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Posted by on Sep 1, 2010 in Sailboat Racing, UK, US |

Shape of (America’s Cup) Wings to Come

The C-Class catamaran wingsails at the recent International C Class Catamaran Championship could point the way for some designers headed to the next America's Cup, if multihulls are chosen.

While Larry Ellison, Russell Coutts, and the BMW Oracle team that will defend the next America’s Cup are keeping their cards close to their chest until September 13th, they’ve shown a lot of interest in using multihulls again in Cup competition. And their skipper, James Spithill, took part in the International C Class Catamaran Championship—the successor to the “Little America’s Cup” which was the class championship for many years. The 2010 championship just concluded in Newport, R.I., and Spithill finished second as crew with countryman Glen Ashby as skipper aboard the Austalian entry, Alpha. Topping the field of six boats in the final results were the defending champions, Fred Eaton and Magnus Clarke of Canada, aboard Canaan.

Unlike the America's Cup, all competitor's rigs were stored together under a tent on the lawn of the New York Yacht Club.

Unlike the America's Cup, all competitor's rigs were stored together under a tent on the lawn of the New York Yacht Club. The fastest wings are at right, and the oldest, belonging to Patient Lady VI, is at left.

Although Ashby and Spithill won a couple of races early in the event, the brand-new wing belonging to Eaton’s Canadian entry proved faster when the wind moderated. I visited the venue and took these pictures towards the end of the regatta, which give you a feel for the kind of project boats these cats are. For some great action photos, visit the Little America’s Cup Facebook page for photos by Meredith Pierce Block, including a sequence of Steve Clark, a former champion, capsizing and falling through his wing. Unfortunately, that event put Steve on the sidelines for the duration of the championship.

Defending champ, Fred Eaton, examines his wing before sailing. Although all the sails must have the same area, designer Steve Killing had made the new wing four feet taller by reducing area down low.

Defending champ, Fred Eaton, examines his wing before sailing. Although all the sails must have the same area, designer Steve Killing had made the new wing four feet taller by reducing area down low.

The mast on the newer wings is inside the leading edge of the structure. Shown is the wingsail of Invictus, the British team.

The mast on the newer wings is inside the leading edge of the structure. Shown is the wingsail of Invictus, the British team.

A past champion, Patient Lady has an older-style mast which is integral with the leading edge.

A past champion, Patient Lady has an older-style mast which is integral with the leading edge.

How do you get at the sail control lines? The second Canadian entry, Orion, shows how. Just tear off the plastic.

How do you get at the sail control lines? Just tear off the plastic.

A heat gun seals up the wing covering on Alpha before racing.

A heat gun seals up the wing covering on Alpha before racing.

One of the remarkable aspects of the C Class is how open and accessible the teams were. The simple fact that all the wings were stored together exemplifies this.

Good thing plastic is easy to replace; Origin had shredded a bunch of it the day before.

Good thing plastic is easy to replace; Origin, the second Canadian team, had shredded a bunch of it the day before.

As a walk-on member of the press, I strolled into the tent early one morning and found the teams quite happy to answer questions and have me poke around and take pictures. Even though they had a race to prepare for that day. I’m not sure this open-door policy will be quite the same if a larger version of this sort of craft is chosen for the next America’s Cup, but I enjoyed it on this day!

I had a running Q&A with Rossi Milev, a top J/24 sailor from Canada who was working on Fred Eaton’s Canaan wing, reducing friction points, resealing the plastic wing covering, and making small adjustments. He described how the newer wings have masts inside their leading edge (see photo above) on which the ribs can float and therefore twist, providing a significant speed boost. He also told me they’d only had the new wing sailing five days before the regatta. I suppose that’s roughly equivalent to the fact that BMW Oracle had their wingsail for the Cup flying in San Diego only a couple of months before racing Alinghi with it on the Med.

There are more speed tweaks than meets the eye, Rossi said, pointing out that they’d switched from control lines made of Spectra SK90 to using PBO lines to reduce stretch. They also had a set of PBO shrouds in the trailer, but had decided they weren’t ready to test them.

The mast ends 10 feet below the top of the wing, and he pointed to the yoke (the control wings that stick out on either side of the wing at different heights) and said, in theory, on a windy day, they could invert the wing and thereby actually create righting moment. But again, testing the theory was for another day.

Rossi Milev applies clear packing tape, the C Class Cat sailor's equivalent of duct tape, apparently.

Rossi Milev applies clear packing tape, the C Class Cat sailor's equivalent of duct tape, apparently.

Polar chart on Canaan

Polar chart on Canaan

How fast do these catamarans sail? For a boat that’s only 25 feet long, the answer is, really fast! According to the polar chart at right, Canaan, the champion cat, should be able to sail close to 17 knots upwind and 24 knots downwind.  In the latter case, they sail without a spinnaker, which is all the more impressive. The boats actually jibe through about the same angles that they tack, roughly 90 degrees.

Would America’s Cup catamarans with wingsails really share the same design characteristics as these? Assuming that they’d have to carry spinnakers and upwind headsails, as BMW Oracle’s USA did, the answer is that they’d be different. The loading from those sails would require a lot more structure than the C Class’s relatively lightweight wings. But will the Cup design teams be going to school on these wings? You can be sure they already have, and plenty of potential challengers were represented in Newport during this event.

Canaan's carbon hulls are lightweight and low windage.

Canaan's carbon hulls are lightweight and low windage.