Hey Gibbon -- I'm not sure what catamaran you were looking at, but the America's Cup boats are actually even LARGER than that ...
The AC45 (the boat being used in current cup events while the larger AC72's are being designed and built) uses a 21.5m (71ft) wing ... and the boats that will be used in the actual Cup (the AC72) are even larger beasts -- a wing 40m (131ft) tall [1].
The design of and technology going into these AC class boats is fascinating. It's been a lot of fun watching the AC45's race and the AC72's will be quite a sight out on the water once they begin pushing 'em to their limits.
[1] http://www.cupinfo.com/en/americas-cup-2013-boats-ac72-ac45....