Why The Royal Navy Does Not Need New ASW Corvettes

Is the answer to the Royal Navy’s challenges more, less capable, ships, or fewer but more capable ships? A simple question but one that has been at the centre of naval policy making agenda for decades now.

At its heart is the difficult question about whether the Royal Navy is best placed to meet the many global operational challenges it faces by investing in a small but highly capable force of escort ships, able to operate in every threat environment against peer competitors, or whether it invests more in a larger force of less capable platforms which increase its presence around the world.

Underpinning this argument is a sense by many commentators that what the Navy needs is more ships, and that the only way to get this is to invest in buying lots of smaller ships now to improve overall levels of capability.

Image by Ministry of Defence; © Crown copyright

This argument was recently made in an article by respected defence commentator Nicholas Drummond, who argued that what was required was a force of cheaper corvette style vessels. Perhaps up to 20 would be a highly effective way of providing basic ASW defence and also increasing hulls for operations around the world. Drawing his inspiration from the WW2 ‘FLOWER’ class, he notes that the RN was able to quickly build ships that provided a basic level of defence in an all out general war.

It is tempting to see this as a strong argument for the Royal Navy – build lots of little ships, individually cheap, but which when brought together provide a level of coherent defensive capability against threats that would potentially deter a submarine captain.

The problem though is that ASW today is a very different beast from WW2 and the early Cold War. During WW2 the submarine was effectively a surface ship which could submerge for short periods of time to conduct an attack. In the Battle of the Atlantic German vessels would often attack on the surface, particularly at night, or would only be operationally effective for short periods of time when submerged.

In those circumstances the FLOWER class was an effective deterrent – with limited surface battery and speed, it could easily keep up with the German submarines, and project sufficient firepower to engage them as equals. It could force a submarine to the surface after a long hunt when the need to recharge batteries became too great, and it could present a credible threat to the German forces. As the war developed and larger numbers of ships and aircraft came on stream with more capability, the RN, RCN and USN were able to  effectively hunt and destroy these forces with relative ease.

Today though the threat is utterly different – a credibly handled submarine will not need to surface to attack, and it possesses longer endurance, longer ranged weapon systems and better means of identifying its pursuers. Modern submarines are also significantly quieter than their predecessors, making detection difficult and the certainty of getting a kill limited.

The Falklands War, the last time an ASW campaign was conducted, highlights how difficult it was, almost 40 years ago, to conduct a campaign against relatively modern submarines (and in turn how hard it was for modern conventional submarines to operate against an effective opponent).

The modern nuclear submarine is an enormously capable weapon system and utterly removed from the one of WW2. The problem is that in the popular imagination some people still assume that future ASW is going to be about large convoys sailing through the Atlantic Ocean, with enemy submarines getting close enough to attack and in turn be deterred by small escort vessels.

There are arguably two types of ASW threats out there today. The littoral threat, primarily from SSKs in coastal waters or confined areas – for example in the Med. The other threat is the so-called ‘deep water’ battle, primarily in the deep ocean involving hunting nuclear submarines.  The former is something that many navies may worry about – handling a single SSK near their waters. The latter threat is the most complex in its nature and is the one that the UK needs to be able to fight if it wishes to remain a blue water navy and SSBN operator. 

The reality is that modern ASW is not something that can be done cheaply or via a simple platform. A credible and effective ASW frigate requires three key assets, firstly the sonar processing power to identify, track and prosecute an attack against an extremely quiet target that does not want to be found. Secondly, it needs the means to deliver this attack as far away from the escort ship as possible – which calls for a platform capable of operating a long range helicopter capable of prosecuting an attack. Finally to prevent detection and attack, the frigate is required to be as quiet as possible to avoid notifying submarines of its presence – this requires extensive silencing and mounting of machinery to prevent it giving away a ships presence.

In turn these three characteristics raise the cost of the platform. Modern sonar equipment is incredibly expensive – particularly if you want to opt for things like Towed Array Sonars. If you want it to be able to work effectively against a highly capable target, you need to be prepared to spend a lot of money on it. There may be plenty of ‘cheap’ ASW frigate designs out there, but they almost certainly skimp on the complex underpinning sonar and software architecture required to be effective – and they are not intended to go up against peer threats like the latest Russian SSNs.

In the same vein while some of the designs on the market may have a flight deck or hangar for a small aircraft, what they are not cleared for is operating large Merlin scale helicopters. These are an essential part of the ASW battle – intended to travel quickly to successfully prosecute any contacts, the Merlin is at the heart of the modern Royal Navy frigates ASW weaponry.

The problem though is Merlin is a very big helicopter – when you stand alongside one you realise it is, literally, as tall as a house. This immediately imposes constraints on the design of the ship you want to operate it from – the hangar and support facilities need to be big enough to maintain it. Additionally, to make full use of the phenomenal capability  of the Merlin, you need to have invested fully in the sensors and systems required to make it effective. A failure to do so means the value and utility of the helicopter and the ships is massively reduced.

