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Australia II

WA Maritime Museum - Joy of Museums - Australia II

Australia II (KA 6) is a 12-metre-class America’s Cup challenge racing yacht that won the 1983 America’s Cup for the Royal Perth Yacht Club. She was the first successful Cup challenger, ending a 132-year tenure with 26 successful defences by the New York Yacht Club.

Australia II was designed by Ben Lexcen, and featured a reduced waterline length and a short chord winged keel which gave the boat a significant advantage in manoeuvrability and lower ballast center of gravity. The winged keel was a major design advance, and its legality was questioned by the New York Yacht Club. During the summer of 1983, as selection trials took place for the Cup defence that autumn, the New York Yacht Club challenged the legality of the keel design. The controversy was decided in Australia II’s favour.

Australia II sported a number of other innovative features that contributed to her success, including radical vertical sail designs, all kevlar running rigging and a lightweight carbon fibre boom.

WA Maritime Museum - Joy of Museums - Australia II 2

The winged keel was a major design advance, and the New York Yacht Club challenged the legality of the keel design

The rules of the America’s Cup state that the yacht is to be designed by citizens of the nation it represents. Controversy arose due to cup rules allowing designers to use model basins for testing that are not located in the challenging country. This led to suggestions that the vessel was not designed by Australians. It was eventually established that Lexcen had been experimenting with wing adaptations to the undersurface appendages of boats before, including his 1958 skiffs Taipan and Venom. In 1983 Lexcen commented on the controversy:

“I have in mind to admit it all to the New York Yacht Club that I really owe the secret of the design to a Greek guy who helped me out and was invaluable. He’s been dead for 2,000 years. Bloody Archimedes…”

Essential Facts:

  • Name:                 Australia II (KA 6)
  • Yacht club:         Royal Perth Yacht Club
  • Nation:                Australia
  • Class:                   12-metre
  • Sail no:                KA–6
  • Designer:            Ben Lexcen
  • Builder:              Steve Ward
  • Launched:          1982
  • Skipper:              John Bertrand
  • Victories:            1983 Louis Vuitton Cup; 1983 America’s Cup
  • Displacement:   21.8 tons
  • Length:               13.10 metres (43.0 ft) (LWL)
  • Beam:                  3.64 metres (11.9 ft)
  • Draft:                   2.72 metres (8 ft 11 in)
  • Sail area:            175 square metres (1,880 sq ft)
  • Museum:            WA Maritime Museum


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Photo Credit: By GordonMakryllos (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons