Ukraine's Navy is Heading to the Strait of Hormuz

Ukraine still has a traditional navy-in-exile that never gets any press

Cherkasy and Chernihiv minesweepers in Great Britain. April 2024. Photo credits: Royal Navy

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Ukraine’s navy, the one Russia was supposed to have crushed in the opening weeks of the war, is preparing to deploy minesweepers to the Strait of Hormuz.

Actual ships, actual crews, for a multinational operation protecting one of the most critical shipping chokepoints on the planet Earth.

On paper, the Ukrainian Navy should’ve been a footnote by now. Russia started this war with overwhelming naval superiority in the Black Sea: Bigger ships, more missiles, deeper logistics, and a legacy fleet anchored in Crimea that had been there since the Soviet era.

Kyiv didn’t try to match it.

Instead of rebuilding a traditional navy, Ukraine built a denial force made of incredibly successful USVs which I’ve covered numerous times.

But Ukraine still has a traditional navy that never gets any press. Let’s call it TRADNAV. (I know, I’m just making up words now, but as autonomy proliferates, we’ll eventually need to differentiate between “traditional X” and ‘autonomous X.”)

Ukraine is building out a future conventional fleet abroad. Its Ada-class corvette Hetman Ivan Mazepa has already undergone sea trials in Turkey, and the second corvette, Hetman Ivan Vyhovskyi, was launched in 2024 and has been reported for later delivery. So the navy still has larger warship ambitions.

But for now, four Ukrainian minehunters are sitting in Portsmouth, Britain.

A small navy in exile…

Two former Royal Navy vessels, now commissioned as Cherkasy and Chernihiv, plus two more transferred from Belgium and the Netherlands, Mariupol and Melitopol.

All flying Ukrainian colors.

None able to get home, bottled up by the Montreux Convention’s wartime restrictions on warship transit through the Turkish straits. And they likely wouldn’t last long in the Black Sea at present.

So, Kyiv adapted. Again.

If the ships can’t reach the war, send them somewhere they’re needed. But first, let’s get into the nerdy tech details of the ships.

The Sandown class: Cherkasy and Chernihiv

The two former Royal Navy Sandown-class vessels, HMS Shoreham and HMS Grimsby before their transfer, are 52.5-meter single-role minehunters built by Vosper Thornycroft and commissioned in the early 2000s. They displace 600 tons, with a beam of 10.9 meters and a draught of just 2.3 meters; shallow enough to work effectively in coastal waters while remaining stable in open-ocean conditions.

The Sandown class. Royal Navy

The hull is the first thing worth understanding.

Sandown-class minehunters are built almost entirely of non-magnetic materials using a process called SCRIMP, Seeman Composites Resin Infusion Molding, in which resin is drawn into a sealed fiberglass mold under vacuum.

The result is a hull that won’t trigger magnetic influence mines, which is not a minor design consideration when your job is sailing directly over fields of weapons designed to detonate based on a ship’s magnetic signature.

Propulsion is equally deliberate.

These ships run on Paxman Valenta diesel engines driving Voith Schneider propellers and Schottel bow thrusters; a configuration built for precision maneuvering rather than speed.

Voith Schneider propellers work on a cycloidal principle: rotating blades whose pitch can be changed continuously during rotation, allowing thrust to be vectored in any horizontal direction without repositioning the propeller itself.

In practice, this lets a minehunter hover almost stationary over a sonar contact in a three-knot current and 30-knot winds. Its top speed is 13 knots, but speed is less important when your operational posture is to sit still above something dangerous and kill it carefully.

The primary sensor is the Sonar 2093 Variable Depth Sonar, capable of hunting mines in depths of up to 200 meters, across the entire continental shelf.

Variable depth means the transducer head can be lowered away from the hull on a cable and deployed at different depths to optimize acoustic performance depending on water temperature gradients, thermoclines, and bottom composition.

Sound propagation in shallow warm water, exactly what you encounter in the Gulf, is complicated, and a fixed hull sonar would struggle.

The detachable head solves that problem.

For mine disposal, the Sandowns were originally fitted with the ECA PAP 104 Mk5, a wire-guided underwater vehicle controlled via 2,000 meters of fiber-optic cable, carrying a 100-kilogram disposal charge that can be replaced with a manipulator, plus wire cutters to release moored mines from their anchoring columns.

The vehicle can be deployed to 300 meters depth and carries cameras and sonar to transmit sensor data back to the operations room. Later upgrades replaced or supplemented the PAP with the Atlas Elektronik SeaFox system, which we’ll come back to.

Crew complement is 34, with accommodation for 40. That’s a lean team for the amount of precision work these ships do.

The Alkmaar/Tripartite class: Mariupol, Melitopol, and the incoming Henichesk

The Belgian and Dutch transfers, Mariupol and Melitopol, are Tripartite-class minehunters, known as the Alkmaar class in Dutch service and the Flower class in Belgian service.

This is where the Cold War story of international defense cooperation gets genuinely interesting.

The Tripartite design emerged from an agreement signed in 1973 among the Belgian, French, and Dutch navies. France supplied the mine-hunting and electronics systems. Belgium handled the electrical systems and navigation. The Netherlands took responsibility for propulsion.

