Key Points

• The plan to put all six Collins-class submarines through an extensive and risky life of type extension (LOTE) that could keep some in service well into the 2040s is an artefact of the previous submarine transition plan that aimed to reach a fleet of 12 Attack-class conventional submarines.
• The current transition plan—the ‘optimal pathway’ to a fleet of eight or more nuclear-powered submarines (SSN) combined with AUKUS partners’ SSNs operating from Western Australia has very different drivers and risks. Therefore it will require a different LOTE.
• Due to the extreme competition for uniformed workforce, industrial resources and funding, it is highly unlikely that any Collins will remain in service beyond the late 2030s; the arrival of the third Virginia-class SSN will probably mark the end of the Collins’ service.
• Once we recognise this, the LOTE can be smaller, simpler and less technically risky, involving fewer upgrades and fewer boats. The timing and order of the retirement of Collins boats can also be adjusted.
• A large, complex LOTE may itself be a risk to a successful transition.
• Depending on the Government’s confidence in the achievability of the current transition pathway, a simpler LOTE on a part of the fleet may be sufficient to preserve capability and workforce to support a successful transition.

The Royal Australian Navy has begun (again) a long transition in its submarine capability. This will be a hazardous journey. Capability transitions are difficult and can often create prolonged periods of diminished capability and even capability gaps before the new, superior capability is in service. We had virtually no submarine capability at points during the transition from the Oberon-class submarine to the Collin-class submarine. The current transition in the Australian Army’s battlefield mobility capability from the MRH-90 Taipan to the Blackhawk shows how badly things can go. The transition in the Navy’s surface fleet is already going off the rails, with the first Anzac frigate, HMAS ANZAC being retired eight or more years before its replacement enters service. That failing transition has forced the Government to pursue a new fleet of General Purpose Frigates as desperate last throw of the dice to avoid a yawning capability gap in Australia’s surface fleet.

The current submarine transition from the Collins-class submarines to the future nuclear-powered submarines (SSNs) will be the most complex Australia has ever undertaken. We can say already that it won’t occur as planned. Bent Flyvberg, the world’s authority on megaprojects, has assessed that 99.5% of megaprojects don’t deliver on time, budget and benefit (i.e., capability in the defence context). When we consider the SSN program is a constellation of megaprojects, it’s inevitable it won’t roll out exactly as described in the Government’s ‘optimal pathway’.

Public discussion of capability transitions usually focuses on a small number of things which may be important but lose sight of other things which are equally or more important. For example we obsess about when the first element of the new capability will arrive rather than when we will have an effective capability in service. We focus on the new system rather than understanding how we can keep the old one going long enough to ensure we can transition effectively. The collapse of the MRH-90 fleet and the emerging (literal) cracks in the Anzac frigate fleet remind us how quickly the existing capability can evaporate. We need to understand the whole transition journey and the components of it rather than just looking at couple of key dates. And a key part of that journey is the trajectory of the existing system—in the case of the submarine transition, that’s the Navy’s six-boat Collins-class fleet.

The evolution of the Collins-class LOTE

The need for some kind of Collins-class life-of-type-extension (LOTE) to be part of the transition has been recognised by Defence for over a decade now. In essence, the Collins LOTE was the strategic risk mitigator against a capability gap emerging due to a slip in schedule in the replacement submarine. But what the LOTE needs to be depends on the overall nature of the transition.

Currently each Collins-class submarine undergoes a full-cycle docking (FCD) every ten years. The FCD is a major overhaul that takes two years and ensures that the submarine can serve a further ten years. The fleet is undergoing its second round of FCDs. The fifth boat is nearly complete and the sixth will start this year and be completed in 2026. At that point, the first boat, HMAS Farncomb, would need to be retired, with subsequent boats following on a two-yearly cycle that would see all Collins gone by 2038.

It’s been apparent for over a decade that the first replacement submarine would not be delivered until well after 2026, hence some kind of LOTE would be needed to enable each Collins to bridge the gap to the delivery of its replacement. When Defence was pursuing conventional submarines to replace the Collins, the scale of the LOTE steadily grew. Initially Defence indicated it could need to put two or three Collins through a LOTE, but as the delivery schedule for the replacement submarines slipped into the future, the number of Collins that needed to undergo the LOTE grew. Eventually, when Defence was pursuing the Attack-class as the replacement, it acknowledged all six Collins boats would need to go through the LOTE.

