There’s been some interesting posts on this thread and I think the decision to cancel the Attack class submarine was the correct action in the current political climate - for quite a number of reasons. The key development allowing the RAN to purchase/build SSN’s is the availability of reactors that have sufficient fuel for the life of the vessel. This means that there is no requirement to build the massive infrastructure to handle radioactive material or rely on other nations to refuel the vessels. Even though the new nuclear powered submarines will not be operational for many years, the decision has sent a strong signal that the West will stand united and will not allow expansionist aggression by any country to occur.
A number of people have expressed concern about a potential gap between the Collins class retirement and the future SSN’s becoming operational, but the planned Collins Life of Type Extension (LOTE) should adequately cover that period.
I understand that the fatigue checks on the 6 boats has confirmed that all the hulls are suitable for the LOTE and, if the information on Wikipedia is accurate, these hulls have better steel than even the Virginia class SSN’s.
“ The hull is constructed from a high-tensile micro-alloy steel, developed by Swedish steel manufacturer SSAB, and improved by BHP of Australia, which was lighter and easier to weld than the HY-80 (LA class) or HY-100 (Virginia class) nickel-alloy steel used in contemporary submarine construction projects, while providing better results in explosion bulge testing.”
The first boat (HMAS Farncomb) is to commence the LOTE in 2026 in conjunction with a planned 2 year full-cycle docking. The aim is to try to complete the LOTE within those 2 years but, being the first to go through the process, it is expected to run a little overtime, possibly as long as an additional year. On completion, it will have 10 more years of operational service before its expected retirement circa 2039. The LOTE will involve separation of hull sections to allow replacement of all 3 diesel generator units, the main electric motor with possible replacement of batteries, fitment of telescopic photonic masts & acoustic upgrades. It may also involve sonar upgrades if they haven’t been previously fitted to the vessel.
Subsequent vessels are programmed to follow every two years with the last boat to complete the LOTE, HMAS Rankin, possibly retiring after 2048 so that should allow sufficient time for the first 4 SSN’s built in Australia to be operational.
The Collins class is currently experiencing good availability and all are now fitted with the AN/BYG-1 combat system (same as Virginia & retro-fitted to the LA class) and are thus performing well. They are getting a number of Sonar upgrades, a Modular Cylindrical Array (MCA) based on Sonar Type 2076 submarine technology developed by Thales teams in the UK (as fitted to the Astute class). The existing flank array will be replaced by the latest generation flank array as well as new High Frequency Intercept arrays and the locally developed Heron Mine & Obstacle Avoidance System (MOAS). Thus, in conjunction with LOTE acoustic improvements, they will remain as a full fighting force for the duration of their service life. They currently are armed with Harpoon anti-ship missiles and the upgraded Mark 48 Mod 7 Common Broadband Advanced Sonar System torpedo which was jointly developed by the US and Australian navies. This torpedo’s CBASS guidance control system has wider sonar bandwidth and can function at depths much greater than 365 meters. More resistant to enemy countermeasures, the CBASS torpedo variant can be optimized for targeting fast, deep-diving diving submarines or slow-moving submarines and surface ships in shallow waters.
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If it is decided to purchase/build the Virginia class, the RAN would probably be looking at the Block VI configuration because it will have the acoustic enhancements that are currently being trialled aboard the USS South Dakota. This means the Australian SSN’s will have the latest available technology which is necessary as the RAN traditionally keeps vessels in service for their full fatigue life. They must be upgradable to ensure they are effective and survivable throughout their service life. The US plans to order the Block VI for production in the 2024-28 timeframe so this should fit with the Australian construction timetable. It’s even possible that the later vessels could be built to Block VII standard.
The submarines can be built without the Virginia Payload Module (VPM) at a saving of about US$500M per hull but the VP Tubes add a lot of flexibility & firepower as well as providing a launch capability for future UUV’s & hypersonic weapons. It would future proof evolving capability to include the VPM on at least half of the fleet - to not have VPM capability would limit how much the Virginia’s could be adapted to new technologies through to the end of their service life.
The 33 year life of the Virginia’s S9G reactor (& its much higher output) gives a significant advantage over the 25 year life of the Astute’s PWR2 which is reported to be out of production & has some safety concerns (Fukishima like, primary cooling system). The extra life that the reactor gives the Virginia class helps to offset its higher cost. The US has better facilities for disposal of the reactor core at the end of the SSN’s service life at the US Department of Energy’s Hanford Nuclear Reservation in Washington State. The UK has had all of their older submarines stored at Devonport (Plymouth) & Rosyth for a long time and have finally started the process of removing radioactive components and disassembling them. There have been a number of reports about maintenance events on the Astute class which would indicate that design is not as operationally mature as the Virginia’s.
Another plus for selecting the Virginia would be the higher level of support (maintenance & re-arming) available at US submarine bases in the Pacific & Indian Oceans. If the Astute is selected, the RAN would have to arrange larger infrastructure & logistics.
There are still many hurdles, especially to get US Congressional approval, etc. I believe the leaders in the US would generally be in favour of a long term, trusted alliance partner having access to the latest technology as it assists them in doing the heavy lifting in maintaining peace throughout the Pacific.
PS. There are a lot of articles indicating that the US doesn’t have any spare submarines that the RAN can lease prior to building their own. The number of SSN’s in the US Navy fleet is currently way down on what they need so they can’t spare one. The only possibility is to take one of the Block II Los Angeles class boats that is in the process of decommissioning, paying for a very expensive refuel and overhaul, then try to keep it serviceable for another 10 years while the RAN sailors gain SSN experience. The USS Oklahoma City completed its final voyage in Bremerton a few days ago so it could be a candidate but, following the RAN’s experience with the Kanimbla class rust buckets, I can’t see them going down this path. Also, the USN currently has a backlog of submarines idle while waiting for their turn for refuelling & overhaul because the small number of shipyards able to do this work are unable to meet the demand - they wouldn’t be able to fit another vessel in their timetable for it to be prepared for RAN use.
The hapless USS Boise returned from a patrol in 2015, and it hasn’t gone back on patrol since. Posting crew members to RN & USN submarine positions may be the only way for RAN submariners to learn how to operate SSN’s. The Royal Navy also doesn’t have any spare submarines available for lease.
