About 15 years ago, the Royal Australian Navy (RAN) ordered what it described as a most advanced conventionally powered submarine—quiet, with a sophisticated sonar and a very advanced combat system.
The new submarines were to be a vital strategic system, patrolling well outside Australian waters, not only providing a deterrent but also collecting intelligence, particularly electronic. The operational requirement was to maintain two units on patrol 2,500 miles from their base at HMAS Stirling in northern Australia, which translated into high availability and an endurance of about 70 days. Lengthy operational endurance in turn translated into a very large submarine of about 3,300 tons. The numbers—six—reflected the U.S. experience that it takes three ships to keep one forward deployed. The Australian Submarine Corporation plant at Adelaide was to handle refits. Although not a conventional shipyard, in that most parts were to be manufactured elsewhere in Australia, it can haul submarines into sheds where their entire hulls are accessible.