Also, when Defence was pursuing a fleet of 12 conventional submarines, one of the key drivers in the transition was to increase the total number of submarines in the fleet. Initially, putting more Collins through the LOTE offered the prospect of increasing total submarine numbers as Collins could potentially serve alongside the new boats as they entered service, but again, as the timetable for replacement slid, it became clear that even putting all six Collins through the LOTE would only barely bridge the gap to the Attack class and do nothing to increase submarine numbers.

The scope also grew, since Collins would need to serve longer in an increasingly dangerous threat environment. The LOTE became more than just an assurance activity to keep them going for another ten years, but a significant capability upgrade (in addition to the program of separate capability upgrades that the Collins fleet has been going through for many years). The scope came to include three of the five major systems on the boats: diesel generators, main motors, and electrical distribution systems. At times other upgrades have been considered for the LOTE including replacing the periscope with digital optronic systems. Indeed, the LOTE was so ambitious that Defence officials publicly claimed that it would result in the Collins remaining ‘regionally superior’ until 2035.

Nevertheless, many commentators have noted that the scope of the program presented considerable risk. While Defence had earlier argued that pursuing a ‘Son of Collins’, i.e., an evolved version of the Collins, to replace the original Collins presented too much cost and risk in return for the capability, the LOTE was itself looking like a Son of Collins. Moreover, if the technical risk grew, the time needed to conduct the LOTE could blow out the two-year FCD window, keeping boats out of the water and decreasing overall submarine availability rather than improving it. There are many precedents for this occurring in extensive upgrades to ageing platforms, such as Australia’s Adelaide-class FFG upgrade program.

In forums such as Senate estimates, Defence officials acknowledged that the LOTE was high risk, but expressed confidence that it could be done for each boat within a two-year window. Indeed, it was also suggested that replacing the major systems would present lower risk than refurbishing them as was normally done in an FCD. Observers expressed some scepticism considering even minor design changes could flow through the boat requiring major modification to compensate for changes in the size and weight of the new systems. It’s not surprising to anyone who has been following this issue that an external review of the LOTE commissioned by the government recently confirmed that it is high risk, according to media reporting.

Defence also justified the ‘big scope’ LOTE by arguing that the new systems going into the Collins would have significant commonality with the Attack class (such as the new main motor), or indeed even be identical (such as the diesel generators). This, it was argued, would mean the Collins LOTE would not only deliver a capability ‘bridge’ but it mitigated the risks around the introduction of new technologies on the Attack class and serve as a training and sustainment bridge as Defence developed understanding of the systems coming with the Attack class before it arrived. Plus, common systems would also deliver economies of scale.

That’s where we got to before the AUKUS announcement. However, it’s important to consider whether the scale and scope of the Collins LOTE should remain the same in Australia’s new submarine transition. The goal of the journey has changed, so the steps on the pathway will likely need to change too. Deputy Prime Minister (and Defence Minister) Richard Marles has recently stated that the LOTE is still necessary to ensure a transition with no capability gap. But what should the LOTE now look like? Is a ‘big scope’ LOTE still needed? And how many boats should go through it?

There’s two ways of looking at this. The first is the demand side perspective, that is, what kind of LOTE is still needed. The second is the supply side perspective, namely what kind of LOTE Australia has the resources to deliver in light of competition for human, industrial and financial resources in the submarine sector. We’ll talk through these issues.

Our planned SSN journey

We’ll start by seeing what we can learn by mapping out at a high level the submarine transition, from where we are now, to the point at which we’ll have the Government’s target of at least eight SSNs in service. This discussion presents the Government’s ‘optimal pathway’ and relies on information the Government itself has made public. It is mapped out in Figure 2 below.

That plan assumes Australia will receive 3-5 Virginia-class submarines with the first transferred from the US Navy around 2032, the second around 2035 and the third around 2038. The fourth and fifth Virginias seem to be ‘fallback’ boats should production of the SSN AUKUS be delayed, so we won’t include them here.

The Government has also said that the first Australian SSN AUKUS will be built in Australia (on a schedule a few years behind the United Kingdom’s own production line) with the first one to be delivered in the early 2040s. Subsequent boats will be delivered on a three-year drumbeat, which is what the UK has achieved for its Astute-class SSNs, broadly speaking.

