Category: Strategic Pings

Why the Smallest Submarines May Be the Biggest Problem in Coastal Warfare

For decades, naval prestige has favored scale. Bigger submarines. Bigger combat systems. Bigger sensor suites. Bigger budgets.

But coastal warfare has never cared much about prestige.

In the shallow, noisy, cluttered waters where chokepoints, ports, shipping lanes, and critical infrastructure converge, the modern midget submarine is making a very uncomfortable comeback. Not because it is elegant. Not because it is glamorous. But because it is useful.

That is often how real threats work.

Small Hull. Big Strategic Effect.

A midget submarine does not need global reach. It does not need months of endurance. It does not need a brochure full of exquisite blue-water capability.

It only needs to survive long enough, in the right place, to create operational or strategic effect.

That is what makes these platforms dangerous. Their small size, low acoustic profile, and ability to operate in seabed clutter allow them to exploit what I would call the littoral shadow: the messy acoustic space of shallow water, coastal traffic, thermal variability, biological noise, and bottom reverberation where traditional anti-submarine warfare becomes far less elegant.

In blue water, detection theory looks clean. In the littorals, it often looks like a bad compromise.

And that is where these mini/midget submarines thrive, laying undetected on the sea floor.

An Old Concept That Never Really Went Away

The idea is not new. The Japanese Type A, British X-Class, German coastal mini-subs, and the Italian human torpedo program all proved during the Second World War that a very small undersea platform could achieve an effect wildly disproportionate to its size.

Harbor penetration. Mining. Ambush. Sabotage. Covert insertion. Strikes against capital ships in protected waters.

The details have changed. The logic has not.

What has changed is the modern operating environment. Today’s maritime battlespace is dense with coastal infrastructure, narrow straits, offshore installations, surveillance gaps, and political gray-zone activity. In that environment, small submarines are not relics. They are highly rational tools.

The Proliferation Chain Matters

This is not just a story of submarine design. It is also a story of proliferation.

Post-war Italian designs, particularly those associated with Cosmos, provided a technical foundation for compact littoral submarines. North Korea adapted elements of that small-submarine logic into classes such as the Yugo and later the Yono. Iran then followed with the Ghadir-class, which shares a very similar tactical philosophy and reportedly similar design lineage, while also expanding its undersea portfolio with the Nahang and Fateh classes (Ghadir is basically a stretched North Korean mini-sub). North That progression matters because it shows how a niche capability became a practical regional warfare tool.

North Korea helped demonstrate what a compact submarine could do in real conflict. Iran has taken that lesson and applied it to one of the most strategically sensitive maritime environments on earth: the Persian Gulf and the Strait of Hormuz.

That is not a minor detail. That is the whole point.

The Ghadir-Class: Compact, Constrained, and Dangerous

The Iranian Ghadir-class is a good reminder that limited size does not mean limited lethality.

Because of space and weight constraints, the boat reportedly relies on a single hull-mounted passive sonar array operating in the medium-frequency range of around 1 to 10 kHz. That gives it a basic but operationally relevant ability for contact detection, target classification, and beamforming. No large towed arrays. No sophisticated sonar payloads.

But this is where people make the wrong comparison.

The Ghadir should not be measured against a blue-water attack submarine. It should be measured against its intended operating environment: shallow, congested, tactically compressed waters where engagements are short, clutter is high, and reaction time is limited. As it is shallow water, there is a cut-off frequency, making long passive towed arrays useless.

Iran has also compensated for sonar limitations by fielding a modernized optical and electronic sensor suite. The submarine is reported to carry an advanced periscope fitted with thermal imaging, day and night television cameras, and a laser rangefinder, all feeding digital displays in the control room. It also features a mast-mounted short-range air search radar, giving it improved awareness of helicopters and aircraft while minimizing exposure above the surface.

That matters. In shallow-water operations, situational awareness is often more important than elegance.

The Weapons Fit Is Where It Gets Serious

The Ghadir-class is built around two 533 mm torpedo tubes, and that alone makes it a credible ambush platform in restricted waters.

It can reportedly deploy conventional heavyweight torpedoes such as the Valfajr, but the more provocative weapon is the Hoot supercavitating torpedo, intended to reach extremely high speeds and compress reaction timelines. Whether every published performance figure is fully reliable is almost beside the point. The tactical signal is clear. This platform is designed to create chaos at short notice.

More important still is the reported ability to launch submerged anti-ship cruise missiles, including the Jask-2, which gives the submarine a covert standoff strike option. Add the ability to lay naval mines, and the Ghadir becomes far more than a coastal nuisance.

