Collins-class submarine replacement project

Planning to replace the Royal Australian Navy's (RAN's) Collins-class submarines began in 2007 with the commencement of defence acquisition project SEA 1000. The six Collins-class boats are due to leave service from 2025 onwards, and are to be replaced by a class of twelve submarines.

The project is looking at four options to replace the submarines: buy a Military-Off-The-Shelf (MOTS) design, modify a MOTS design for Australian conditions, design an evolution of an existing submarine, or design a new submarine from scratch. The resulting vessel is tentatively identified displacing around 4,000 tons, will be equipped with land-attack cruise missiles in addition to torpedoes and anti-ship missiles, and need to be capable of performing surveillance and intelligence-gathering operations (both directly and through the delivery and recovery of covert operatives). Nuclear propulsion has been ruled out by the Australian government. Construction will occur at the ASC shipyard in South Australia, although other companies will be invited to tender against ASC to build the submarines. The project is predicted to cost A$36 billion: the largest acquisition undertaken by the Australian Defence Force.

The original plans called for concept work to start in 2009, the establishment of preliminary designs between 2011 and 2013, detailed design work from 2013 to 2016, and construction to start that year. This timeline would have had the new submarines entering service before the Collins' began phasing out. However, the preliminary design phase did not begin until May 2012, and entry-into-service for the first new submarine is optimistically predicted as 2030.

Project history
Built during the 1990s and 2000s, the Collins-class submarines have a predicted operational life of around 30 years, with lead boat HMAS Collins (SSG 73) due to decommission around 2025. The Submarine Institute of Australia released a report in July 2007 arguing that planning for the next generation of Australian submarines had to begin soon. In December 2007, a month after coming into office following the 2007 federal election, Minister for Defence Joel Fitzgibbon announced that planning for the Collins class replacement (designated SEA 1000) had commenced. The SEA 1000 project office was established within the Defence Materiel Organisation in October 2008, and is being jointly administered with Defence's Capability Development Group. In February 2009, Rear Admiral Rowan Moffitt was appointed as project head.

The 2009 Defending Australia in the Asia Pacific Century: Force 2030 white paper confirmed the replacement project, and announced that the submarine fleet would be increased to twelve vessels. Reasons for the increase presented in the white paper included the growing quantity and sophistication of Asian-Pacific naval forces (particularly submarine forces), the need to sustain submarine operations in any conflict, and the greater deterrent an increased submarine force would provide.

Originally, the planned timeline called for concept work to start in 2009, preliminary designs to be established between 2011 and 2013, then detailed design work completed in time for construction to start in 2016. This was to ensure that the new class would be in service before the Collins class began decommissioning in 2025. However, meetings between Moffitt and the National Security Committee to clarify concept details and intended capabilities, scheduled for November 2009, did not go ahead until March 2012. On 3 May 2012, the Australian government announced funding for the initial design phase. The initial phase will encompass studies to select the new submarines' design, Defence Science and Technology Organisation projects to establish parameters for propulsion, combat system, and stealth capabilities, along with initiating programs to develop the required industry skills for the actual construction. Under the revised timeline, the preliminary phase will conclude in 2013, with 'first pass approval' to be done by early 2014, and 'second pass approval' in 2017, after which construction will start.

With the project's early delays, the best case scenario for seeing the first new submarine enter service will be after 2030.

Possible designs and planned capabilities
In the 2009 Defence white paper, the replacement submarine had been outlined as a 4,000-ton vessel fitted with land-attack cruise missiles in addition to torpedoes and anti-ship missiles, capable of launching and recovering covert operatives while submerged, and carrying surveillance and intelligence-gathering equipment. It is likely that the submarines will be fitted with the United States AN/BYG-1 combat system.

There are four possible routes for the SEA 1000 project to take, in order of increasing complexity and risk:
 * Buy a Military-Off-The-Shelf (MOTS) design without modification
 * Buy a MOTS design, but modify it for Australian service conditions
 * Design an evolution of an existing submarine
 * Design an entirely new submarine

Designs considered for the two MOTS routes include the Spanish S-80 class, the French-Spanish designed Scorpène class, the German-designed Type 214, and Japan's Sōryū class. Scaled-up proposals of the S-80 and Scorpène classes, as well as the Type 216 (an enlarged version of the Type 214) have been offered by the respective designs' parent companies as possibilities for modification. An updated version of the Collins class design is also being looked at: the original submarine was designed for the RAN's unique operating environment, and replacing or fixing the issues that affected the original submarines while updating equipment and systems would result in a design that meets the white paper requirements. SEA 1000 will most likely follow the 'modified MOTS' or 'evolution' path. No existing MOTS submarine design meets the RAN's desired capabilities, or would successfully operate in the warm seas and huge transit distances of Australian service. MOTS submarines were initially ruled out by the project in March 2011, but were put back on the table in December 2011. At the other end of the scale, designing a submarine from first principles is considered incredibly risky.

The Australian government has rejected nuclear propulsion. Reasons for the rejection include the lack of a nuclear power industry and the related infrastructure and regulatory guidelines (Australia would be the only non-nuclear nation to operate nuclear submarines), as well as public opposition to nuclear technology. Defence commentators have suggested that the United States Navy's Virginia class nuclear-powered submarines would fit the outline given in the white paper. But instead the recent defense technology deal could see Australia adapt the AIP technology of the Sōryū class submarines.

Even though the Australian government had decided to use diesel power instead of nuclear propulsion for the replacement submarine, the University College London International Energy Policy Institute in Adelaide published a paper on its feasibility on 12 August 2013. The paper argues it is entirely feasible for Australia to replace its submarines with nuclear-powered craft at the same cost of conventional designs. The paper does not directly advocate a nuclear fleet and doesn't address strategic, tactical, or political questions in detail. It is intended to spark debate in Australia about what sort of submarines could be selected. The UCL paper says a nuclear craft fits the requirements of increased range, endurance, and strike capability compared the Collins class, and that a domestic nuclear industry is not needed to obtain a nuclear fleet. Its authors argue that a nuclear sub would have a significant impact on the pacific region by providing a deterrent advantage because they can remain submerged indefinitely, have high speed, and deploy quickly. Nuclear submarine costs are concluded to be competitive, with overall costs at US$1.8 billion to US$2.7 billion. Suppliers of nuclear boats would likely be close allies, with the U.S. having surplus ships, utilizing the military cooperation agreement with Britain, or using France as a source, though with less advanced technology.

Construction
Initially, the Australian government promised that the government-owned ASC, the company responsible for building the Collins class, would build the new submarines. However, it announced in May 2009 that a request for tender would be released for the construction work. The submarines will be built at ASC's shipyard in Osborne, South Australia; if a company other than ASC is the successful tenderer, they will be granted access to the site. Construction is predicted to occur over a 25 year period, with the new submarines operating until the 2070s.

In December 2010, an update to the 2009 Defence Capability Plan forecast the cost of the project as over A$10 billion. However, the Australian Strategic Policy Institute has predicted that the new submarines will cost over A$36 billion to design and build, with construction of each submarine valued between A$1.4 and A$3.04 billion. The Collins replacement project has been identified as the most expensive ever undertaken by the Australian Defence Force.

Instead of building all twelve submarines to the same design, building them in 'batches' is under consideration. Doing so would allow new technologies and improved equipment to be added to the latter submarines through evolving design and research work, but would likely come at an increased cost.