We can see that the fifth SSN AUKUS (and eighth SSN overall) will be delivered around 2054. At that point, the first Virginia will need to be replaced since it will likely be a second-hand boat that will already have a decade or more of USN service on the clock followed by over 20 years of RAN service. We won’t extend the table, but simply assume that domestic production will continue, producing SSN AUKUS boats to replace the Virginias.

Part of the current pathway also involves establishing Submarine Rotational Force—West (SRF-W). Starting in 2027 USN and Royal Navy submarines will conduct extended rotations through HMAS Stirling in Western Australia, building up to four USN boats and one Royal Navy boat (again, let’s put aside doubts here about whether that British boat will show up).

But as we noted above, we also need to understand what is going on with the existing capability. HMAS Rankin is scheduled to be the last boat through the current FCD cycle, entering its docking this year and completing it in 2026, giving it a further ten years’ life, allowing it to serve until 2036. However, the first boat through, HMAS Farncomb’s, ten years also expire in 2026 and if no remediation is taken, it will retire followed by subsequent boats at two-yearly intervals (that is illustrated in Figure 3). Under that transition we get down to two Collins by the time the first Virginia arrives and none around the time the second arrives.

The first LOTE is scheduled to commence in 2026, seamlessly following on from the last of the full-cycle dockings. If we assume that Defence’s current plan for the LOTE remains the same as when it was transitioning to the Attack class and all six boats go through the LOTE, the first Collins would leave service in 2038 and the final Collins would serve until around 2048 and retire at the ripe old age of 45, as depicted in Figure 2.

But is that still the plan now the transition pathway and destination has fundamentally changed? There’s good reason to question whether that still makes sense under the current pathway for both supply and demand reasons. Not only has the pathway changed, but the drivers for the transition have changed. Under the old pathway (and indeed since the 2009 White Paper), the goal was to increase submarine numbers and get to 12 conventional boats. Under the current pathway, the goal is not submarine numbers per se. Rather, Vice Admiral Jonathon Mead, Director-General of the Australian Submarine Agency has stated the goal is to transition to a nuclear-powered submarine force as soon as possible. If that’s the key driver, keeping many Collins in service is not necessarily a priority, especially if they compete for scarce resources with the nuclear enterprise.

The Government and Defence have not publicly stated what the scale and scope of the LOTE still is, other than the Deputy Prime Minister confirming it is still necessary. However, it does appear that Defence is still planning a large LOTE program. It informed the Senate in January 2023 that, ‘The life-of-type extension program will carry the Collins class submarines through the 2030s and well into the 2040s with a manageable level of risk.’

The Australian Submarine Agency’s October 2023 Senate estimates brief that was released under a Freedom of Information request states that (p. 125), ‘The Life of Type Extension continues on our Collins class submarines, ensuring operational capability is available into the 2040s.’ But it also had the rather vague statement that (p. 145) that ‘The Collins class submarine is a potent submarine capability and will remain so for more than a decade as we transition to nuclear-powered submarines.’ That only suggests some unspecified time after 2033.

The supply side: Industrial capacity

There are two factors that will limit the supply side of the Collins LOTE, i.e., Defence’s ability to keep the Collins going into the 2040s. The first is competition for industrial capacity. Between now and the 2040s, the following 10 industrial activities to support submarines will need to occur to transition along the planned SSN pathway. Many will need to occur concurrently.

