A Vanguard-class submarine returned to Faslane today after 205 days away, breaking the previous record for the longest unbroken patrol by a Royal Navy submarine.
This boat left its base in September 2025 and has been underwater for more than six and a half months. She was relieved in the last few days by another boat that sailed on Sunday. The previous deterrent patrol lasted 203 days, and every one of the last nine patrols has exceeded five months in duration; six months plus is becoming the new ‘normal’. Today’s homecoming marks another demonstration of crew endurance and professionalism in safely operating an exceptionally complex vessel.
On paper, longer patrols are more ‘efficient’ as it reduces the time spent in handovers and there are longer periods to conduct post-patrol maintenance, recover and prepare for the next. However, it also adds additional risk that the continuous nature of the deterrent could be compromised as these ageing boats must avoid serious defects and be stay at sea for longer.
The Prime Minister and other VIPs boarded the submarine on the Clyde to deliver their thanks to the crew (Photo: Michael Cuthbert).
In the last few years, there were instances where a planned 99-day patrol was extended and eventually exceeded 200 days. Since the 6-month patrol has become more ‘routine’, the crew already know they are going to be away and underwater for a very long time. This allows them to mentally prepare as best they can beforehand and set expectations for friends and family.
Knowing the boat will be away for so long also means the boat can be crammed with the enormous volume of stores needed to sustain the crew. The Vanguard class were originally designed with food stores and freezers to support a maximum of 3-4 months at sea. For the first couple of months, stores will be packed into every available space, and the decks in the passageways will be covered with canned food. The amount of toilet rolls alone must be staggering. Some gash can be ejected from the boat, but some of the waste has to be stored on board, crammed into spare compartments.
Provided there are no serious mechanical problems, able to produce its own power, make freshwater, produce oxygen and remove excess CO2, nuclear submarine endurance is theoretically almost indefinite. The limiting factor is the mental endurance of the people on board and their food supply. In the 1980s, submariners manning the Polaris boats thought of anything more than 8 weeks away to be a long patrol and tough on all involved. Most SSN and SSBN operating navies now see anything around 100 days to be a very long patrol and the sensible maximum.
So far, there is no evidence to support this, but there has been speculation that boats might be resupplied midway through the patrol. This would be against the key principle of the nuclear deterrent that must remain submerged and undetected. Resupply would need to be done as discreetly as possible, probably at night and in a partially sheltered location. The vessel involved may have been specially equipped for the task, as coming alongside a submarine in open water is not easy. Alternatively, a helicopter could VERTREP supplies onto the casing.
A submariner recently gave Navy Lookout some insight into what it was like on a very long patrol. He said many aspects of such a unique job are rewarding and enjoyable, but “some people really struggled towards the end, although nobody really cracked up, we helped each other through. Time really seems to slow down in the last couple of months, but it was just a case of keeping in the routine, rinse and repeat every day”. Generally, submariners work in a continuous two-watch system with 6 hours on duty and followed by 6 hours off to rest, eat and sleep, sustaining this pattern of life for the whole patrol.
Families on Rhu Spit welcome them home (Photo Michael Cuthbert).
“When you finally surface, the world initially smells terrible as you have been breathing the purified air in the boat for so long. It takes time to adjust to being home and I felt quite numb when I first saw my girlfriend and my family. The time spent on the patrol was soon forgotten, and it faded quickly, not seeming like six months. You get so used to the noise of the forced ventilation, I found it really hard to sleep at home when there was silence.”
Communication with the outside world is limited to a short email from family once a week that is vetted both ashore and by the CO before being passed on to the recipient to ensure it does not contain anything that might be upsetting. The boat will also download news and sports results to be shared on board when it comes close enough to the surface to receive messages.
Eyesight and distance perception are affected, and it’s not advisable to drive for a few days after a patrol, having not looked at anything more than a few meters away for months.
Even the most junior submariner is likely to return home with a pretty healthy bank balance, having no opportunities to spend money ashore while away. Although this cannot fully compensate for the psychological pressures and separation from the rest of the world, the funds accumulated can really mount up. Rank, qualifications, time served and role-related retention incentives mean the pay scales are complex and vary widely, but submariners are paid more in basic pay than their counterparts in the surface fleet. On top of this, all personnel are paid a daily Longer Separation Allowance (LSA) for each day they are at sea. There is a further bonus paid when patrols are extended beyond a few months.
The marine growth on the hull gives some idea of how long she was underwater, although the growth is not quite as extensive as seen on some returning boats recently (Photo: Micheal Deveney).
There are three main causes for the increased patrol length. In 2010, the Cameron government decided to delay main gate approval to start the Successor (now Dreadnought) programme by five years. This supposedly saved around £750M in the short term, but in the long run, added additional costs that run into £Billions. Even more seriously, it placed the whole submarine force under growing pressure throughout the 2020s and risks the sustainability of the deterrent itself.
The pedestrian pace of construction of the first of the new class of replacement submarines, HMS Dreadnought, does not help. First steel for her was cut in Barrow during 2016, and she probably will not conduct her first patrol before 2032, a whopping 16 years (about double the construction time of HMS Vanguard and four times that of HMS Resolution).
Failure to invest in submarine support infrastructure has also increased the time spent in maintenance or the amount of time waiting for facilities to become available. HMS Victorious is currently in Devonport, undergoing a multi-year Deep Maintenance Period (DMP), which began in May 2023, while a third boat has been in Faslane for over 19 months and not in the recent patrol rotation.
Heading up Gare Loch into Faslane (Photo: Stuart Rich).
Maintaining the UK’s continuous-at-sea deterrent is assuming ever-greater importance at a time of increasing uncertainty about European security. Although CASD remains UK defence priority one, the RN is stretched to uphold this commitment as the boats get older. The arrival of the new Dreadnought class and improvements to submarine infrastructure cannot come quickly enough. Normalising six-month patrols is not something to be celebrated, but the crews deserve recognition for their service and sacrifices, despite frequent tabloid headlines about the misdemeanours of submariners.
Main photo: Michael Cuthbert
