Steve Killing (The designer for the Canadian team, I think) wrote a 16 page article which I found somewhere on the net (I`m really good at finding stuff, and really bad at remembering where.)
It was titled "THE 19th CHESAPEAKE SAILING YACHT SYMPOSIUM" - ANNAPOLIS, MARYLAND, MARCH 2009 - ALPHA AND ROCKER - Two design approaches that lead to the successful challenge for the 2007 International C-Class Championship.

It is a fantastic article, detailing almost all the aspects of the design of both boats (They are actually identical - one foiling, one not. They tested them both against eachother and chose the faster boat (non-foiling) to challenge Cogito.
It is amazing how much info he is prepared to share, quoting Naca specs for the foils & daggerboards, Lift/drag charts, Data tracks, construction details, GPS Polars, and more.
Some of his comments :
"Two boats were designed for this challenge - the first
was Alpha, a wingsail catamaran, which incorporated some
new thinking on sail configuration and hull shape. This
made it a successful evolutionary, but not revolutionary,
step from the current state-of-the-art boats. Compared to
Cogito, the main rival, she had a taller, narrower and
thinner wing, lighter construction and more circular hull
cross section. The second was Rocker, the bold hydrofoil
catamaran, using hulls from the same mold as Alpha and an
identical wingsail as the driving force. The daggerboard
hydrofoils automatically controlled the ride height with
trim tabs, while the control of the rudder elevators was left
to the helmsman. Although she flew well, was very
controllable, and was spectacular to watch, Rocker could
not match the 20 knot plus speed of Alpha." and :
"After this fairly careful experiment in foiling, we are
comfortable concluding that hydrofoils don’t perform in
this configuration on a C-Class catamaran. There is no
doubt that fine-tuning our parameters could increase
Rocker’s speed, but it will take more than fine tuning to
make the required leap in performance. We encourage
other teams to learn from our experiments and go forward
to find the solution that will push hydrofoiling catamarans
to the next level of performance."

I hope he doesn`t mind me quoting this here, but if you have a real interest in this I`d suggest trying to find a copy of the full article. I think it may have appeared on Sailing Anarchy or Boatdesign.net, but I seldom remember anything past last week Wednesday.