• Collins ‘in-water’ sustainment, or operational maintenance. These are the activities conducted at HMAS Stirling in Western Australia that keep boats operational but don’t involve taking them out of the water.
• Collins mid-cycle dockings. These are conducted between full-cycle dockings at Henderson in Western Australia and involve taking the boat out of the water for a year. Currently a workforce of around 600 people is involved in mid-cycle dockings.
• Collins LOTE. As discussed, these will take at least two years to conduct. They will be performed at Osborne in Adelaide. The FCD current workforce is around 1,000 people, but we should remember that the current scope of the LOTE is much more extensive than a regular FCD, requiring more working hours. If it is to be performed in the same time window, it will require more workers.
• SRF-West operational maintenance. The SSN enterprise has already started developing the workforce and infrastructure needed to support US Navy and Royal Navy SSNs that will rotate through HMAS Stirling. According to Richard Marles, 500 people will be required for this.
• RAN Virginia-class sustainment. This will be required from 2032 at HMAS Stirling. Presumably, it will be a similar activity to the support for the SRF-West’s USN Virginia-class boats. Incidentally, it’s not clear in what form the SRF-West will continue once Australia’s own SSN capability is established. The US is seeking to disperse its forces across the Indo-Pacific so it’s likely that SRF-W boats will continue to operate out of HMAS Stirling along with RAN SSNs indefinitely.
• RAN Virginia-class deep maintenance/overhaul. These activities will be a demanding task and will draw heavily on Australian workforce. I previously estimated that deep overhaul activities for Virginias (known as extended docking selected restricted availabilities) require around three times as much work as Collins full-cycle dockings. It’s highly likely that RAN boats’ overhauls will need to be conducted here since there USN is facing a massive backlog of deep maintenance work on its submarines at US shipyards.
• SSN AUKUS construction. Construction is meant to start from the early 2030s at Henderson in Adelaide. The Government has indicated that there will a requirement for 5,000 workers in the shipyard, plus many additional workers in the supply chain. This is likely to be in direction competition with the LOTE for workforce, should they still be occurring.
• SSN AUKUS operational maintenance. This will be required from the early 2040s when the first Australian SSN-AUKUS is scheduled to come off the Osborne production line and enter service.
• SSN AUKUS overhaul. Ultimately Australian will need to be able to perform the deep maintenance and overhaul activities that require the boat to be put in dry dock. There’s no public information on when this will need to start in Australia. But a basic principle is that construction and overhaul activities are very distinct activities that require specialised facilities, workforce and skills.
• East coast submarine base. The current pathway involves establishing an SSN base on the East Coast. This will require duplicating some maintenance capabilities on the East Coast.

We can see that there will be at least ten different lines of industrial effort relating to submarines over the course of the transition. With an industrial base and workforce the size of Australia’s, Defence will need to minimise the number of these that are conducted simultaneously, competing for workforce, resources and dollars. Even if some activities are not conducting simultaneously, the ASA will need to transition workforce between them with as little disruption as possible.

Something is going to have drop off this list. And if the goal is to go nuclear as soon as possible, that something will likely be part of the Collins enterprise.

The supply side: Uniformed workforce

Another area where Defence will suffer from critical shortages is in the uniformed workforce operating the boats.

The Collins has a crew of 56. Navy generally manages to have five Collins crews available, which is around 280 people. But since the total number of qualified submariners needed to maintain a sustainable workforce is around three times the number actually on boats, Navy has around 800-900 submariners—and some experts have stated even that is insufficient to provide a robust force.

The Australian government and Defence Department haven’t said how many submariners will be needed for the SSN fleet, however a senior US official, Dan Packer, the director of naval submarine forces for AUKUS, has stated that ‘Right now, the Australian submarine force is about 800 people. We’re going to build it to 3,000.’ That’s essentially a quadrupling of the workforce. That’s understandable when a Virginia-class SSN has a crew of 135, equivalent to two-and-a-half Collins.

But the real challenge is not the final number per se, it’s how the Navy ramps up to that while still managing to operate Collins. A simplified view of the ramp up looks something like Figure 1—it converts transition pathway in Figure 2 into uniformed workforce numbers. It’s a simplified schematic that simply multiples boats by crew size so it only gives the number of crew in boats; the total number of submariners required will be indicatively three or more times as many. Nevertheless, it shows how steeply the requirement grows through the 2030s—if we assume all Collins go through a LOTE and remain in service as long as possible.

Figure 1: Indicative ramp up of RAN submarine crew requirements

There are of course arguments that considering history there’s very little chance that Australia can support 3,000 submariners. While those claims are not implausible, for the purposes of this exercise we’ll assume here that that reaching that goal is possible—the issue is how we get there.

Defence and its AUKUS partners are, of course, not waiting until the first Virginia arrives to develop nuclear-qualified submariners. The Navy is already starting to train and qualify SSN submariners in the US and UK. Mr Packer stated that 104 Australians would be ‘ingested’ into the US training pipeline every year. Moreover, he added that number will grow every year.

That’s a problem for Collins. Currently Australia qualifies significantly less than 104 submariners each year, probably around 60-80. But they are needed to keep operating the Collins capability. So not only does Australian need to find 60-80 new Collins crew to feed into the Collins pipeline but also 104 candidates for the SSN pipeline, most of whom will likely already be qualified Collins submariners. Essentially it needs to more than double the number of submariners it is producing right now, not some time off in the 2030s.

Since it is highly unlikely it will be able to do that, the Navy faces an immediate prioritisation decision and it will have to take large numbers of submariners off the Collins without replacement and send them to SSN school. So the impact will be felt by the Collins fleet immediately.

