Not long ago all America Cup boats were single hulled with a maximum speed of about 15 mph. The winner gets the advantage of setting the specifications for boats for the next America's Cup competition. They have used catamaran's for several years. The catamarans are capable of, get this 45+ mph. They are incredibly expensive.
I have LOVED sailing since I was a teenager, I can't imagine 45 mph on a catamaran. They are so fast now the crews are required to wear helmets and body armor.
The Oracle was down 1 race to 8 for the New Zealand when the owner of the Oracle took the boat out of the water, changed some things, changed the strategist and several others on the crew. They then went out to wind eleven straight races. They were penalized 2 points because of an illegal change in the boat, during warm ups and still won 9-8.