A few weeks ago I wrote an article on how a contemporary version of the World War 2 Flower-Class corvette[1]could help the Royal Navy compensate for reduced ship numbers. What made this important, I emphasised, was the need to retain ASW capabilities at their current levels.

I was surprised and delighted by the response to the article, both positive and negative. All comments were thoughtful, interesting and well-expressed. Last week, Sir Humphrey added to the discussion on his blog[2]and therefore I thought I should provide a response not only to his thoughts, but also to other people who have commented on this topic.


01 Introduction
02  Is Russia a Genuine threat?
03  Are the UK’s current frigate plans sufficient to meet our anti-submarine needs?
04  Could more submarines be a better solution than more ASW frigates?
05  Can a low-cost corvette ever be an effective ASW ship?
06 The need to think outside the box
07 Summary

Type 26
Type 26 ASW Frigate

01 Introduction

A large number of people believe that the Royal Navy, like the Army and RAF, is under-resourced. They point to an acute shortage of surface combatants and contrast today’s fleet of 19 surface combatants to the 100-ship navy we had in 1981. But while most naval commentators share the view that the Navy has too few ships, there are some who reject the idea of a new ASW corvette. Their objections are based on the following beliefs:

  • The submarine threat is not that great and the prospect of a major conflict is unlikely
  • Our current mix of ASW assets is sufficient
  • The best way of hunting a submarine is to use another submarine, so what we really need is more submarines
  • ASW is scarily expensive, which means cheap ASW corvettes just won’t be capable of doing the job.
  • Any discussion about more ships is irrelevant, because the Navy barely has sufficient manpower to crew its existing warships.

In exploring these criticisms, the fundamental question that needs to be addressed is whether eight Type 26 ASW frigates will be sufficient to meet the Royal Navy’s anti-submarine warfare needs? Therefore, we need to start by looking at the threat.

02  Is Russia a genuine threat?

The UK believes Russia poses a serious risk to its national security. Sanctions placed on Russia as a result of its annexation of Ukraine territory angered President Vladimir Putin. His response was to initiate a range of hostile actions designed to damage and de-stabilise democratic Western governments. Hacking, media manipulation, political interference and assassinations are all hallmarks of hybrid warfare. Russia’s willingness to engage in such activities, e.g. the attempted assassination of Sergei Skripal using a lethal nerve agent in 2018, underlines its serious intent.

In February 2018, a group of mercenaries belonging to the Russian private military contractor, Wagner Group, attempted to attack an American training and mentoring camp in Syria. A battalion-size force was identified as it moved into an assault position. After US forces on the ground in Syria tried to deconflict the situation, Russia disavowed the mercenaries believing they would prevail. Wagner Group mercenaries then decided to press home their attack, failing to anticipate an immediate response from USAF combat aircraft, which decimated the attacking force.[3]Had American air power not been available, then the US Special Forces team would have been annihilated. Using expendable forces to achieve your political and military goals is proxy warfare.

In October 2018, the UK’s National Cyber Security Centre (NCSC) identified the GRU as being behind a range of coordinated and indiscriminate cyber attacks globally.[4]Cyber warfare was conducted in flagrant violation of international law, affected citizens in a large number of countries, and cost national economies millions of pounds. The UK investigation revealed that clandestine GRU activities had deliberately sought to undermine international law and compromise international institutions.

As Russia’s economy falters in the wake of sanctions, it is looking for new trading partners by expanding its spheres of influence wherever it can. It is also trying to secure access to key resources in Africa, South America and the Middle East. To facilitate this, it is propping-up despotic regimes, fuelling civil wars (first Syria and now Libya) and exporting arms. It has again employed Wagner Group mercenaries in the Central African Republic, while actively using underhand tactics to pursue opportunities in Algeria, Angola, Sudan and Egypt.

Russia also represents a threat to its former-Soviet Union neighbours. Attempts to subjugate Ukraine and Georgia, as well as Chechnya, speak for themselves. The build-up of military forces adjacent to the Baltic States has led to NATO to pre-emptively establish an enhanced forward presence (EFP) to deter further incursions.

