HNLMS Zeeleeuw
HNLMS Zeeleeuw was the first Walrus submarine to go through IP-W. The boat is now operational, carrying the upgraded capabilities.

The Royal Netherlands Navy (RNLN) submarine service chief Captain Herman de Groot discusses the changing underwater operating environment and how the RNLN’s upgraded Walrus-class submarines and their planned replacements will meet this challenge.

Although happening in an unseen world, underwater warfare is front-and-centre in today’s returning naval rivalry. In the Cold War world, the ‘cat-and-mouse’ game involving surface ships, submarines, aircraft as the hunters, and submarines as the hunted, defined and demonstrated much of that naval rivalry. Post-Cold War, submarines continued to optimise their ‘USP’ – stealth – to bring covert capability to bear in intelligence, surveillance, and reconnaissance (ISR) activities and in strategic strike through land attack.

Today, as Western naval powers and their adversaries renew their respective interest in the strategic advantage offered by a submarine’s stealth, underwater warfare – and especially anti-submarine warfare (ASW) – is central once again.

In the Euro-Atlantic theatre, one navy whose submarine service has been at the forefront of underwater activity in the Cold War, post-Cold War, and contemporary operational worlds is the Royal Netherlands Navy (RNLN).

Since the early 1990s, the RNLN’s submarine service has been meeting the underwater threat with its four Walrus-class diesel electric submarines (SSKs). The class is currently undergoing the Instandhoudingsprogramma-Walrusklasse (IP-W) mid-life upgrade (MLU). Second- and third-in-class boats HNLMS Zeeleeuw and HNLMS Dolfijn have completed work and are operational; fourth-in-class boat HNLMS Bruinvis is nearing completion of IP-W work, and will undertake regular depot-level maintenance before returning to operations around 2024; lead boat HNLMS Walrus is scheduled to start IP-W in 2022.

From the late 2020s into the 2030s, four new SSKs will arrive to replace the Walrus boats, under the Netherlands future submarine programme. The first boat is scheduled to arrive in 2028.

With the pace of technology change accelerating and the level of strategic instability increasing, the four future submarines likely will arrive to find a much-changed operational environment. Even the four Walrus boats are operating in a maritime domain that has changed significantly from when they first arrived, and continues to change. Against these shifting strategic currents, the RNLN is having to continuously adapt how it uses submarines.

Set against this context, the RNLN is looking to maximise the submarine’s enduring strategic impact delivered by its USP, within the returning focus on high-end operations. “I think it’s a combination of going back to our roots, but in a more modern and innovative way,” Captain Herman de Groot, Commander Netherlands Submarine Service, told Armada International. “Across the armed forces within NATO, we are looking more at high-end warfare … which is why you have submarines. You can also see this in the way we are approaching our replacement programme.”

Captain de Groot joined the Royal Netherlands Navy in 1982 and has since served  onboard various submarines, commanding both the HNLMS Bruinvis followed by HNLMS Walrus. Over the years he has undertaken a wide variety of international studies and command assignments. Before taking up his current command he served as Head of the Military Strategy Department at the Netherlands Ministry of Defense from 2013-2016.

Captain Herman de Groot
Captain Herman de Groot, the outgoing Commander of the RNLN Submarine Service.

Global Affairs

Capt de Groot said there is no better example of the significant impact a submarine could have on global affairs than the recent closure of the Suez Canal, caused by the grounding of the container ship MV Ever Given. “If you look at what a six-day blockage of the Suez Canal meant to world trade …. you can do that anywhere in the world with a submarine. You don’t need 100 submarines to do that: a couple is more than enough, and it will take quite a bit of time to assemble enough ASW forces to counter that threat.”

Submarines can both create and counter such risks. To do so in the modern operating environment, submarines are blending old and new roles and capabilities. ISR operations have always been a core requirement; today, they are overlaid with the return of high-end warfare tasks like ASW and anti-surface warfare (ASuW), although with a different operating context: the increasing strategic focus on underwater operations means there has been “[a] rediscovery, almost, of ASW and ASuW in a modern environment against modern opponents,” said Capt de Groot.

Another task that came to prominence in the post-Cold War period and continues to develop in the modern, high-end warfare world is strike, both at sea and ashore. “I certainly see in [recent] years a lot more emphasis on strike power – in our case, delivering torpedoes on target,” said Capt de Groot. “There is a renewed focus on delivering weapons on target and being the striking power of the RNLN, in case that is needed.”

