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2013 Fill Your Hands
In response to the 2013 America's Cup the C-Class competitors began developing daggerboard foils that would lift the boats clear above the water. We had designed a foiling boat back in 2007 called Off Y’er Rocker that was a successful foiler, but not fast enough to beat our other displacement boats.
Fill Your Hands was designed to experiment with various new foiling techniques. It is easy to fly a boat, but difficult to keep it under control when flying - especially in a two man boat when there is little time to dedicate to flight control. Experiments with C-Foils, L-foils, and J-foils were progressing well, but time ran out before stable flight was achieved. Fill Your Hands ranked 3rd at the 2013 International C-Class Championship in Falmouth, England.
Canaan was designed for the 2010 Little America's Cup Event in Newport, R.I. Hull shape development for this boat led to less wetted surface and a more gradual run aft than Alpha. For more efficient control we moved the rudders under the hulls. The sailplan is taller and shorter on the chord which provides less drag and a smaller tip vortex and secondarily allows the crew to fly a hull earlier. Piloted by owner Fred Eaton and wingman Magnus Clarke she was the winner of the 2010 ICCCC (formerly known as the Little America's Cup) beating her sistership Alpha, sailed by the Australian team of Jimmy Spithill and Glenn Ashby.
Orion was developed in 2009 to experiment with low volume bow shapes. The wing, crossbeams and rudders were all produced from existing tooling from Alpha. At this time we were realizing that the top end speed of these boats is reached at the relatively low wind speed of 10 knots and were looking for ways to increase that speed in the higher wind range. As the sea state increases with more wind, could we reduce the drag of the hull by fining up the bow and reducing the pitching of the hull? Now that we were using winglets on the rudders, the tendency of the bow to dive when pressed hard was less of a problem.
These hulls were clean in their entry into the water but were too fine, in retrospect, and even with the help of rudder winglets could not provide enough buoyancy forward in high winds.
One of the more interesting experiments of our C-Class campaign was the creation of the hydrofoil-borne C-Class cat, Off Yer Rocker (an appropriate name on two levels).
As newcomers to the class, we were surprised to learn that the top speed of C-Class cats was limited to around 22 knots. Our helmsman and project leader, Fred Eaton, previously had been focused on skiff racing, most of it in International 14s, with a couple of seasons racing 18 footers which frequently exceed the C-Class maximum speeds. It seemed odd to him that boats as fast around the course as C-Class cats had such a “low” top speed, and with naïve enthusiasm we thought that was an area for improvement. From the first days of the campaign, Eaton was determined to try to do so.
After looking at the merits of T-foils, L-foils and full width foils, we decided to model our approach on the T-foil system with wand control that had proven so successful in the Moth. Our general theory, then, was to design a hydrofoil that could get to the weather mark soon after a conventional C-Class cat, and then pass them with dramatically improved speed and direction on downwind legs.
The downfall of Rocker was the added wetted surface of many foils under the water and reduced righting moment due to a reduction in beam to meet the C-Class 14’ max beam restriction (for hulls and foils). She flew nicely, was under control, but a few knots slower on average than Alpha.
Alpha, winner of the 2007 International C-Class Catamaran Championship, is constructed from lightweight carbon fibre and carries an adjustable-camber hardsail (wingsail).
The C-Class rules leave ample room for imagination. Make a symmetrical catamaran that fits into a box 25 feet long, 14 feet wide, stick on 300 square feet of sail area and you will be legal. Any kind of sail, any hull shape, any weight, any material. A designer’s dream.
The boat was sailed by project leader/skipper Fred Eaton, and wingman Magnus Clarke. While I was the chief designer, Fred and Magnus both played significant roles on the design team and that improved their understanding of the boat while sailing.
In any race victory there are a host of small factors that combine to produce success. In our opinion, the biggest factors that led to our win in the C-Class Championships were our lower overall weight (the lightest C-Class ever built at 360 lbs. ready to sail), our high aspect ratio, thin foil section hardsail and the crew’s opportunity to spend more time on the water leading up to the event. The latter gave them an edge in boat handling and racecourse tactics, which played a significant part in the result.