The Royal Navy’s first dedicated minehunting support vessel, HMS Stirling Castle, has sailed for the first time as a commissioned warship after leaving Merseyside for sea trials and training.
The milestone comes just four months after the vessel was transferred from the Royal Fleet Auxiliary.
Based at His Majesty’s Naval Base Portsmouth, Stirling Castle will serve as a “mother ship” for the Royal Navy’s new generation of autonomous minehunting systems, marking a major step in the transition away from traditional crewed mine countermeasures vessels. The ship provides a floating base for autonomous surface and underwater vehicles designed to locate and neutralise naval mines more safely and efficiently.
Commanding Officer Commander Phillip Harper praised the crew for their achievement in bringing the vessel back into service, saying, “Taking Stirling Castle out of lay-up and getting her back into service in just four months has demanded extraordinary things from my team. Fortunately, the Royal Navy is blessed with incredible people at every level, and it is their dedication, work ethic and comradeship that has got us to this point and allows Stirling Castle to join the Fleet under the White Ensign.”
Since being commissioned into Royal Naval service in July, Stirling Castle’s 55-strong crew have worked alongside RFA personnel to prepare the vessel for operations, carrying out maintenance, safety checks, and intensive training. The ship has now begun trials and assessments ahead of operational sea training later this year, after which she will undertake front-line duties supporting mine countermeasure operations in UK waters.
Originally built as the offshore support vessel MV Island Crown, the ship was purchased by the Ministry of Defence in 2023 and converted at HM Naval Base Devonport for minehunting support. During 18 months under the Royal Fleet Auxiliary, she helped develop and test new autonomous minehunting capabilities. As a commissioned warship, she will continue this work as part of the Royal Navy’s Mine and Threat Exploitation Group, integrating cutting-edge technology with crewed operations to protect vital sea lanes and infrastructure.
The Royal Navy plans to repaint Stirling Castle in standard grey livery as she transitions fully into the fleet.
She Is an Astonishingly able craft giving the ability to be in several places at the same time, whilst enabling the decomission of so many obsolete manned Mine Hunters based all over the world.
wrongly retired. and you can still see them playing their way with other navy’s. the RN mine countermeasures fleet like the main fleet has been hacked and slashed.the forgotten navy are in many the most important of the two fleets. we discard too many ships that have given long valuable service and chucked away by dusty nodding dogs at the navy who just accept it.
No other major navy its increasing the prevalence of small expensive plastic hulled boats for MCM. The Hunt and Sandown class boats are completely incapable of performing modern MCM.
What features do you think these ships have that makes them any good for MCM work?
How do you expect them to conduct MCM work? Do you think they will still be deploying cables and divers or do you accept drones are the any to go?
If so why wouldn’t you think a large vessel designed to operate drones was not the best choice?
I do sometimes wonder if the Western Navy’s move away from traditional MCMV has more to do with saving money on manpower than much else. Just contrast that with Japan and South Korea who haven’t gone down this route (though the Mogami has a secondary role as a Mother ship), they both continue to build new classes.
Of course it was. Why else did they scrap the majority of the MCMV so quickly, bar 6 Hunts and 2 Sandown, with no replacements in place beyond a handful of systems which cannot deploy without a spare Atlas or a mothership that has been laid up since October 24.
The autonomous stuff is great, but where are the Mother vessels to deploy them, and as J says below, guard them.
I just don’t see how plastic boats have a role to play when the vast majority of mines are non magnetic. Plastic boats are very expensive and fragile.
You can build a metal boat that is designed to operate drones in an MCM role but then all you are really building is an expansive boutique vessels with the same capacity to operate drones as RFA Stirling castle for an increased price.
Personally I believe drones and off board systems are the only option for modern MCM operations and if we save money and manpower we can devote it to other aspects in the surface fleet.
“What features do you think these ships have that makes them any good for MCM work?”
Our MCMV I understand have used both Seafox Drones, REMUS 300 and Divers for years to minimise their proximity to mines.
How do you expect them to conduct MCM work? Do you think they will still be deploying cables and divers or do you accept drones are the any to go?
As above. Both types already used Drones.
“If so why wouldn’t you think a large vessel designed to operate drones was not the best choice?”
Because 1 Mother Vessel, or 4 if the other 3 ever arrive, cannot replace 24 MCMV in coverage. 8 or 12 might….
With the exception of the 6 remaining Hunts, our current MCMV capability is at present so limited it is tied to keeping our HMNB clear with one Sqn of MIXG assigned for expeditionary Ops, which is essence means the Persian Gulf.
It would be interesting if the British Army acted the way the RN has done and disbanded 33 EOD Regiment, 101 EOD Regiment ( R ) 35 EOD Regiment, and 11 EOD Regiment RLC before autonomous systems replaced the poor soldiers who still might have to wear a suit to keep their body parts together if they go bang while approaching and dealing with unexploded IED’s and other munitions on the battlefield, and in 11 EODs case, the UKs streets.
A dangerous, necessary job, which their own Robots like Wheelbarrow and TG7s cannot always deal with.
I see the withdrawal of the RNs MCMV force as purely another cynical money saving exercise before the new autonomous Systems, which I understand will only be 6, are fully in service.
Another thing about those unmanned MCM systems is that they are really only able to be used inshore or in very calm sea states. The motor vessel and the platforms it tows are very susceptible to shearing and other damage in choppy seas. Something that wouldn’t be a problem with a 1000 to 2000t MCM vessel.
So do you think we need expensive plastic hulled boats to operate drones?
