Australia won the the America's Cup for the only time in 1983 with Australia II representing the Royal Perth Yacht Club, owned by Alan Bond.
If you are referring to the Copa America, Australia has never been invited to compete. Technically, however, they could be invited as an "at large" team from another confederation as Japan was in 1999, and will be in 2011.
Australia can not win it as the American cup is played only among American countries.
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