Designed by Ben Lexcen (formerly Bob Miller) and built by Stephan Ward for owner Alan Bond, Australia II featured an innovative winged keel design developed by Lexcen with assistance from several Dutch engineers.
The 12-Meter Class yacht Australia II, bearing sail number KA6, represented the Royal Perth Yacht Club in its 1983 challenge for the America's Cup . The defender, the New York Yacht Club, had held the cup since 1851, dominating challengers and sustaining the longest winning streak in sports. Australia II, skippered by John Bertrand faced Dennis Conner sailing the 12-Meter Liberty in the ocean off of Newport, Rhode Island, USA, September, 1983.
Australia II came from behind to prevail 4 races to 3. The victory was a landmark event for the nation of Australia, not to mention the New York Yacht Club.
The winged keel was the most notable design feature of the boat, and helped to make it very fast and manoeuvrable in many conditions. Still, many experts point out that Australia II had a number of significant strengths in addition to the keel. Australia's sail technology in particular had finally equaled or exceeded that of the Americans. Further, Bertrand made sure he and his crew was trained and refined to execute at the highest levels despite the pressure of this historical matchup.
The winged keel was an alarming issue during the summer of 1983 as selection trials took place for the coming Cup defense that fall. It was unclear whether the keel design was legal within the strict rules governing the 12-meter class. Questions also surrounded the genesis of the keel. Australia II under the rules had to be designed by an Australian, but some information led observers to believe the Dutch had been co-creators of the design rather than simply playing the testing and support role allowed. The keel design was eventually confirmed as legal while the keel origin controversy remains unanswered today. The distraction of the keel, heightened by the tactics keeping it hidden from view until competition was over, may have undermined the NYYC's focus on the competition.
Despite being the first 12-Meter to sport the new design, Australia II was not the first boat to have a winged keel. Her success did much to make the concept popular, though.
In the mid-1980s, Australia II was sent to the maritime museum in Sydney, Australia, for display. For the 150th anniversary of the America's Cup, as a one-time event the boat was removed from the museum and shipped to the Isle of Wight in England where she sailed with the original crew for several days of commemorative regattas. The boat has since been returned down under to go on display in its permanent new home in Perth.