Those SSN qualified submariners won’t be coming back to the Collins to wait until Australia gets its own SSNs; they will need to be posted to SSNs to retain and develop their SSN skills. Mr Packer stated that they will be assigned to USN submarines, with 440 Australians ultimately serving on 25 USN submarines. It’s a huge number if he means 440 all at the same time. That’s 440 submariners who are not available for Collins.

The pressure will become acute when the first Virginia arrives. Each Virginia requires the equivalent of two-and-a-half Collins crews. Currently the Navy has five Collins crews, so with the arrival of the second Virginia, our tiny SSN fleet will require as many crew as the Collins fleet currently has. The pressure to cannibalise whatever Collins workforce is left (if any by that point) will inexorably grow as further SSNs arrive. As with industrial capacity, it’s virtually inevitable that something will have to give.

With the pressure on workforce and competition for resources between different submarine classes, Defence will need to reconsider whether it’s worth eking every last year of service out of the Collins. The temptation to retire Collins boats will grow once the first Virginias are in service, particularly with the safety net of SRF-West boats operating out of HMAS Stirling. Facing huge people pressures, it’s hard to imagine Defence will prioritise continuing to operate conventional boats that are approaching 40 years old over SSNs. The arrival of the third Virginia towards the end of the 2030s will likely mark the end of Collins’ service, if it hasn’t happened already.

The demand side of the equation

Considering the supply side pressure, it’s inevitable that Defence will be forced to retire the Collins capability well before 2048. Moreover, with the previous government justifying its decision to cancel the Attack class and pursue SSNs on advice from Defence that the Attack class submarine would be obsolete virtually the moment it was launched, it’s hard to see Collins class submarines remaining a viable front-line capability, even with the benefit of a comprehensive LOTE.

Once we accept that the Collins fleet will retire in the second half of the 2030s, the requirements for the LOTE look very different. And once we move away from a transition model that requires putting all Collins through an extensive LOTE, many possibilities open up around its scope, the number of boats that go through it, the scheduling, and the timing and order in which the Collins fleet is retired.

If no LOTEs or further FCDs are conducted, the last Collins will only just reach the arrival of the second Virginia. And total submarine numbers will fall as low as two (see Figure 3 below)— making it very difficult for Australia to sustain a submarine capability, even if 440 Australians are serving on US submarines. So something will be required, but it won’t be the same as the LOTE that was being planned as part of the transition to the Attack class.

Key assumptions will need to be revisited. For example, does each boat need to serve for a further 10 years after received a LOTE? If a boat remains in service for a shorter period, the scope of the LOTE could be reduced. Does it make sense to replace the main motors and diesel generators if the boats are going to serve for only five years (noting that the replacement motors and diesel generators for at least the first LOTE have been ordered already)? The scope of the LOTE could be more akin to a FCD or indeed the shorter mid-cycle docking.

Alternatively, a smaller number of boats could be put through the LOTE. If we accept that assumption, then the order in which the boats go through the LOTE and/or are retired could change. It’s possible that the oldest boats could be retired when due for the LOTE. Since that would likely create a gap in workflow between the last FCD and the first LOTE, another alternative could put the oldest boats through some form of LOTE, and simply retire the younger boats in the 2030s (that hybrid option is presented in Figure 4 below).

There are of course many moving pieces and uncertainties in this puzzle. Does it represent value for money to do the design work for an extensive LOTE that only a small number of boats undergo? Will there even be the industrial workforce left in Adelaide to perform LOTEs in the 2030s once construction of SSN-AUKUS begins?

Understanding and addressing risk

The problem, of course, is that we don’t know how delivery of the SSN program will pan out. As noted above, we can be certain it won’t be delivered as planned. Unfortunately, it seems to have become unpatriotic and even downright un-Australian to express concern about the risk in the SSN enterprise. Nevertheless, Defence’s submarine planners need to have a clear understanding of the risks in the transition.

Based on the analysis here, if Defence was absolutely confident in the current pathway’s schedule, then a LOTE would be unnecessary. The combination of some work along the lines of a standard docking to provide the assurance some Collins could serve for a few more years, combined with the reassuring presence of SRF-W, would serve to get us through to the point in the second half of the 2030s when the Collins was both unviable and unnecessary.

