HMS Grimsby (M108): The Minehunter Now Serving as the Ukrainian Navy's Chernihiv

Built for Precision, Not Speed

HMS Grimsby was built by Vosper Thornycroft at Woolston, Hampshire, and commissioned into the Royal Navy on 25 September 1999, a Sandown-class single role minehunter and the second ship to carry the name.

The first one is worth knowing about. HMS Grimsby was the name ship of a class of thirteen sloops built in the 1930s for colonial and escort work, launched at Devonport in July 1933, and she spent most of her peacetime service at Hong Kong. On 25 May 1941 she was escorting the tanker Helka into Tobruk, then under siege and supplied entirely by sea, when Ju 87s found the convoy. They sank the tanker in the first attack and damaged the sloop; a second wave came back later the same day and sank her too. Eleven of her crew were killed. It is a fair summary of what the Royal Navy's small ships were doing in the Mediterranean that summer, and it means the name has been on a minehunter and a sloop and nothing else.

The town it comes from has its own claim on the Royal Navy. Grimsby was for a long stretch of the twentieth century the largest fishing port in the world, and the men of Grimsby and Hull crewed a very large part of the requisitioned trawler fleet in both wars, in minesweeping and anti-submarine work of exactly the kind this ship was built for. The town then lost its distant-water fleet almost overnight when the Cod Wars ended in Iceland's favour and the fishing grounds closed, a quarrel described in the article on HMS Eastbourne (F73). Putting the name on a mine countermeasures vessel was not an arbitrary choice.

The yard that built her did not long outlive her commissioning, and it had been there for a century. John Isaac Thornycroft started building boats at Chiswick on the Thames in 1864 and moved the whole business to Woolston, on the Itchen just below Southampton, in 1904. Thornycroft was bought by Vospers of Portsmouth in 1966 to become Vosper Thornycroft, and Woolston went on turning out warships for another thirty-seven years: minehunters, fast attack craft, corvettes and frigates for half the navies in the Commonwealth and a good many outside it.

The decision to shut it was taken in 2003 and the yard closed in 2004, the business moving into a purpose-built shed inside Portsmouth naval base a few miles round the coast. The last steel ship launched at Woolston was HMS Mersey (P283), on 25 January 2003. Grimsby, commissioned in 1999, came out of that yard near the end of its life, which means she is one of the last warships built on the Itchen after ninety-nine years of it.

Rather than raw speed, her design prioritised exceptional manoeuvrability, using Voith-Schneider propulsors that allowed her to hold position with genuine precision while hunting mines, a considerably more demanding requirement than it sounds.

Her armament was modest and deliberately defensive in character, a 30mm DS30M Mk2 gun, two miniguns and three general purpose machine guns, primarily fitted for self-defence against an asymmetric threat rather than for taking the fight to an enemy fleet, reflecting the specialist, unglamorous nature of minehunting work.

The word single-role in her description is a deliberate one, and it marks a change in how the Royal Navy thought about mines. A Hunt-class ship can sweep and hunt; a Sandown carries no sweep gear at all and does nothing but find individual mines and destroy them, using a variable depth sonar lowered on a cable below the layers of water that bend sound, and a hull built of glass-reinforced plastic so that she has almost no magnetic signature to trigger anything. That is why the propulsion matters so much: hunting means creeping along a search line at walking pace and then holding an exact position over a contact while a diver or a remotely operated vehicle goes down to it, in a tideway, in weather. What that work involves, and why the Black Sea now needs it so badly, is set out in the article on HMS Blyth (M111).

The propulsion deserves more than a clause, because it is the single cleverest thing aboard and almost nobody outside the trade knows what it is. A Voith-Schneider propulsor does not look like a propeller at all. It is a horizontal disc set flush in the bottom of the ship, rotating about a vertical axis, with a ring of vertical blades hanging down from it like the legs of a stool, and each of those blades pitches continuously about its own axis as the disc goes round. Get the timing of that pitching right and the thrust from the whole assembly can be pointed in any direction at all through a full circle, and changed almost instantly.

What that gives you is a ship with no rudder and no reverse gear, because she does not need either. She can go sideways. She can turn on the spot. She can stop dead and then hold an exact position against a three-knot tide while somebody in the operations room watches a mine on a sonar screen sixty metres below and a diver goes down the shot line to it. A conventional screw and rudder can do none of that: a rudder only works when water is flowing past it, which is to say only when the ship is moving, which is the one thing a minehunter over a contact must not do.