Operating Environment

Although Western navies are introducing new concepts to optimise and counter what a submarine brings, the nature of the underwater operating environment creates a consistent reality that any operator – both hunting and hunted – must address. This reality underlines the submarine’s enduring USP.

“For ASW – and it doesn’t matter if you fly above, float on top of, or operate underneath the waves, it is a battle you fight in one of the most difficult environments there is: salt water,” said Capt de Groot. Listing repeated technological efforts over many decades to see through the surface of the sea and to listen underneath it to negate the submarine’s unique advantage of stealth, Capt de Groot said all such efforts “have been defeated by simple salt water”. “I have heard many claims over the years that the ocean is going to be transparent …. I tend to say `wait and see’ because I’ve seen this too many times before.”

The enduring covert nature of the underwater domain means submarines will retain their strategic impact in a future operating environment that will remain insecure. “The world will not become stable out of nowhere,” said Capt de Groot. He highlighted areas of strategic competition that may emerge in the future maritime domain, including competition for resources like fuel, water, and minerals and growing focus on the seabed and the data and communications infrastructure located there. With their stealth, submarines will play a key role in competition to access and/or secure such resources. “Submarines remain one of the very few military elements you can bring out in an area without immediately taking steps on the escalation ladder …. That will remain important,” said Capt de Groot.

As regards seabed infrastructure security, he added, “More and more countries [will] start to realise how much economic infrastructure is on the seabed, and that you don’t need to attack a data-centre ashore to disrupt someone’s economy. Seabed [operations] will become one of the new missions where submarines play a role, for example as a forward operating base or command post.”

An officer onboard second-in-class Walrus boat HNLMS Zeeleeuw
An officer onboard second-in-class Walrus boat HNLMS Zeeleeuw looks at the combat management system (CMS) console, which displays the feed from the boat’s new optronics mast.

Blending Old and New

For the RNLN, like any modern navy, delivering high-end capability is increasingly enabled by the integrated use of data. The RNLN is augmenting this combination of data input and effects output in its future submarines and the Walrus-class boats (the latter, through the IP-W programme).

Two key capability developments in the IP-W programme demonstrate the benefits of integrating information, and of blending old and new capabilities.

First is sonar capability. The boats are retaining the original ‘wet-ends’ of their sonar systems – the Thomson Sintra TSM 2272 Eledone Octopus bow-mounted sonar, and the GEC Avionics Type 2026 towed array sonar.

“What I see is that computing power and development of big data etcetera provides new ways to handle the old-fashioned stuff,” said Capt de Groot. “If I look at IP-W, we are still using the same sonar ‘wet-ends’ – so, that hardware has not changed. However, if you put modern algorithms behind it and tie it to modern computers with modern ways of analysing big data streams, the picture you get from same sensor, which was designed in the early 1980s, is completely different.” “You tend to forget you’re looking at a picture provided by an old ‘wet-end’,” he added. “We’re not talking about a 10-20 percent increase; we’re talking about factors.”

In the new boats, this capability upgrade will be enhanced further with developments on the ‘wet-end’ side.

A hardware upgrade delivered under IP-W that, when combined with data analysis, is having a similar impact in improving the operating picture is the replacement of the existing navigation periscope with an L3 KEO Model 86 (mod) optronics mast. The mast is controlled using the Netherlands-designed CAMS/Force Vision Guardian combat management system (CMS), installed under IP-W and located in the forward control room: combining the mast and CMS enables the crew to integrate mast data with that from other sensors and make more informed decisions.

Using data analysis to fully exploit the information coming into the boat has impacted on operating and crewing concepts, with approaches developed for the post-IP-W Walrus boats that will be integrated into the future submarines, too.

“If you look at the optronics mast, compared to a periscope, what we saw happening there is that, for the first time, the visual picture has become just another sensor. Command has to integrate it with all the other sensors,” said Capt de Groot. The mast is operated by an able seaman. This allows the boat’s command to have greater overview of the control room and the information being generated. The mast picture is displayed on screens across the control room. “Everybody can see the picture, everybody can think about what they see on there,” Capt de Groot explained.