It becomes a compact A2/AD tool.

Not a fleet submarine. A denial submarine.

And in the Persian Gulf, that distinction matters a great deal.

Why Sonar Specialists Should Pay Attention

From a sonar perspective, this is a very annoying target set.

Shallow water is unforgiving. Reverberation is high. Bottom interaction is messy. Shipping clutter is everywhere. Biological noise is rarely helpful. And a small submarine operating slowly, with low cavitation and limited need to expose itself, becomes difficult not only to detect but to confidently classify. If it sits on the sea floor, almost impossible to detect with standard ASW sonars.

That is the key issue.

Detection is cheap. Understanding is expensive.

A midget submarine sitting quietly in the seabed environment is not just hard to find. It is hard to confirm, track, and act against without wasting time, platforms, and decision bandwidth. That is exactly what a smart regional denial strategy wants.

This is why large-navies-with-large-sensors should not feel too comfortable. The littorals are where elegant ASW concepts go to have a very bad day.

The Real Counter: Persistence Beats Prestige

The answer is not simply more frigates, more helicopters, or more expensive crewed platforms rotating through the same waters.

The answer is persistence, 24/7 persistence.

Persistent monitoring with uncrewed surface vessels. Persistent subsea surveillance. Smarter seabed sensors. Better acoustic libraries. Better classification workflows. Better fusion between autonomous and crewed assets.

You do not beat the littoral shadow with occasional brilliance.

You beat it with systems that stay on station longer, listen better, classify faster, and make the water less forgiving for a boat trying to disappear.

That is where the future fight is heading.

Closing Statement

The smallest submarines are not dangerous because they outperform blue-water boats across the board. They are dangerous because they are optimized for the exact waters where many navies are least comfortable fighting.

Small hull. Short profile. Strategic consequences.

That is not yesterday’s threat. It is already here.

Please comment, so we all can learn from each other.

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-04-19. Subscribe there to get new editions first.

[Cover: video]

This is a video that complements the article I wrote Yesterday. Here
is the link to my article:
https://www.linkedin.com/pulse/strategic-ping-china-just-deploying-uuvs-mapping-silence-meurling-o2slc

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-04-15. Subscribe there to get new editions first.

The recent recovery of a Chinese UUV in the Lombok Strait should not be treated as a strange maritime footnote. It should be treated as a warning.

Because this was never just about one unmanned vehicle drifting into the wrong place. It was about what that vehicle was likely doing before it was found. And that matters a great deal.

For those of us who have spent years working with sonar, seabed mapping, underwater surveillance, and the brutal realities of acoustic performance, the signal is obvious. China is not only investing in undersea platforms. It is investing in understanding the water itself. That is a much bigger strategic issue.

The undersea battlespace is changing. Quiet platforms still matter. Stealth still matters. But stealth is no longer just about hull design, propulsion, or signature reduction. It is increasingly about who knows the environment best.

And in chokepoints like Lombok, the environment is the weapon.

The Lombok Strait is not just another narrow passage in Southeast Asia. It is one of the few deep-water routes through the Indonesian archipelago that can support submarine transit at meaningful operational depth. That alone makes it strategically interesting. Unlike shallower alternatives, Lombok offers a valuable acoustic corridor for movement between the Pacific and Indian Oceans. If you want to understand where submarines can move quietly, where they may hide, and where their acoustic advantage may begin to weaken, this is exactly the kind of place you study.

Relentlessly.

That is why the technical payload matters more than the paint job or the logo on the hull.

A UUV operating in such an area is not just collecting data. It is building a model of the battlespace. With the right sensor package, it can measure currents, water column structure, seabed topography, ambient noise, and acoustic variability over time. In plain language, it can help answer the questions every submarine commander and every ASW planner cares about.

Where does sound bend?

Where does it die?

Where does the sound travel well?

Where can a submarine disappear?

And where can a submarine be found?

An Acoustic Doppler Current Profiler does not just measure current speed. It helps define the movement of the water itself, including layering and flow conditions that affect station-keeping, sensor performance, and long-endurance loitering. Temperature and salinity sensors do not just produce oceanographic charts. They define thermoclines, haloclines, sonic layer depth, and transmission loss behavior. That means they help predict where sonar performs well and where it does not. Side-scan sonar is not just for pretty seabed pictures. It helps characterize bottom type, terrain complexity, and bathymetric features that may support covert movement or influence acoustic clutter. Ambient noise monitoring helps separate biological, hydrodynamic, and commercial noise from actual targets, which is essential if you want to refine detection thresholds and improve acoustic libraries.

This is where the discussion often gets too polite.