No arguments from me on numbers. Three to four commercial vessels and 5 type 32 armed Frigates able to operate MCM is what we need.
Yes, let’s bin all the plastics and replace them with 5 lovely T32’s.
How many decades time will we get them ?
Once the new vessels are in service, no.
We need motherships bigger than Stirling Castle as she doesn’t have the equipment needed.
It’s all moot, the RN got rid, as usual, on a wing and a prayer that MH Capability batch 2 would het fully funded.
Has it? No idea.
Yep it’s called spooky physics.. until she observes a mine she is actually in multiple places.. she only fixes a location after the mine has been observed.
The UK leads the world in this “Spooky Physics” and being able to turn up anywhere on the planet and say “Trick or Treat”.
HMS Pumpkin.
Boo 👻👻👻
.. and the thing about MCMs, Survey vessels and RFA ships being scrapped is that we are losing much secondary capability. All those mentioned have been involved in policing, eyes on the ground, search and rescue, general patrols etc. in recent years. The RN/RFA have had to use their diminished pool to multi task so we also lose those capabilities
Agreed, one of my objections.
Thankfully the RN seems to be seeing sense and realising it can’t get the RFA to operate its MCM vessels and pissing money up the wall on boutique one trick pony MCM vessels is not the way to go.
The last minesweepers we had unable to deploy to the Falklands when we really needed them and forced us to take an entire LSD away from amphibious operations to support them in the gulf.
They were armed with nothing but a 30mm gun so they had to be escorted in even moderate threat environments.
That is really why the RN needs a patrol boat function that can act as mother to the autonomous functions and has the ability to defend itself 2000-3000 tons. If they can merge it with the new optionally crewed high end autonomous platforms that would be be very very good.
This boat is all very well for exploring the use of autonomous mine warfare systems but it’s not a suitable replacement for 25 ocean going mine warfare craft.
Yes the Autonomous vessels are great but they are short range inshore vessels that can only operate in sea states below 5 and are open to being fiddling with. So they must have a mother hen and that needs to be an ocean going vessel that can defend itself and its autonomous charges.
So essentially for each autonomous system the RN needs a patrol boat sized commissioned vessel with guns to carry them.
And another fing !
Those Sandowns and Hunts gave bulk and added hull numbers whilst also showing a RN presence and doubling up as Patrol ships (amoungst other roles).
I it armed? or does its crew just stand on deck using harsh words?
Yes and Yes they stand on deck with their weapons in hand.
Scary stuff indeed.
No idea.
I suspect not at present, as I can not see her ever deploying beyond home waters currently.
And any messing with our autonomous boats in home waters I suspect would have sneaky boats and air power on the scene quickly enough.
The mothers will, obviously, need arming if we ever deploy these systems abroad or into war zones.
These “little ones” will need both parents and Grandparents in times of trouble.
She should atv least a meduim gun, machine guns and may be a CIWS, as standard, we do have a habit of fitted for but no carrying a lot on ships, no self defence seems a bit un wise
She’s not armed, and neither should she be at the moment. She’s not even painted grey at this point, she’s a platform for trials and experimentation, and won’t deploy into warzones in any near or medium term plans.
Lots seem to be missing the point of Stirling Castle.
She’s the first generation (MHC Block 1) mothership, she’s a testbed and pathfinder for future purpose-built motherships (MHC Block 2) that are purpose-built for the RN, with dedicated LARS, larger deck, higher damage control and survivability, etc.
If things don’t change, there’ll be a tender put out for 3 of these OSV motherships in November 2026. Current estimate is £400m just for the motherships.
Reckon ?
OK then, sold to the man with pointy ears !
Better pointy ears and a full wit,
than normal eyes and halfwitted 🖖🏻
Did you mean “Ears” ?
where did find tht info from, very up to date,,
Look on Navy Lookout.
thank you
Yep, all explained on NL. She lacks LARS, and is too small to operate the USVs. I think the point of many, and mine too, is that she is currently all we have as the MH Capability 2 is not yet funded, according to NL.
And we have dropped most of our conventional assets in the meantime.
No issue with the capability, just the gapping and the loss of presence conventional MCMVs provided.
£400 million? Interesting, I’d not seen a price quoted.
I thought the MHC2 motherships had a budget assigned and where looking at putting a tender out in 12 months?
Hi Dern.
I wasn’t referring to the mother vessels, but the second batch of Autonomous Systems.
We have only 3 as part of B1,as part of phase 2 we’d expand to 6.
The £400 is on the estimate on the government’s tendering website.id post the link but then this would go into ‘pending approval purgatory’…
£400 sounds like a bargain, please try to post that link.
Stick the URL protocol and World Wide Web abbreviations in front of this…
find-tender.service.gov.uk/Notice/021860-2025
Thanks for that.
The Kronsberg vanguard would be a good option for the 3 purpose built mother ships reportably wanted by the navy they could double as patrol vessels too!
After the deal with Norway on t26 the least we could do is buy something from them.
We’re buying NSM from them
So the RN has one of these ships that can only be in one place at a time, as opposed to having several dedicated MCMV hulls.
There is one tradeoff though.
Mine sweeping drones could be carried by newer Frigates and destroyers, so they can navigate through or escape minefields, should they need to.
It needs guns and AAMs plus laser weapons and a towed sonar with an onboard Merlin.
Don’t be silly.
Its not silly. With all that extra weight it might topple over.
Perfect for working underwater then.
Well they are only fisheads.
It will give them a Tail/tale to tell then.