The RNLN is further exploiting these new capabilities and their effects by introducing new crew constructs. “The new systems provide so much more data in a much more complex environment that …[,] just as you need specialists on the platform operation side, you need specialists on the warfare side,” explained Capt de Groot. “It’s not just operating the systems; it’s actually understanding what you get in and making the right analysis based on it.” The service is developing specialists across all sensor areas – sonar, optronics, and other systems like electronic support measures (ESM) – with these specialists needing real-time data analysis skills. “For a submarine to really be able to do its business, you need to be able to do real-time analysis yourself,” said Capt de Groot. “You buy submarines for one reason: stealth …. That negates certain analysis methods you can only achieve through an ‘umbilical cord’” – in other words, a communications connection ashore. “We don’t have the option to use an ‘umbilical cord’ connected back home, with 100 scientists in the data-centre doing analysis for us.”

To grow this onboard capability, the RNLN has evolved the Walrus crew construct to include two more ratings as sensor and data analysis specialists in the control room, at the expense of two engineering ratings. The change was introduced with HNLMS Zeeleeuw, when the boat returned to operations after IP-W.

HMAS Canberra
HMAS Canberra sails with the USN’s Flight IIA DDG 51 guided-missile destroyer USS McCampbell (centre) and the Whidbey Island-class landing ship dock (LSD) amphibious ship USS Ashland during the Australia-US ‘Talisman Sabre’ exercise in 2019, off the Queensland coast. For ‘Talisman Sabre 2021’, the RAN and the USN will integrate again.

Future Submarine

Developing improved high-end warfighting output and underpinning this with the use of data and evolved crew concepts is something the RNLN is taking forward in developing the requirements for its future submarine.

For example, the optronic mast capabilities provided for Walrus will be enhanced again, with improved optronics systems being used for both the navigation and search/attack masts – delivering what Capt de Groot referred to as ‘8k’ image resolution – and with an improved CMS. “If you take an 8k periscope picture – so, the same technology you have in an 8k television – that means the actual information in the picture is better than the ‘Mk1 eyeball’. If you then have an algorithm that can search for geometrical shapes in the picture pixels …[,] detecting something like a plane is a completely different game than finding it visually,” he explained. “It has put us on the way to integrating a completely new way of thinking about the visual world.”

The submarine service is also continuing to evaluate crewing concepts for the new boats, assessing how to attract the right numbers of the right kind of people to ensure it can force generate boats and capabilities to meet operational requirements beyond 2030. As he prepares to hand over command in June 2021, Capt de Groot reflected on his time in post and said “Where we really made progress is the strategic thought process of the way we think we should run the submarine force in the future.” The key question is how the service will generate ready-for-duty submarines while balancing the needs of personnel wanting a better work/life balance, he explained. “That thought process has been started. I think we have made major progress.”

Capt de Groot noted that progressing the new boats from design into build and resolving the force generation questions will be key issues for his successor. “Buying new equipment – in my opinion, one developed over the last four years – is the easier of the two tasks,” he argued. “Coming up with a future concept of integrating young people and providing ready submarines at sea is completely different [compared to] how we have done things previously.” He added that, in a recent two-day wargame simulating operations beyond 2030, the service had successfully tested its potential new capabilities and crewing concepts in delivering future operational requirements, including for high-end warfighting.

Despite the evolving requirements and capabilities, some things in the new boats will stay the same. At 2,850 tonnes dived displacement, the Walrus boats are relatively large for an SSK: the larger size was intended to enable the boats to deploy widely at distance, across the Euro-Atlantic theatre and further afield. In the latter context, Walrus boats have deployed to the Indian Ocean to support counter-piracy operations and to the Caribbean to protect Dutch territorial interests. Today’s strategic re-focusing on the Euro-Atlantic theatre will not change this size and scope requirement.

“The focus of the navy including the submarine service is still to be an expeditionary force, which means we cannot take the risk of focusing on just one area,” said Capt de Groot. Size delivers inherent flexibility. With Walrus, he explained, “[Its] flexibility allowed us to do anything we wanted.” Consequently, with the replacement boats, “From the outset, the big question was how do we grasp that ‘free flexibility’ we got with Walrus – designed for a single Cold War task – in the design requirements for the new boats?” Such flexibility is critical, he continued: “If you look at the world stage [over the last few decades] …. we have seen so many changes, and if you compare that to the lifespan of a major weapons system, you have to have design flexibility because nobody knows what’s going to happen.” The Walrus boats were designed in a Cold War world, and were operated initially in a post-Cold War world where ISR and maritime security were the dominant submarine tasks. However, said Capt de Groot, “[There’s] been a major change in the approach to our replacement programme. It is not just about what you can do with a submarine in peacetime: it is also about what you may have to do with a submarine if it all goes to pieces.”

by Dr Lee Willett