But it would be irresponsible to turn off the LOTE now, since we can’t know how introduction of our SSN capability will be progressing. Richard Marles’ statement that the LOTE is absolutely necessary indicates that the government and Defence are not 100% confident in the achievability of the transition plan—which is to some degree reassuring.

We can’t predict the future with certainty, particularly in an enterprise that has so many different interdependent variables as the AUKUS SSN pathway. Despite the commitment of the three AUKUS governments to the enterprise, there are risks around the ability of the US to supply Australia with SSNs as planned. There are also risks around Australia’s ability to set up the systems needed to demonstrate it is a responsible custodian of SSN technology.

Whether those risks are resolved or realised will only be known in the future. The final recommendation from the US president to Congress to transfer submarines may not be made until 2030—four years after the first LOTE is due to commence. And it may take longer for the US to develop sufficient submarine inventory for the president to be confident in transferring some. If there are delays in the standing up of the support systems, the president’s decision to transfer SSNs may slide further in the 2030s. Then it will be several years after that decision that we actually get the first boat and then several years after that Defence will know whether the successful operation of SSN’s has taken root in Australia. Moreover, three or four boats are needed to provide a viable capability and we won’t have that until the early 2040s, all going well. Put another way, we could reach the late 2030s or 2040s before we know whether the SSN transition is working. However, the scope of the LOTE needs to be nailed down today so that work can start in two years’ time.

Noting the risks around the transition, designing a ‘big scope’ LOTE would be warranted. We could adjust the scale, i.e., the number of boats, as we go through time, and if we don’t need to do all six, we can simply accept the initial design cost won’t be fully amortised across six submarines. That sounds sensible. But a large scope LOTE gets us back to the risk noted above, namely the technically difficulties may blow out, keeping boats in the shed rather than in service and sucking up industrial resources that could be better employed elsewhere. Moreover, as we’ve discussed there will be major challenges around keeping the Collins in service even after they’ve undergone a successful LOTE. It’s competing for resources with its successor, particularly for uniformed workforce that the SSN enterprise will start to cannibalise from this point on. We could be performing LOTEs to keep Collins boats in service that the Navy simply can’t crew or maintain.

We have then the paradox that while the LOTE has been the strategic risk mitigator in the submarine transition, it has itself many serious risks and as such is itself a risk to a successful submarine transition. The lack of clear statements from the Government and Defence about the current scope of the LOTE suggests that they too are grappling with this paradox.

Ultimately, the more confident the Government and Defence are in their SSN schedule, the less of a LOTE will be needed, both in scope and scale. Unfortunately, once we start retiring Collins boats, it will be difficult if not impossible to quickly return them to service should that confidence be misplaced.

That means the strategic risk mitigator for the submarine transition will now need to come from outside the submarine space. That is, Defence will need to pursue a Plan B, or several Plan Bs. These are not Plan Bs in the sense of capabilities we should pursue instead of SSNs but rather capabilities we need to pursue as well as SSNs. Doing this is not an unpatriotic admission the SSN transition will not work. Rather it takes the pressure off the transition by developing capabilities that can also deliver many of the effects we seek from our submarine force, in particular ‘impactful projection’. This can allow the government and Defence to make rational decisions about where to assign submarine sector resources rather than react desperately to the bad news that will inevitably arise during the submarine transition.

Discussion of what these concurrent Plan Bs is fodder for other posts. Suffice it to say that it should not be more of the same; over the decade SSNs ($53-63 billion), Collins ($4-5 billion in the LOTE plus $8+billion in sustainment), Hunter-class frigates ($22-32 billion) and General Purpose Frigates ($7-11 billion) will already consume a huge proportion of our scarce resources. And considering Defence’s dismal recent record in planning and executing all the activities needed to assure Australia’s naval capabilities, it’s like three of that four may not deliver much real world capability this decade. It’s time to try something different.

Figure 2: The current submarine transition plan – ‘Optimal pathway’ plus full Collins fleet LOTE

Key to Figure: Collins current service is yellow, Collins LOTE is blue, SSNs are green and SRF West subs are orange.

Table is based on public information around the schedule for the ‘optimal pathway’.

Dates next to Collins’ names are commissioning dates. ‘Age’ is age at decommissioning should they go through a LOTE and serve a further 10 years.

Figure 3: The submarine transition plan with no Collins LOTE

Figure 4: A hybrid submarine transition plan – ‘Optimal pathway’ plus partial Collins fleet LOTE