The two problems here are firstly there simply aren’t enough Merlins in the Fleet to spare for use on a Corvette style platform. The Merlin is arguably in terms of capability a ‘flying ASW frigate’ and its use at sea is focused on ASW platforms and the Carrier. With only 30 Merlins available, and none likely to be available or affordable, putting them on a barely capable ASW corvette makes absolutely no sense.

Even if the money existed for a purchase of corvettes, there would certainly be no money available for the purchase of more Merlins (or the refit of the ‘orphan batch’ of 8 that were not upgraded). A proper ASW platform needs a helicopter to be effective, and Corvettes would not provide this capability.

   

Secondly, the problem is one of cost and integration. A lot of commentators see the suggestion that a ship design has a hangar and assume this means it can operate a helicopter, so in turn this means a cheap design could do ASW. This isn’t necessarily the case – a cheap design will not have the necessary ability to communicate and relay information – the helicopter is an isolated combatant, not an integrated part of an ASW operation. This massively reduces its value and utility.

Finally the risk when looking at ‘cheap’ designs is assuming that they all represent the same level of survivability and capability under the hull as a modern ASW frigate. It is easy to look at a manufacturers model, read the weapon systems embarked and then ask ‘why if this is £250m does the RN need really expensive ASW frigates like Type 26’?

The reality is that beneath the surface there are enormous differences between these designs. A modern RN ASW frigate is designed to fight extremely capable opponents, such as  the Russian SSN force, in the North Atlantic in very difficult weather conditions. They are designed to be as quiet as possible and reduce the amount of noise they make, and be as difficult to detect as possible. They are also built to different standards of survivability and operating limits.

Can a cheap Corvette safely operate and fight in the same conditions as a larger Type 26 frigate? If you read ‘The Cruel Sea’ one of the key things to note was how often operations were affected by the weather, making it impossible to actually fight. Arguably the primary focus of RN ASW operations is to protect the SSBN force, which requires the ability to go to sea in all weathers. A Type 26 is big partly because it is designed to operate safely and effectively in these conditions, including issues like safely launching/recovering aircraft and ensuring that the crew are able to fight and not be paralysed by sea sickness. In the cruel Atlantic seas, size matters.  

A cheap frigate design like a corvette may sound useful, but if it makes more noise than a party of 30 toddlers who’ve all been fed Haribo and espressos then let loose with a puppy,  then it is no use. It will struggle to detect hostile submarines, and the enemy will hear it coming a long time in advance, providing enough time to stop laughing and either evade without being detected, or sink the ship and continue on their mission.

Additionally, a cheap corvette without a decent capability to engage the opponent at distance will in wartime soon be a cheap ‘ex corvette’. Unless you are properly silenced and able to sneak up on an opponent, then the reality is that if you do not possess effective long range weaponry, then by the time you are close enough to attack a submarine, that same submarine could easily have sunk you.

The days of massed frigates scurrying about firing Limbo mortars at a patch in the water while ferociously pinging away as the convoy sails past have pretty much gone now. The modern submarine can stand off at a significant distance and fire torpedoes or anti-ship cruise missiles, and their biggest concern is the risk that this activity draws attention to themselves. The game is completely different.

The reality of ASW is that it is about both players in the game wanting to be invisible to their opponent, while also being able to see their own opponent and do damage without being spotted. Cheap ASW corvette designs do not offer this ability and in the modern ASW environment are arguably more a liability than an asset.

The Royal Navy has tried twice in the Cold War to build a truly cheap ASW frigate that could be mass produced and meet the challenges of ASW. The first was the Type 14  Blackwood Frigate which was produced as a ‘second rate’ utility frigate in the 1950s. Its aim was to provide a class of ship that could escort convoys and also dish out punishment to an attacking submariner.

In some ways the class was a useful idea – in this period Soviet submarines were predominantly offshoots of WW2 German designs, and the technology available meant that they would need to come relatively close to a convoy to attack it. At this point having a mass of hulls with limbo mortars to try and sink or deter them away made a lot of sense. But, operationally the class was a failure, as submarine technology advanced it made them unable to remain relevant. The ships were quickly relegated out of the ASW role and into fishery protection or trials ships and disposed of in short order. It is also worth noting that although classed as Frigates, the Type 14 dimensions were notably smaller than the modern RIVER class OPV in service with the RN.

The second time that the RN tried for a genuine utility design of ASW frigate was in the early 1980s where to combat the threat of Soviet nuclear submarines in the North Atlantic, the RN developed various designs involving little more than a Towed Array Sonar and a Merlin helicopter. Operating in groups, these ships would have clustered around an RFA supply ship for stores, and been intended for a short life of around 18 years in the North Atlantic.