Putin is an opportunist playing a game of brinksmanship. His audacity is attracting increasingly robust responses from NATO. He may wish to stop short of open warfare, but how often have we seen conflict result from miscalculation? Notwithstanding the threat that Russia posses to Europe, it has stifled all opposition and debate internally. The country is governed by an autocratic and oppressive regime. So, let us not be in any doubt, Russian hybrid warfare, proxy warfare and cyber warfare activities, together with direct aggression against neighbouring independent states, pose a direct and existential threat to UK interests and security. Russia has triggered a new East-West stand-off and while Cold War 2.0 may seem less innocuous than the original version, we underestimate Vladimir Putin at our peril.

A major conflict in Europe would immediately result in an air travel shutdown. Overnight, our island nation status would again make us dependent on seapower to ensure the delivery of essential supplies. Russia probably lacks the ability to prosecute a Fourth Battle of the Atlantic,[5]but, according to the IISS publication, The Military Balance 2019,[6]it has 58 submarines, of which 48 are tactical boats. Such a significant number of submarines could terrorise European and international waters. Transatlantic shipping would not necessarily need to run in convoys, but NATO would be forced to actively patrol UK approaches to counter submarine activity.

Akula Class Russian Submarine
Russian Akula Class nuclear attack submarine

If Russia were to conduct a sustained submarine campaign against merchant shipping approaching UK waters, it might not ultimately succeed; but, in the short-term it could terrorise Europe, causing widespread panic and disruption. Correspondingly, we might try to blockade Russia, to force its surrender. Our ability to blockade Russian approaches would depend on our ability to protect our own attacking forces. If such a scenario unfolded, the perceived effectiveness of our anti-submarine assets would be vital to achieve a deterrent effect. Attacks would be less likely if Russia anticipated a high cost in lost submarines.

As noted elsewhere, hunting for submarines is like looking for a needle in a haystack. Having multiple assets to hunt them is always better than having only a few. Since a ship can only be in one place at a time, absolute ship numbers are important if we are to achieve sufficient area coverage. Absolute ship numbers is also important to facilitate a controlled and appropriate response to Russian aggression. This would be necessary to avoid rapid escalation. Without having adequate anti-submarine assets, we risk being able to respond to submarine attacks only by using nuclear weapons.

While Russia is an obvious problem, China is steadily growing into an even more formidable threat. As it grows in economic power it seeks to achieve superpower status. It now has the second largest defence budget after the USA and is building military capabilities to rival it. China’s influence increasingly extends beyond Asia. Like Russia, China is active in Africa and South America. Closer to home, it is using its navy to to exercise control over the South China Seas, acting in contravention to international law by preventing vessels from transiting the area. This has resulted in clashes with the Royal Navy and US Navy.[7]Presently, China has 59 submarines, including 55 tactical boats.[8]China has an ambitious shipbuilding programme that could see its number of submarines (as well as surface ships) grow substantially over the next decade. If Russian aggression has re-ignited past tensions, the extent of China’s investment across all domains only intensifies it. Maintaining peace requires parity across multiple capabilities and a commitment to active deterrence.

HMS Sutherland – a Type 23 Frigate (Image: UK MoD)

03  Are the UK’s current frigate plans sufficient to meet our anti-submarine needs?

The submarine threat faced by Britain in WW1 and WW2, the fact that the Country’s survival was dependent on winning the Battle of the Atlantic, and the price paid in ships and sailors lost, means that we have since placed a high priority on our anti-submarine warfare capabilities. Britain’s post-WW2 investment in anti-submarine frigates has built world-class skills in this area.

Since 1990, when the Cold War ended, Britain has continued to maintain an extensive fleet of anti-submarine frigates. Despite reduced tensions, we built a total of 16 Type 23 frigates. Today, that number has been reduced to 13, but mid-life upgrades have substantially improved them. They already had powerful sensors, including bow-mounted sonars, towed arrays, and Merlin ASW helicopters, but the recent addition of Sea Ceptor / CAMM air defence VLS pods, plus Phalanx 20mm CIWS, has increased their ability to defend themselves. So, even before Type 26 arrives, the bar has been set high.