We still hear people describe these kinds of deployments as scientific, exploratory, or dual-use. That is technically true in the same way that a rangefinder can be used for golf or gunnery. Context matters. Intent matters. Pattern matters.

And the pattern is clear.

China is steadily building the foundations for a more transparent undersea battlespace. Not transparent for everyone. Transparent for them.

That is the strategic point. If you can characterize the acoustic properties of key chokepoints, deep-water approaches, and naval transit corridors, you begin to reduce uncertainty. If you reduce uncertainty, you reduce the value of your adversary’s stealth. If you reduce the value of stealth, you begin to shift the balance of undersea deterrence.

That is not a research project. That is preparation.

The Lombok recovery also matters because it fits into a broader trend. This is not about a single vehicle, a single transit route, or a single regional incident. It is part of a larger push toward distributed, persistent, autonomous undersea sensing. The goal is not simply to place more hardware in the water. The goal is to create a better acoustic picture over wider areas, over longer periods, with less human presence and lower political visibility.

That last point is important.

Archipelagic states and maritime democracies face a difficult challenge here. Surface intrusions are visible. Airspace incursions are visible. Even fishing militia can be photographed and named. But undersea data collection sits in a murkier zone. It is often non-kinetic. Often deniable. Often wrapped in the language of marine science or civilian research. That makes it attractive. It also makes it dangerous.

Because by the time the real purpose is fully understood, the data has already been collected.

So what should serious maritime nations do?

First, stop treating Undersea Domain Awareness as an optional luxury. It is becoming a baseline requirement.

Second, invest in fixed and distributed acoustic monitoring across critical corridors, ports, and seabed infrastructure zones. Not as Cold War nostalgia, but as modern layered sensing architecture.

Third, expand the use of multi-static and bi-static sonar concepts for detecting low-observable unmanned systems that do not behave like traditional submarines and do not present a convenient surface signature.

Fourth, establish disciplined recovery, exploitation, and technical intelligence procedures for foreign unmanned systems. Every recovered vehicle is not just an incident. It is a floating database.

And finally, accept a hard truth. If your competitor is persistently mapping the acoustic environment in peacetime, they are not preparing for scientific dialogue. They are preparing for positional advantage.

The undersea domain used to favor the side that could hide best.

Now it increasingly favors the side that has measured the water first.

That is why the Lombok Strait matters.

China is not just deploying UUVs.

It is mapping the silence.

Call-To-Action

Please comment so we can learn from each other.

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-04-14. Subscribe there to get new editions first.

How USV–AUV Mothership Operations Are Redefining Protection of Critical Underwater Infrastructure

Critical Underwater Infrastructure (CUI), subsea pipelines, power cables, and global communications links form the invisible foundation of modern society. These assets that carry energy, data, and provide economic stability across oceans are quietly enabling everything from national defense to daily digital life, whilst also becoming increasingly vulnerable.

The sabotage of the Nord Stream pipelines in 2022 and the damage to the Baltic pipeline in 2023 did more than disrupt energy flows. These incidents revealed that much of the critical seabed infrastructure remains unprotected, insufficiently monitored, and difficult to defend via traditional maritime surveillance.

What makes the challenge even more complex is the nature of the threat. Many hostile actions targeting CUI fall into the “grey zone”. Though deliberate and deniable, they’re intended to avert escalation whilst still achieving strategic effects. Attribution is difficult, deterrence even harder, and episodic monitoring is no longer enough. Protecting CUI now requires persistent, high-resolution, and cost-effective underwater surveillance on a continuous basis.

Why Traditional Surveillance Models Fall Short

Established approaches to subsea monitoring struggle to meet this requirement. Fixed seabed systems, such as hydrophone arrays, provide persistent monitoring but only at known locations. Once identified, they can be avoided, spoofed, or neutralised. Their static nature is both an advantage and a limitation.

Crewed vessels deliver mobility, but at a prohibitive cost. Daily operating expenses routinely exceed tens or hundreds of thousands of dollars. Their acoustic and visual signatures are unmistakable, making discreet monitoring impossible. Most critically, launching and recovering underwater systems in real sea states exposes crews and equipment to considerable risk.

Standalone AUV operations solve some problems, but cause another: endurance. Battery limitations typically restrict missions to less than 24 hours. When depleted, the AUV must be recovered, recharged, and redeployed. The result is a stop-start surveillance model, punctuated by gaps precisely when persistence matters most.

In short, today’s tools were never designed for continuous, wide-area CUI protection.

The Shift: USVs as Motherships, AUVs as Persistent Sensors

A new operational model is emerging that fundamentally changes how subsea infrastructure can be protected.

