Built from high grade steel – flushed rivet plating, RANGER was launched on 11th May 1937. Having nearly lost the 1934 America's Cup race to the Royal Yacht Club, Harold Vanderbilt took special pains to build a faster boat next time around. She was the Ranger, and dominated the 1937 Cup Season. The Ranger was designed by Sterling Burgess together with the Stephens brothers, who later became famous for their many S&S yacht designs. A typical J-yacht crew included some 26 professionals. The Ranger was all about racing, huge white sails, a flush deck with hardly any built structures, and beautiful lines. Vanderbilt personally financed the whole project, estimated at the time at over half a millon dollars.

Designed by Ben Lexcen, built by Stephan Ward, owned by Alan Bond and helmed by John Bertrand, the Australia II featured an innovative winged keel design developed by Lexcen. This helped to make it very fast and maneuverable in many conditions and was the most notable and controversial design feature of the boat. During the summer of 1983, as selection trials took place for the Cup defense that autumn, it was unclear whether the keel design was legal within the strict rules governing the 12-meter class.

Questions also surrounded the Dutch involvement in the design of the keel, which under the rules had to be designed by an Australian. The keel design was eventually confirmed as legal while the keel origin controversy remains unanswered. Despite being the first 12-meter to sport the new design, Australia II was not the first boat to have a winged keel, though her success did much to make the concept popular.