The City-Class Type 26 frigate (or Global Combat Ship) will continue to assert Britain’s leadership in anti-submarine warfare. The design is perceived to be so capable that both Australia and Canada have decided to acquire it. However, each ship expected to cost £1 billion. Part of the increase in cost is attributable to a delayed building approval. Even if the real figure is closer to £800 million, this represents a massive cost growth versus Type 23 and has trimmed the total number we can afford. The acquisition cost of the Type 23 frigate was around £130 million per ship, with a lifetime cost of around £400 million over 25-30 years.[9]The cost of Type 26 frigates explains why we will only acquire eight.

If you allocate two frigates to a carrier group and two to a Commando task force, that’s half your ASW force used-up. This leaves two frigates to patrol the North Atlantic, one for the GIUK gap and one for the South China Seas. Can this be sufficient?

To compensate for the shortage of frigates, a less expensive Type 31e light frigate has been proposed. This will increase the total number of escorts to 19; however, these are not ASW frigates, but rather General Purpose frigates to be used for non-ASW tasks. If the geopolitical situation had not materially changed since 2010, perhaps 8 ASW frigates plus 5 GP frigates would be enough, but given the threats outlined above, a strong case has emerged to support the acquisition of additional ant-submarine frigates.

I would be satisfied if the Royal Navy were allowed to increase the total number of Type 26 frigates  to 12, while adding 3-4 additional Batch 2 River Class Offshore Patrol Vessels for non-ASW roles, but this appears to be unaffordable. As things stand, the Type 31e may become be exact type of cheap warship that Sir Humphrey objects to. And he’s right. It’s pointless to spend £250 million per ship for a vessel that isn’t significantly better equipped than a River Class OPV and non-ASW capable.

If we do need additional ASW vessels, but cannot afford more Type 26 frigates, what are our options?

04 Could more submarines be a better solution than more ASW frigates?

Submarines have undoubtedly become a highly effective means of hunting other submarines. Military historian, John Keegan, one of the great Cold War strategic thinkers, suggested in his book, The Price of Admiralty,[10]that submarine warfare would take over from surface ship warfare. This view was shaped by the significant impact of anti-shipping missiles during the Falklands War of 1982, but remains relevant today as hypersonic cruise missiles loom on the horizon. If submarines are the future of the Royal Navy, then we should invest more in them.

Submarines are intrinsically quiet and the latest designs have powerful sonar equipment for detecting other submarines. Large nuclear submarines (SSNs) can perform an ASW role in deep water, while smaller diesel-electric boats (SSKs) can do so in littoral zones. While the UK’s focus has been blue water ASW in the Atlantic (and potentially in the South China Sea) we cannot ignore the littoral threat along our coastline and in the North Sea, which has an average depth of just 90 metres. However, the UK is also suffering from diminished submarine numbers. It will have just seven Astute-Class nuclear attack submarines and these are not ideally suited to shallow-water operations. Since we have no diesel-electric attack submarines, it is worth considering whether 4-5 less-expensive SSKs would be a useful addition to our submarine fleet? Some naval planners think so. Like corvettes, small SSKs are usefully cheaper than large SSNs and, in addition to littoral and North Sea duties, they are still capable enough to patrol the GIUK gap.

In the short-term, the UK’s only dedicated naval submarine shipyard, Barrow-in-Furness, is fully occupied building the final Astute-Class boats before construction of the Dreadnought-Class of nuclear ballistic missile submarine begins. If we decided to acquire new SSKs, we would probably need to purchase them abroad. Something like the German 212/ 214 Class of diesel-electric boats with Air-Independent Propulsion (AIP) systems,could be suitable. This advanced design displaces 1,800 tonnes and uses hydrogen fuel cells, giving each submarine a 12-week endurance, including 3 weeks submerged. Its non-magnetic steel hull makes it especially difficult to detect using magnetic anomaly detectors. What also makes these boats attractive is their cost:£300 million – which is much less than a Type 26 frigate.

