Admirals Cup which is an international competition based on teams of three boats, run by the Royal Ocean Racing Club from Cowes

The Admiral's Cup began as a private challenge in 1957, but in 1959 the club was asked to run the series and although the Americans did not return that year, Holland and France took part. The story was then one of continual expansion of the number of teams, which reached a maximum of 19 (57 boats) between 1977 and 1979. After 1985, in terms of the number of three boat teams, there was a decline as the kind of yacht needed to compete both offshore and in additional specified inshore courses (even Olympic or Olympic style layouts), became progressively more unusual and expensive, as did the paid crew.

Commercial sponsorship of the series by a French company, Champagne Mumm, began in 1983, while the first British boat to be sponsored, rather than privately owned, appeared in 1991. The Admiral's Cup had become at its origin almost by accident (because the allotted courses were already in existence) a novel kind of yacht racing which combined inshore and offshore racing. It steadily became a model of its kind, spawning welcome imitators including the Southern Cross (Australia), the Onion Patch (NE USA), Hawaii (Kenwood) Cup, Sardinia Cup, the RORC/IOR Ton Cups and a range of regional and local competitions..

http://www.rorc.org/admiralscup/index.php