The detail that finishes the argument is what the units are made of. They are built to be non-magnetic, mostly stainless steel with bronze blades, taking 475 kilowatts apiece through a diesel-electric drive, and they run quietly with very little cavitation. Every one of those choices exists because the thing she is creeping up on may be listening for her, may be measuring the local magnetic field, and may be counting the number of ships that have passed over it. A glass-reinforced plastic hull with non-magnetic cycloidal propellers, a diesel-electric drive and a sonar on a wire is not a warship in any sense a gunner would recognise. It is a very quiet, very patient instrument for finding things that are trying not to be found.

Sweeping the Gulf

HMS Grimsby based at Faslane for much of her career, tasked with maintaining freedom of navigation by keeping international shipping lanes clear of mines, work carried out using her SEAFOX mine disposal system and embarked clearance divers trained in explosive ordnance disposal.

She took part in regular NATO exercises including Cold Response in Norway and served with Standing NATO Maritime Group 2 in the Mediterranean, but her most significant operational commitment came in support of Operation Telic, the sustained rotational deployment of Royal Navy minehunters to the Persian Gulf, where she was based out of Bahrain in 2010 clearing mines and unexploded ordnance in one of the world's most strategically sensitive and heavily mined waterways.

HMS Grimsby underwent a major modernisation in 2012, a six month docking period at HMNB Rosyth that included replacing her fire detection system and upgrading her communications, and a further refit in 2017 fitted her with the fleet's most advanced Thales sonar technology.

Over a five year period before that refit alone, she visited more than 18 different countries conducting freedom of navigation operations, a particularly impressive itinerary for a ship whose top speed was never her primary selling point.

A New Flag

HMS Grimsby was decommissioned from the Royal Navy in October 2022, but her working life was far from over: she was transferred to Ukraine and commissioned into the Ukrainian Navy's Minesweeper Division as Chernihiv on 2 July 2023, in a ceremony held, fittingly, in Glasgow alongside her sister ship HMS Shoreham, recommissioned the same day as UNS Cherkasy. The name was chosen with real feeling behind it: Chernihiv honours a Soviet-built Ukrainian Navy minesweeper of the same name, seized by Russia's Black Sea Fleet when it overran Ukraine's Southern Naval Base during the 2014 annexation of Crimea and never given back, so a new ship now carries a name Ukraine was never willing to let Russia keep hold of for good.

She has been based at Portsmouth since April 2024, her Ukrainian crew having spent some eighteen months working through the Royal Navy's own Fleet Operational Standards and Training programme before exercising alongside NATO's Mine Countermeasures Group 1 and taking part in Exercise Sea Breeze, training that has now earned her crew formal NATO certification to operate within allied task groups. She cannot yet sail for home waters: Turkey has closed the Bosphorus to the warships of belligerent nations under the 1936 Montreux Convention for as long as the war continues, so Chernihiv and her sister ships remain based in Britain rather than the Black Sea they were ultimately transferred to help clear. As Commodore Paul Pitcher put it, ships like her will eventually prove "crucial in providing safe sea lanes" through the roughly 800 square kilometres of Russian mines currently choking Ukraine's grain export routes, a minehunter built for the Royal Navy now flying Ukrainian colours and waiting, ready, for the day she can finally go and do the job her new name was chosen to honour.

The Ukrainian squadron at Portsmouth has grown considerably since then, and it is now a real formation rather than two ships in exile. By the middle of 2026 it stood at five: Chernihiv and Cherkasy, the two ex-Royal Navy Sandowns, joined by three Tripartite-type ships handed over by Belgium and the Netherlands and named Mariupol, Melitopol and Henichesk, every one of them for a place currently occupied or fought over. In July 2026 the whole division worked off Portland on Sea Breeze 2026, the exercise having relocated from the Black Sea to the English Channel for obvious reasons, with the three newer ships working towards NATO Level One certification while Chernihiv, Cherkasy and the Ukrainian battle staff pushed on to the considerably harder Level Two. There is now a Ukrainian mine warfare force being built from scratch in a British naval base, several thousand miles from the mines it exists to clear.

And in the spring of 2026 the situation produced an outcome nobody could have predicted when she paid off in 2022. With the Bosphorus still shut to them and the Black Sea out of reach, Ukraine offered four of the Portsmouth ships, Chernihiv among them, to help clear mines from the Strait of Hormuz, where traffic had been disrupted by the confrontation with Iran. A minehunter built at Woolston for the Royal Navy, given to a country whose coastline she cannot currently reach, was on offer to reopen a shipping lane at the other end of the world on behalf of an alliance she does not belong to. Whatever comes of it, there is no better illustration of what a mine countermeasures vessel is actually for: not fighting anybody, but making it possible for everybody else's ships to move.