Type 212 submarine
German Type 212 Diesel-electric submarine. Fitted with an Air-independent Propulsion (AIP) system, this is a new type of submarine that offers excellent value for money.

If submarines are the most effective submarine hunters, it is perfectly reasonable to ask the question why bother with Type 26 frigates at all?

If a submarine and a frigate were both equipped with the same types of equipment, then the submarine would be the better ASW platform. In reality, ASW frigates tend to have more capable sonar systems and superior onboard processing power. They additionally have more extensive towed arrays and, crucially, they carry anti-submarine helicopters with dipping sonars. They can execute sustained searches at distance, drop sonar buoys and use onboard weapons to destroy any submarines they find. The advantage of an anti-submarine frigate is that its helicopter allows it to search a larger area than most submarines are capable of doing.

Again, this has been said elsewhere, but ASW is a team sport. So frigates work in partnership with other frigates, their own helicopters and maritime patrol aircraft, While additional submarines may be desirable, the networked effect of a group of frigates working together can be a force multiplier that provides greater coverage. It should also be remembered that frigates are highly flexible platforms that can perform a range of tasks in addition to ASW and switch easily between them. Surface ships are also less expensive to operate than submarines.

In addition to submarines and ASW frigates, the effectiveness of maritime patrol aircraft (MPA) for submarine hunting needs to be underlined. The UK will acquire up to 9 Boeing P-8 Poseidon (based on the Boeing 737-800 passenger airliner). These cost an estimated £250 million each, or a quarter of the cost of a frigate. These can respond quickly and search large areas. While useful, aircraft are not persistent, so need to be used in conjunction with ships. A new development is aerial ASW drones like the Northrop Grumman RQ-4N Triton UAV, which is a maritimepatrol version of the Global Hawk long-range surveillance UAV. ASW UAVs are designed to work with maritime patrol aircraft, which can control 2-3 at a time, to widen the area of search. They can remain on station for longer periods of time and cost around £150 million. This makes them an attractive ASW asset. So far, however, the UK has no plans to acquire such a system.

Fincantieri Multi-Role Corvette. 

05  Can a low-cost corvette ever be an effective ASW ship?

With attack submarines, ASW frigates and maritime patrol aircraft, the UK will have a mixed portfolio of ASW assets. While submarines and MPA are highly focused resources, the extra flexibility of a ship platform when the overall fleet size has been reduced makes additional ASW vessels desirable. For this reason, my original article proposed a credible low-cost anti-submarine ship,[11]not a souped-up patrol vessel. To be credible, any ASW corvette has to deliver the following baseline requirements:

  • A hull with a low acoustic signature
  • Sufficient size to have good sea-keeping abilities, ensuring mission integrity in all weathers, which suggests a displacement of 3,500+ tonnes
  • Organic ASW sensors, so an integral bow-mounted sonar
  • Able to defend itself against aircraft and missiles, so something like Sea Ceptor (CAMM) linked to a robust air defence radar
  • Able to defend itself against other ships, so Harpoon anti-shipping missiles linked to a surface radar system
  • Sufficient onboard deck and hangar space to support an organic shipboard ASW helicopter, like Merlin
  • A 30-day / 7,000 nautical miles endurance

This list isn’t totally divorced from what a Type 26 frigate will offer, but we might need to make trade-offs in sensor quality (precision and effective range) to ensure affordability. The key question is what reduction in capability relative to a Type 26 would be acceptable? Is an 80% capability acceptable? The risk here is that we may be insisting on a Mercedes-Benz C-Class when a Volkswagen Golf does the job at a substantial discount. Of course, the opposite is also true: if a budget ship cannot fundamentally do the job for which it is designed, it is not worth the cost at any price.

So are inexpensive corvettes a fundamentally compromised concept? At the moment, we seem to be saying that Type 26 is the minimum acceptable standard for our ASW needs. It is certainly a good benchmark, but we must question the cost versus utility of every component system to see if we can achieve a comparable capability at a lesser cost. This exercise is not simply about trying to acquire a smaller, cheaper ship and fitting low cost sensors, and second-rate equipment. Such an approach would produce an inferior ship. This is Sir Humphrey’s point.