Each country built its own vessels to the shared design, resulting in around 40 hulls across three fleets; one of the few genuine examples of multi-nation shared naval construction in the Cold War era.

Principal dimensions sit at 51.5 meters overall length, 8.9-meter beam. Standard displacement around 510 tons at sea, maximum around 588 tons.

Its main propulsion uses a diesel system producing 1,370 kilowatts through a variable and reversible-pitch propeller. The auxiliary electric system runs two ACEC active rudders, each with an 88-kilowatt motor, plus bow thrusters.

Maximum speed is 15 knots under diesel, but during mine hunting operations the ship runs on its quiet electric system at no more than 7 knots; the noise floor of a diesel engine would compromise the sonar.

The dual-propulsion arrangement combined with two Schottel bow thrusters enables the ship to hover accurately over a sonar contact in a three-knot current, 30-knot wind; the same precise positioning requirement as the Sandowns, achieved through different engineering.

The hull is non-magnetic polyester and aluminum, no steel, for the same mine-triggering reasons as the Sandowns.

Original sensor fit was the French DUBM-21B sonar, capable of detecting and classifying objects at distances approaching one kilometer and at depths up to about 80 meters.

Beginning in 2003, the remaining Dutch Alkmaar-class minehunters were upgraded with improved electronics, including the Atlas Elektronik INCMS combat data system, Thales 2022 Mk III hull-mounted sonar, Atlas Seafox mine identification and disposal system, and a Double Eagle Mk III Mod 1 ROV (remotely operated vehicle).

That last piece, the Double Eagle Mk III, is worth a brief note:

It’s a reusable mine identification vehicle; basically a small underwater drone that swims to a contact, interrogates it with sonar and cameras, and returns.

It’s the “look before you shoot” phase of the process.

The Saab Bofors Double Eagle Mk III can also serve as a self-propelled variable depth sonar system, maneuvering in front of or below the vessel, tethered by cable, with its position tracked by an acoustic positioning system.

This gives the operator a mobile sonar platform separate from the hull, effectively solving the same thermocline problem the Sandown’s Type 2093 VDS addresses, through different means.

There is a fifth vessel, the incoming Henichesk, that deserves its own paragraph.

Formerly HNLMS Makkum (M857), laid down February 28, 1983 and commissioned May 13, 1985, the ship served with the Dutch Navy for nearly forty years including NATO exercises such as BALTOPS before decommissioning on November 25, 2024.

It was renamed after a Ukrainian naval vessel lost near the Kinburn Spit in 2022. Ukrainian personnel began training before the formal transfer, initially on sister ships including Vlaardingen, before transitioning to operational sea training.

The pipeline included English-language instruction to ensure NATO interoperability. Once commissioned, Henichesk becomes Ukraine’s fifth dedicated mine countermeasure vessel; a small but increasingly serious fleet.

The weapon they’re all built around: SeaFox

Atlas Elektronik’s SeaFox is the terminal phase of minehunting, the part where you kill the thing you found.

The SeaFox is a man-portable system at 1.3 meters long and 41 kilograms, semi-autonomous and wire-guided, capable of identifying mines with a camera linked to the surface via fiber-optic cable and destroying them with an integral shaped charge.

It has a couple operational variants.

The SeaFox-I (Investigate) is reusable, it has sonar and a camera but no warhead, and it’s what you send when you need to confirm a contact before committing.

The SeaFox-C (Combat) carries a 1.4-kilogram shaped charge warhead and is a fire-and-forget weapon: it travels to the target, re-acquires it using homing sonar, closes to detonation distance, and fires. Obviously, it can’t be recovered.

It can operate at depths from the surface to 300 meters, communicates via fiber-optic cable, and achieves up to 6 knots through four horizontal propellers and a vertical thruster.

The operation sequence is fascinating to a landlocked airborne grunt like me.

The ship’s sonar detects a contact. The contact is classified: is it mine-shaped? Does it match known signatures?

The Double Eagle or SeaFox-I goes down for visual confirmation. If it’s a mine, the SeaFox-C follows. Total time per mine is on the order of hours, not minutes.

This is deliberate, methodical work. There is no fast version.

SeaFox hollow-charge warheads are designed to neutralize all known mine types through co-ignition. Basically, the shaped charge concentrates its explosive energy in a specific direction, driving a penetrating jet into the mine’s casing or triggering its fuse.

Whether it’s a contact mine, a moored influence mine, or a bottom-lying ground mine, the physics of the kill is the same.

What they’re hunting: the Iranian mine threat

Naval mines are probably the most underappreciated weapon in modern arsenals. They’re cheap. They’re patient. They don’t need maintenance once placed. And they’re extraordinarily hard to find and remove.

Contact mines explode when a vessel touches them or comes into close proximity.

Influence mines use sensors that respond to the acoustic, magnetic, or pressure signatures of passing ships.

Moored mines float in the water, anchored by chain, and contain smaller charges optimized to damage hulls at or near the waterline.

Iran also operates the EM-52 rising mine, deployed from its Kilo-class submarines; a weapon that sits on the bottom and launches a homing torpedo upward when its sensors detect a valid target overhead.

