Can the Royal Navy keep its overstretched Submarine Service cycle going?
The Prime Minister, Sir Keir Starmer, visited the Royal Navy ballistic missile submarine HMS Vanguard on her return from a 204-day long deterrent patrol.
Following this, Sir Keir then laid the keel for the next generation of submarine, HMS Dreadnought, due to enter service in the early 2030s.
This marks an ongoing commitment to the Royal Navy providing a continuous at-sea nuclear deterrent, in a constant patrol cycle that hasn't been broken since 1968.
The question though is whether the Royal Navy can keep this cycle going in the years to come.
The Royal Navy has four Vanguard-class SSBNs in service. All four entered service between 1993 and 1999, and there has been a Vanguard class on patrol continuously since 1996.
They carry up to 16 Trident missiles, capable in theory of carrying up to 192 nuclear warheads, although in reality it is likely to be closer to 48.
When these submarines entered service, the planning assumption was that they would carry out three-month patrols and of the four submarines, one would be on patrol, one would be preparing for patrol and the remaining two would be just back from patrol, undergoing maintenance or in longer-term refit.
In recent years though things have got more difficult to sustain this patrol cycle.
Although the UK committed in 2006 to renewing Trident, the decision in the early 2010s to delay ordering replacement submarines to save money meant that the Vanguard class have had to carry on far past their initial 25-year planned life span.
It is likely that most of the hulls will be approaching their 35th to 40th birthdays by the time they are finally replaced. In warship terms, this is positively ancient.
This extension in service means that the submarines all require additional major refits, which is undertaken in Plymouth.
The first refit, for HMS Vanguard, overran by several years, in part due to her poor material state, as well as challenges caused by Covid.
This meant the other submarines had to work harder to cover the gap caused by Vanguard being stuck in refit.
HMS Victorious finally commenced her refit in 2024, at a cost of some £560m.
At the same time, problems with the wider nuclear submarine shore support facilities, such as the massive dry dock ship lift in Faslane being temporarily closed, have made maintaining and repairing these huge vessels much harder.
The result is that the UK has had to stretch out patrol lengths far longer than any other SSBN operator has to ensure that a submarine is always on patrol.
The reason not breaking the patrol cycle is so important is because it sends a message to a potential aggressor that there are no opportunities for them to ever carry out a sneak attack and wipe out all the UK's SSBNs in port.
There will always be a submarine on patrol able to retaliate if required. If patrols are paused, even temporarily, it provides a potential window of vulnerability for both the UK and more widely Nato, to whom British nuclear weapons are usually assigned as part of wider alliance nuclear plans.
The challenge with six-month patrols though is that they place an incredible ask on the crews carrying out this task.
Few people appreciate the strains of being on patrol in an SSBN.
Once the boat has submerged, she will not surface again for six months, none of the crew will see daylight or smell fresh air.
They will spend the entire time hundreds of feet somewhere below the North Atlantic, as far away from human attention as possible to avoid detection.
The submarine will not send a single external message during this entire time, not one email or signal will be transmitted from her location to avoid it being intercepted by enemy forces.
For the crews, this means six months without any access to the outside world – no internet, no emailing family, no phone calls and none of the small comforts of home life.
To all intents and purposes, they have vanished off the face of the earth, almost as if they were flying on a spaceship to another planet.
The physical impacts on submariners are enormous, deprived of fresh air, proper exercise, sunlight, unable to see more than a few metres in any direction, and living in a confined pressure hull, where most of the 130-plus crew cannot walk more than a few metres in any direction (the nuclear propulsion areas usually remain off limits for non-engineering crew members).
Add this to the punishing watch routine where people will work six hours on, six hours off, in which they need to eat, exercise, do personal admin and sleep in those six hours, meaning they will have spent six months solid not having had more than about four hours of consecutive sleep.
This is a deeply challenging environment to work in, the medical impact on submariners is intense and the long-term health impacts of patrols of this length are not yet fully understood.
In the meantime, the Royal Navy needs to plug the gaps caused by unplanned departures, moving submariners around between submarines to ensure they can sail, but in turn, damaging other people's careers and family lives to meet the needs of the service, will cause more disruption, and in turn more unplanned resignations.
It creates a vicious cycle that cannot easily be fixed.
The Royal Navy is aware of the risks this approach poses and is trying to find ways to retain submariners.
This includes significant pay and allowances, as well as other benefits like deterrent patrols counting towards the earning criteria for the Wider Service Medal.
This will help, particularly for new entry submariners, but for longer serving members, the extra money will potentially be far less appealing than time spent at home with partners and families.
While service life is about sacrifice at times, when this becomes the norm, it becomes far harder to justify missing time away from home, particularly when it isn’t possible to contact families in the way that other sailors can.
In the medium term recruitment may become harder as the RN tries to attract a generation of new sailors who have grown up with smartphones and constant internet access – asking a 20-year-old to take on a job which removes them from their entire social network for six months at a time is likely to prove a very hard sell indeed.
Unless the fleet can urgently regenerate the submarine patrol cycle, dropping it to three months again, and maintain stability in the number of submariners, to help reduce the patrol burden, the real risk is that while maintaining the deterrent will be physically possible, the Royal Navy will lack the people to sustain deterrence patrols on any medium to long-term basis.
This problem will get even more challenging as HMS Dreadnought approaches entry to service when it will need to balance off keeping the elderly and, by then, very frail Vanguard class on patrol, while also bringing an entirely new and incredibly complex submarine class into service.
This will place huge pressure on a relatively small number of people, who are critical to the security of the nation, as if they were to resign in large numbers, owing to the challenges of service life, the ability of the Royal Navy to mount deterrence patrols could collapse.
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