However, some of the newer light frigate and corvette designs that have emerged in recent years are compelling:

  • Atlas / Thyssen-Krupp Meko A-200 corvette (also being considered for Type 31e)
  • Fincantieri Multi-role corvette
  • Damen Sigma Class corvette

While each vessel has been designed with ASW in mind, what differentiates them from other corvettes is the weapons and sensors that they accommodate. Displacing 3,000-3,500 tonnes, they are not much smaller than many existing frigates. Specifications for other customers include capable bow sonars, generous helicopter facilities, and Sea Ceptor VLS pods for air defence. They are less expensive than a Type 26 frigate, but they are not cheap. They typically cost around £400 million, not £250 million. But even £400 million is still half the cost of a Type 26 frigate.

The Type 31e light frigate cost has been capped at £250 million. This is definitely a less expensive and less capable ship. The question is whether five ASW corvettes for £2 billion is money better spent than five non-ASW light frigates for £1.25 billion or £2 billion spent on two additional Type 26 frigates? A £400 million ASW corvette may not be as capable as a £1 billion ASW frigate, but it is likely to be superior to a non-ASW general-purpose patrol vessel.

As things stand, the Type 31e project was halted during 2018. Although no reason was provided, it appears that none of the bidders could meet the required specification for the budget. If Type 31e vessels need to cost closer to £300 million, or be reduced in specification to hit the target price – again to produce a ship without an ASW capability, this makes an even stronger case for more Type 26 frigates or a new type of less expensive ASW corvette.

The challenge is to think outside the box.

In a world where billion-pound ships can be destroyed by million-pound hypersonic missiles, our naval ship-building strategy may have become unsustainable. A low-cost approach may be our only option. This article proposes a reduction in cost from £1 billion to £400 million; but, if all surface ships become sitting ducks, we may need to start building large numbers of very low cost vessels.

We also need to re-think how we hunt submarines. Designing and building ships with hulls that have low acoustic signatures is expensive. Towed arrays are expensive. Sophisticated helicopters are expensive. Unmanned underwater vehicles could provide a fresh approach.

  • If a mother ship could launch, recover and control a number of drone-like unmanned vessels, each with its own sonar system, then having a super-quiet hull would be less important.
  • A group of networked drone vessels working together could potentially sweep a larger area of sea than a single frigate, reducing the number of high-end ASW ships needed.
  • Basic unmanned vehicles could be used to recover sonar buoys dropped by ASW helicopters, saving further money and resources.
  • Ship-launched aerial drones could operate as mini-MPAs.
  • Alternatively, we could explore the potential of smaller unmanned frigates operated remotely from the UK.

Any one of these options could create less expensive ships; they could also result in more effective ones.

Autonomous unmanned surface vessel
Autonomous unmanned surface vessels could potentially be equipped with sophisticated sonar equipment to provide low-cost ASW capabilities.

Adopting a modular approach to capability also helps. When a ship is fitted for, but not necessarily with a certain system, this provides mission flexibility – so long as the cost of fitting optional equipment is not prohibitive and can be done easily and quickly.

We also need to fix the helicopter problem.

When it comes to specifying key sub-system types, the UK has a tendency to gold-plate its requirements. Merlin is relevant to this discussion. It’s a great helicopter, possibly the most capable ASW platform in service with any navy, but such performance comes at a price. We originally bought 44 HM Mk 1 Merlins at £39 million each. We upgraded 30 of them to the Mark 2 standard from 2014 at a further cost of £38 million per airframe. Through-life support over a 30-year lifespan adds another £90 million of cost to each helicopter, and annual operating costs (150 flying hours per annum per airframe) adds £12 million. This means the lifetime cost of each Merlin is an estimated £179 million or £6 million per helicopter per annum.[12]In contrast, the US Navy’s SH-60 Seahawk cost around $30 million per aircraft to acquire with a $50 million mid-life upgrade cost and with further total lifetime costs adding-up to around $120 million per helicopter.[13]The SH-60 may not ultimately be as good as Merlin, but it is still a respectable ASW helicopter used by 15 different navies, including the US Navy and Royal Australian Navy.