It’s the mine equivalent of a surface-to-air missile.

Most Iranian mines currently in use are static mines, anchored at varying depths, equipped with triggering mechanisms based on pressure, contact, acoustics, electromagnetic fields, and optical sensors.

Iran has over 5,000 naval mines in its arsenal according to the Defense Intelligence Agency, and a doctrine built around exactly this scenario that dates back to the Tanker War of the 1980s.

After Trump’s folly kicked off in Iran, reports emerged of Iranian mine-laying operations in the Strait, and on March 10, CENTCOM announced the destruction of 16 Iranian minelayers and multiple warships.

SECDEF Kegseth actually stole and rewrote a quote from Admiral Bull Halsey from WWII and said “We’re sharing the ocean with the Iranian (originally Japanese) navy. We get the top half and they get the bottom half.” Which was far funnier in 1945 than it is today.

While initial assessments indicated Iran's mine-laying activity was limited, with reports suggesting a few dozen mines laid so far, but in a constricted and critical chokepoint, the psychological and economic impact of even a modest mining operation is immense. The mere threat of mines is often sufficient to paralyze maritime traffic.

This is the context in which Ukrainian minehunters showing up at a multinational planning summit in London today, April 22, with more than 30 countries at the table, lands differently than a routine coalition meeting.

The tactical problem: why mine hunting is hard

The Strait of Hormuz presents a series of compounding nightmares.

Water temperature varies significantly between surface and depth, creating thermoclines that bend and scatter sonar returns, generating false contacts and hiding real ones.

The seabed in the approaches to the Strait is not uniform; there are wrecks, debris, geological features, lost cargo containers, and all manner of other submerged fuckery that all produce sonar returns resembling mines.

NATO doctrine requires ships engaging in mine countermeasures in a hostile environment to have adequate force protection, and in the Strait, with Iranian shore-based anti-ship missiles and Shahed drones in the picture, conducting slow-speed operations within range of those systems is a significant tactical exposure.

Deploying and recovering that equipment takes time, and the ships must remain nearly stationary during operation. At 7 knots or slower, maneuvering in a contested maritime environment, a minehunter is one of the most vulnerable classes of vessel in any navy.

The politics underneath

There’s a strategic dimension here that goes beyond mine clearance.

Kyiv is aware, not without reason, of the fragility of Western support. Questions about US policy durability have Ukraine worried that Trump may align more closely with Russia after the Iran War ends.

Ukraine’s response is to become indispensable to European security planning beyond its own borders.

Showing up in the Strait of Hormuz is a deliberate signal that Ukraine is a net contributor to the alliance, not just a drain on it. Every cleared mine in the Gulf is an argument against drawing down support.

It keeps Kyiv embedded in coalitions that extend well past its own coastline.

That’s leverage, and Kyiv knows it.

The growing fleet nobody’s talking about

Ukraine’s mine countermeasure force is still expanding, which gets lost when people treat the Ukrainian Navy as though it stopped existing after Mariupol fell.

Once Henichesk is commissioned, Ukraine will have five dedicated mine countermeasure vessels: Cherkasy, Chernihiv, Mariupol, Melitopol, and Henichesk.

All of them are expected to remain based in the UK until the war ends, then make for the Black Sea for what will likely be one of the most grueling, underreported naval campaigns of the postwar period: systematically clearing Ukrainian coastal waters of mines Russia seeded across years of conflict.

That mission won’t get many headlines but it may end up being the most consequential naval work Ukraine does this year, outside of USVs.

Russia spent years trying to strangle Ukraine’s access to the sea. Blockaded ports. Mined approaches. Turned the Black Sea into a kill zone.

Now Ukrainian naval crews are preparing to protect global shipping lanes halfway across the world, using the same technical disciplines Russia was trying to deploy against them.

Same war. Different theater.

And if those minehunters deploy to Hormuz, they’ll be doing something Russia’s Black Sea Fleet spectacularly failed to do: keep the sea open.

Ukraine’s navy doesn’t look like a traditional fleet. No carriers. No cruisers. No meaningful number of large surface combatants.

What it has is a playbook, and the discipline to apply it wherever the geometry fits.

Deny the enemy freedom of movement. Use cheap systems to threaten expensive ones. Turn geography into a weapon. When you get access to more traditional platforms, deploy them surgically where they change the calculation.

Hormuz fits that model.

It’s narrow.

It’s high-stakes.

It’s vulnerable to exactly the kind of patient, technical, asymmetric pressure Ukraine has spent three years mastering.

And with Iran having already demonstrated it will mine the Strait when the situation demands it, the world just got a very expensive lesson in how much a handful of specialized ships and trained crews are worth.

A country that started this war with a shattered navy is now shaping maritime operations on the other side of the world.

That’s not something you usually see.

Then again, nothing about Ukraine’s navy has been typical. I’ll keep tabs on these vessels in the coming weeks through their Automatic Identification System (AIS) transponders, assuming they leave them on in theater.

Hopefully I’ll be able to update on their combat performance soon.

Glory to Ukraine, glory to the heroes, Crimea is Ukraine.