Collins-class

The Collins class was developed to replace the Royal Australian Navy (RAN) Oberon-class submarines. Planning began in 1978 under procurement designation SEA 1114. In 1987, the Australian government selected the Type 471 design from Swedish shipbuilder Kockums, an enlarged version of the Västergötland class. The Australian Submarine Corporation (ASC) constructed six vessels in South Australia between 1990 and 2003.

The vessels are single-hulled diesel-electric submarines with two continuous decks. The hull is constructed from a high-tensile micro-alloy steel and covered in anechoic tiles developed by the Defence Science and Technology Organisation to reduce sonar detection. The propulsion system consists of three Hedemora diesel engines and Jeumont-Schneider generators driving a single skewback propeller. For maneuverability, the boats utilize X-shaped aft control surfaces. Sensors include the Scylla bow sonar array and the SHOR-TAS towed passive array. The original combat system was replaced by the Raytheon AN/BYG-1 system, which is also utilized by the United States Navy Virginia class. The submarines are equipped with search and attack periscopes, with the former scheduled for replacement by optronic masts.

All six vessels—Collins, Farncomb, Waller, Dechaineux, Sheean, and Rankin—are based at HMAS Stirling in Western Australia. Primary missions include patrolling, intelligence gathering, and special forces support. Early service was characterized by technical issues involving the combat system, engine reliability, and hydrodynamic noise. Personnel shortages also limited operational availability during the first two decades of service. In 1999, the class supported the International Force for East Timor (INTERFET). During various multinational exercises, such as RIMPAC and Tandem Thrust, the class conducted simulated engagements with nuclear submarines and aircraft carriers. A safety incident occurred in 2003 when HMAS Dechaineux experienced internal flooding during a deep dive, leading to a reduction in the class's maximum diving depth.

Since 2016, the class has maintained higher availability levels following reforms to sustainment and maintenance cycles. A life-of-type extension program is planned to maintain the fleet until the introduction of nuclear-powered replacements under the AUKUS partnership.