The lesson here is that we can not longer specify bespoke platforms that only we use. This includes the mission fit as well as the basic airframe. We have to acquire new capabilities in partnership with our allies. And we have to focus scarce resources on the elements of the package that most deliver effect in combat.

The other problem with Merlin is that we don’t have enough of them. Of the original 44 Merlin HM Mk 1s that were acquired, only 30 were upgraded to Mark 2 status. These are all needed for Type 23 frigates (and later Type 26), Type 45 destroyers and the Queen Elizabeth-Class carriers. If we acquire additional ASW vessels, we will need to use an alternative helicopter. A Wildcat or NH90 Sea Lion equipped with a dipping sonar could be options.

NH-90 Sea Lion helicopter currently under development for the German Navy.

The other elephant in the room is manpower constraints. All talk of more ships is futile when we barely have the manpower needed to crew our existing ones. The need for additional personnel is a pre-requisite to facilitate any increase in Royal Navy ship numbers. In fact, the need to increase the headcount cap is something that applies to all three services. The Royal Navy and RAF each need an extra 5,000 personnel. The Army needs 10,000 additional soldiers. Nothing short of a major conflict is likely to result in headcount caps being lifted, but as other NATO Alliance members increase defence spending, we can only hope the UK recognises the need for additional manpower. Without increasing numbers now, in an emergency we might be forced to reintroduce conscription.

07 Summary

With more than 100 Russian and Chinese submarines roaming the world’s oceans, Britain’s 7 attack submarines, 8 ASW frigates, and 9 maritime patrol aircraft may not be sufficient.

If the Type 31e concept is flawed, because it lacks ASW capabilities, alternatives solutions could be:

  • Two additional Type 26 ASW frigates at £1 billion each = £2.0 billion
  • Four or five ASW corvettes at £400 million each = £1.6-£2.0 billion
  • Four or five diesel-electric submarines (SSKs) at £300 million each = £1.2-£1.5 billion
  • Four or five additional P-8 Poseidon (MPAs) at £250 million each = £1.0-£1.25 billion
  • Nine or ten Northrop Grumman RQ-4N Triton UAVs at £150 million each = £1.35- £1.5 billion
Northrop Grumman RQ-4A ASW UAV.

If five Type 31e frigates cost £300 million each instead of £250 million, any one of the above options would be usefully better. What the Type 31e programme can be is an opportunity to re-think future frigate needs. Reconciling costs with credible specifications will be vital.

We can compare the concept of a dual-ship fleet comprised of ASW frigate and ASW corvettes to the Army’s two tier approach to armoured vehicles. At the high level, the Army will have the Boxer 8×8 APC. This offers superb mobility and protection, but at an estimated £4 million per vehicle, it cannot be a universal platform. Instead, an additional platform is being acquired, the 4×4 MRV-P. This will also equip infantry battalions. To some soldiers, the idea of travelling around the battlefield in a lesser vehicle than the Boxer 8×8 will be unacceptable. For others, it is better than not having any kind of protected vehicle.


Notes / Sources:



[3]How a 4-Hour Battle Between Russian Mercenaries and U.S. Commandos Unfolded in Syria, by Thomas Gibbons-Neff, New York Times, 24 May 2018.


[5]The first Battle of the Atlantic was during WW1, the second was during WW2 and the third was the Cold War stand-off.

[6]International Institute for Strategic Studies, The Military Balance 2019, an annual assessment of global military capabilities and defence economics. Page 198


[8]International Institute for Strategic Studies, The Military Balance 2019, an annual assessment of global military capabilities and defence economics. Page 258


[10]John Keegan, The Price of Admiralty, Hutchison Books, 1988, ISBN 0-09-173771-0

[11]I have used the word “ship” so that we do not get hung-up on terminology. The term“corvette”is interchangeable with “light frigate,” but I have preferred the term corvette to differentiate it from a frigate on price.

[12]Based on Ministry of Defence data, FOI Request, April 2017 and Francis Tusa, Defence Analysis data.

[13]Estimate based on Sikorsky figures