performance and has no mildew issues, though round-the-world sailors won’t typically have mildew issues because their sails are in constant use.

Reaching and Off-wind Sails

With any luck, reaching and running are the points of sail where you will spend most of your time. While a genoa is a better reaching sail than a small jib, a Code Zero is a much better reaching sail. A careful balance of size, shape, and lighter material make a code sail much more useful, and a conventional furler makes it totally reliable and easy to use. The Helia 44 is set up with a short sprit for this type of sail. For broad reaches and runs, there is no substitute for an asymmetrical spinnaker. With the Code Zero always available, I would go for a full-sized A2 runner optimized for the broadest angles possible. Cruising catamarans are not speed demons and do not pull the apparent wind forward significantly when compared to their monohull brethren. You need to be able to broad-reach. Two hulls allow the use of additional lines to the tack of the sail to pull it around to weather, making it particularly effective. Some cruising cats actually use a symmetrical spinnaker controlled from either bow for dead downwind sailing. An ATN spinnaker sock would still be my choice given their simplicity and reliability. Top-down furlers are also an option, but consider their pros and cons, particularly for a large-girth running sail.

Summary

If it were me, I would have a Fusion MC Carbon/Technora mainsail, genoa with C-Tech carbon battens, Screecher/Code Zero made of either Fusion MC Technora or a tri-radial paneled sail of Dimension CZ 30. I would round out the inventory with an A2 asymmetrical made out of Dimension AirX 700 nylon. Finally, I would use a furling solent on a torsional luff rope out of Hydranet or Fibercon.

Of course, since I am only playing this as a virtual fantasy game, I have no budget!



 
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