At its core is a symbiotic USV–AUV concept: Unmanned Surface Vehicles acting as autonomous motherships, supporting and sustaining fleets of Autonomous Underwater Vehicles.

This does not concern replacing ships with drones. It is about breaking the endurance barrier and creating a system where at least one AUV is always in the water – surveying, mapping, and monitoring critical infrastructure – while others recharge, upload data, or stand by. Persistence becomes the standard, not the exception.

The Operational Principle: Continuous AUV Rotation

The model is simple yet operationally effective. A USV deploys a fully charged AUV to survey a defined CUI corridor. As that AUV approaches its battery or mission limit, it autonomously returns to the USV. A launch-and-recovery system (LARS) enables safe, automated docking, often without the AUV even leaving the water. While the returning vehicle recharges and offloads data, a second AUV is deployed immediately.

The result is a continuous rotation cycle: 1 – one AUV surveying; 2 – one AUV charging; 3 – one AUV processing or standing by. There are no surveillance gaps, no need for crewed recovery, and no dependence on weather windows to dictate operational tempo. This capability establishes the USV as an effective force-multiplying mothership.

Why Multi-AUV LARS Is the Enabler

The most critical function of the USV in this architecture is launch and recovery, rather than navigation or endurance. A multi-AUV LARS transforms the USV from a basic platform into an autonomous subsea operations hub. It enables safe handling of multiple AUVs in real sea states; in-water docking for charging and data transfer; and elimination of deck-based recovery, the riskiest phase of any subsea mission.

Removing personnel from launch and recovery operations significantly increases safety. Meanwhile keeping AUVs submerged during servicing further increases operational uptime. In this case persistence is no longer limited by weather, daylight, or crew availability.

AUVs: High-Resolution Eyes on the Seabed

In this model, the AUV serves as the primary sensor platform, operating directly where CUI is located. Medium-class AUVs offer an optimal balance of payload capacity, endurance, and autonomy for monitoring infrastructure. Equipped with high-resolution sonar, such as Synthetic Aperture Sonar (SAS), they deliver centimeter-scale imagery across wide areas of the seabed. This level of resolution is essential, not optional.

It enables detection of subtle seabed disturbances, newly introduced objects, cable exposure, or burial changes, and provides evidence of tampering or pre-positioned devices. Importantly, it also enables repeatable and comparable surveys, supporting accurate pattern-of-life analysis along critical routes.

From Seabed to Shore: Turning Data into Decisions

Persistence alone is insufficient; data must be transferred securely and efficiently. In the USV–AUV model, data flows seamlessly: 1 – raw sonar data is collected by the AUV; 2 – data is transferred during docking to the USV; 3 – data is then pre-processed onboard to flag anomalies and reduce bandwidth; 4 – pre-processed data is transmitted via encrypted satellite links to shore-based command centres.

The USV acts as a mobile data gateway, providing near-real-time intelligence to national or alliance-level command systems. Once integrated into a wider Maritime Domain Awareness framework, this continuous data stream enables a shift from reactive response to proactive infrastructure defense.

Strategic Advantages That Redefine the Mission

The benefits of this symbiotic model are transformational, not incremental.

Persistence at Scale: Weeks or months of uninterrupted monitoring replace short, disconnected missions; Reduced Risk: No crews are exposed to hazardous launch and recovery operations; Operational Discretion: Low-profile USVs and submerged AUVs significantly reduce detectability; Economic Viability: Replacing crewed support vessels with autonomous motherships makes persistent surveillance financially viable; Scalability: Multiple USV–AUV teams can be deployed simultaneously throughout vast infrastructure networks.

Together, these advantages make unmanned systems a significant force multiplier for CUI protection.

A New Doctrine for Underwater Security

The protection of Critical Underwater Infrastructure is no longer a niche technical problem, it’s a strategic requirement. The USV–AUV mothership model offers a forward-looking doctrine – one designed for endurance, ambiguity, and scale. By making sure that there is always an AUV in the water, it delivers the persistence required to deter, detect, and document hostile activity in the subsea domain.

While this model is highly relevant for CUI, its implications reach further to mine countermeasures, ISR, and long-term seabed monitoring. At a time when underwater infrastructure has become both a target and a strategic lever, adopting persistent, unmanned, and integrated surveillance architectures is no longer optional. It’s the new baseline for maritime security.

Call-To-Action

Please comment so we all can learn from each other.

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-04-07. Subscribe there to get new editions first.

[Cover: video — Made by Thomas using AI]

Yesterday I submitted my latest Strategic Ping Newsletter – Evolution
of Sea Floor Mapping.

