Sailing? Flying?

This is a view of the NZ Boat currently thrashing the USA 6-1 in the America's Cup-despite Sir Ben Ainslie being called in to sail for the US! I've never seen boats like this before, they sometimes 'fly' on the 4 foils-the fins you can see on this hull-and reach speeds of around 50mph! All the racing is taking place in San Francisco Bay so along with exciting races there is great scenery!