The aim was to produce a design that could protect convoys and provide efficient ASW to support the Type 22 frigates, which were at the time the lead ASW escorts of excellence for the RN. Following a variety of design changes to reflect operational experience and changes, the design eventually entered service as the Type 23 Frigate… 

This perhaps serves as a useful reminder that when looking at what the RN needs for ASW today, it is not possible to develop an effective design that can do what is needed of it on the cheap.

It is also worth remembering that for all the talk of hull numbers and growing the fleet to meet the threat, bringing ASW corvettes into service does not solve the very basic problem that the Royal Navy does not have enough people at the right level of experience to operate and crew these vessels.

ASW skills are very niche and rely on a lot of training and experience to get right. It is a slow business to learn, and one that requires people to spend many years learning how to fight a combined ‘all arms’ battle involving ships, friendly submarines, helicopters and maritime patrol aircraft plus allies and a complex, and at times overwhelming deluge of data against a foe that you will never usually see in person, and whose only sign of existence is a blurry reading on a sonar display. It is an intensely slow operation with no visible reward – and also one that is utterly critical.

For the RN, training and retaining enough sonar operators and PWO(U)’s to fight this battle, let alone the wider ships company required to operate the vessels would break the modern navy. There simply isn’t the manpower or structural capacity at the moment to absorb lots of extra small vessels in service. To meet this would require a change in manpower policy and operational focus back towards the navy of the 1970s and 80s which focused predominantly on being an ASW striking force par excellence.

Additionally, for all the talk of building extra ships, the simple question of industrial capacity is rarely considered. There is a finite supply chain in the UK and adding 20 ships to an already busy ship building programme does not mean that industry could cope. It would either need to ramp up facilities and expect its second or third tier contractors to expand to do likewise (thus raising the cost), or draw out delivery over such a long period so as to make the extra ships of little meaningful value.

People usually focus on the yards where the ships are being built to assume spare capacity exists, but it is important to remember that the hull is merely a vessel to transport the innards of the ship. It is likely that there are likely to be a number of pinch points within the supply chain that would slow down construction timelines, as the physical capacity does not exist to build the innards of the ships (such as the sensors and weapons) at a rate that is credible.

In reality, while it sounds impressive to suggest that the Navy acquire a fleet of cheap corvettes to solve its ASW problems, such a suggestion is likely to do more harm than good. These vessels would either be so cheap as to lack capacity to do the job (and thus making them essentially floating targets like the Type 14), or they would grow in cost to the point where they became highly capable and thus vastly more expensive (like the Type 23).

The wider issue is that the ASW mission is vastly different to the Cold War or WW2. There are not dozens of hostile submarines poised to come into our waters to interrupt convoys. The submarines out there are likely to be limited in number and probably extremely capable and well handled. For example, while Russia may be a barely average despotic regime with a declining economy and population, with an Army that for all the myths about it seems incapable of defeating a variety of rebels, an intelligence service that manages to meet new levels of amateurism in its bungled handling of the Salisbury poisoning, and a Navy that cannot even refit its own aircraft carrier without breaking it, they do possess some reasonably good submarines.

The small number of modern Russian submarines out there would pose a threat in conflict, but this is not a threat that a cheap corvette could easily address. Similarly, the days of sailing REFORGER convoys over the Atlantic are gone forever – the ships don’t exist and NATO hasn’t tried doing convoy work in decades. Purchasing corvettes to solve a mission that no longer exists doesn’t seem a good use of public money.

What is sensible though is to look at the RN’s current plans for addressing the ‘high / low’ force to meet its needs. The future RN will be an exceptionally capable force, built around  the Type 26/45 combination to protect the carrier and amphibious force and also handle ASW needs, it will rely on the Type 31 and River Class to conduct the lower level engagement and ‘peacetime hostilities’ missions that encompass so much of the RN’s business.

The future focus should not be on inventing a class of ship to solve this problem, but instead focusing resources on ensuring that the Type 23/26 combination remain a world beating ASW frigate, and in the unlikely event of spare cash, continue to invest in the Type 31/River class as a capable general purpose frigate.

A corvette construction programme would not solve any of the challenges that the RN has today. It doesn’t solve a gaping hole in the nations defences, nor would it necessarily provide ships for the needs that the Navy has of it. An ASW corvette would be of little use in a winters gale in the North Atlantic tracking a Russian submarine that could threaten our nuclear deterrent if it cannot operate the helicopters needed to find it, or possess the suitable sensors to track it.

At best it would represent a halfway house that would suck up much needed cash for other programmes to provide a force of ships that the RN doesn’t have enough people to crew properly and which would not make the UK a safer nation as a result. In practical terms it would be the equivalent of purchasing a convertible Austin Allegro today and stating that you now owned a convertible sports car. A result that would have been great for British Leyland forty years ago, but not necessarily the security of the nation today…