Here is a movie I made using various AI tools, illustrating the
evolution from lead line to modern MBES.

LINK:
https://www.linkedin.com/posts/thomasmeurling_strategicping-hydrography-multibeam-activity-7444783565403492353-uQC4?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAC91OQBPgogARmVAy5SK1cl5Uvy2ygxAHI

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-04-01. Subscribe there to get new editions first.

Hydrography has always been about one thing. Reducing uncertainty before uncertainty becomes expensive.

The Egyptians understood that. Long before sonar, they were already measuring water levels and restoring order after the Nile floods wiped out boundaries and infrastructure. Their tools were simple, but the principle was powerful. Measure carefully. Repeat consistently. Turn water from chaos into something you can manage.

That, in essence, is still hydrography.

[Video: Evolution of Hydrographic]

For centuries, the lead line was the main tool of the trade. A weighted rope lowered to the bottom. One depth point. One moment in time. If you were lucky, a little tallow on the lead would also bring up mud or sand, giving you a clue about bottom type. It worked. Sort of. But it was painfully slow, highly manual, and left enormous gaps between soundings. In other words, it gave you information directly under the vessel and a healthy amount of optimism everywhere else.

Then came the fathometer.

In the 1920s, echo sounding changed the game by allowing surveyors to measure depth acoustically while underway. This was a major step forward. No more dropping a line over the side every few minutes. Now we could collect a continuous depth profile along track. Productivity jumped. Confidence improved. But there was still a problem. A single-beam echo sounder only looks straight down. It tells you what is below the keel, not what is waiting a few meters off to port. Or starboard. Or directly in the gap between survey lines where nasty surprises like to hide.

That is why multibeam mattered so much.

Multibeam did not just improve hydrography. It changed the question. We stopped asking, “What is the depth under me?” and started asking, “What does the entire seabed look like across my swath?” That is a very different level of ambition. And it is the reason hydrography moved from sparse measurement to true seafloor mapping.

One of the important commercial milestones in that transition was the SeaBat 9001. It helped bring multibeam out of the realm of specialist systems and into practical survey operations. Compact. Commercial. Usable. It made it possible for more operators to move from isolated soundings to real swath bathymetry. That was a big deal. Once people saw proper coverage, going back to sparse data felt a bit like going from radar to binoculars and calling it progress.

Then came the systems I know personally.

I had the privilege of helping to lead the development of the SeaBat 8125 and, later, the 7125 as R&D Manager for RESON Inc. The SeaBat 8125 was based on Jens Steenstrup’s (co-founder of RESON) brilliant ideas, with Mark and Kirk as lead engineers. This was a major leap in shallow-water hydrography. It delivered extremely high resolution, using focused beamforming, and helped redefine what surveyors expected from multibeam performance in ports, harbors, and coastal approaches. It was not just about measuring depth better. It was about seeing the seabed with a level of clarity that changed operational standards.

The 7125 took that further. Dual-frequency capability. Greater flexibility. Better coverage. More productivity. Better data in more conditions. This is where multibeam matured from a clever sonar into a true survey system. When operators can reduce infill lines, maintain data quality, and get cleaner results faster, that is not a small engineering improvement. That is commercial and operational leverage.

And then we arrive at the SeaBat T20 & T50.

The T20 & T50 represent the next stage in the evolution. Frequency agility. Advanced beamforming and better sidelobe suppression, resulting in cleaner bathymetry.

Better integration with inertial navigation. Higher data density. Less time fighting artifacts in post-processing. In simple terms, it reflects where hydrography has been heading all along. Not just toward more data, but toward better data. Data you can trust. Data that shortens the path from acquisition to decision.

That is really the story here.

The evolution of hydrographic survey is not just a story of better sensors. It is the story of reducing ambiguity. From Egyptian measurement staffs to lead lines. From lead lines to fathometers. From fathometers to multibeam. From multibeam to agile, high-resolution systems like the SeaBat T50/T51.

I give the examples of SeaBat sonar family, as that is what I’m most familiar with. Similar MBES to T50/T51 would be Norbit Winghead or Kongsberg EM 2042, all excellent MBES systems

We no longer just sample the seabed. We model it. We interpret it. We operationalize it.

And that is a very good thing.

Because the ocean has always been unforgiving to people who confuse limited data with real understanding.

Call-To-Action

Please comment and provide insight so we all can learn from each other. Did you ever used any of the older SeaBat MBES systems?

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Originally published in the Strategic Pings ))) newsletter on LinkedIn on 2026-03-31. Subscribe there to get new editions first.