The UK’s Royal Navy just commissioned a former commercial
offshore support vessel (OSV) into the fleet as HMS Stirling Castle, a mine countermeasures (MCM)
mothership.
The ship – previously named MV Island Crown – was acquired from the commercial market for £39.8 million at the start of 2023 to provide a UK host platform for autonomous MCM payloads … [1]
So, for the sum of around $51M(US), the Royal Navy acquired a mine countermeasures ship. Of course, there had to have been additional expenses in converting it from its commercial role to a naval MCM ship although one cannot imagine the scope of work or the cost would be too significant since the roles are not all that different. Compare that cost to the cost of a new, purpose built MCM ship and the Royal Navy likely saved something on the order of $300M.
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| HMS Stirling Castle |
The salient question, though, is how well suited is the
vessel for its new role? The ship’s
duties are described as:
Stirling Castle…will now take her place on front-line duties, carrying high-tech equipment, including autonomous surface and underwater vehicles, for specialist mine hunting operations, primarily in UK waters.[1]
This is not a terribly demanding role and consists primarily of launching and recovering unmanned MCM assets, not too dissimilar from its previous role of loading and unloading supplies. Is the ship exquisitely optimized for the role? Of course not but is it adequate? Almost certainly … and for a substantial savings.
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This is exactly the kind of pragmatic, responsible action
that the US Navy should be engaged in.
At the moment, we have no viable MCM ships. The LCS remains a joke both in terms of its non-existent
capabilities and inadequate numbers.
Wouldn’t some US Navy $50M MCM motherships look pretty good about now?
https://www.navalnews.com/naval-news/2025/07/uk-royal-navy-commissions-hms-stirling-castle-as-first-mhc-mother-ship/
Performed a google search, & MCM vessels should have low accoustic signature. My take: This would mean quite a bit of modification to accomplish. As I Recall the lCS did not have low accoustic signature, with a mine detection sonar . So a MCM vessel would stand off & let the unmanned UUV do the detection ? One would think the mother ship should be able to detect as well ! Just my opinion ! PB
ReplyDeleteThere's a clear distinction between an active MCM vessel and a mothership. The former is actively involved in detection, classification, and neutralization. The latter merely hosts the assets that do the detection, classification, and neutralization. The mothership simply launches and recovers the assets ... and perhaps hosts some computer analysis of the data. The mothership doesn't need any quieting or other anti-mine features since it is not intended to go anywhere near the minefield.
DeleteYou might also recall this passage from the post: "Is the ship exquisitely optimized for the role? Of course not ..."
No one is stating that the vessel is the ultimate, most perfectly suited vessel ever conceived for MCM work. What we're saying is that, as a mothership that cost a pittance of $50M, it's perfectly adequate.
"One would think the mother ship should be able to detect as well"
Why? Would you think a destroyer tender mothership should be able to launch torpedoes or attack enemy ships? Of course not, so why would you expect a MCM mothership to be/do anything other than host the assets that actually do the work?
So, with all that firmly in mind, what problems, if any, do you have with the concept?
The RFA Proteus is another example of needing a ship
Deleteand adapting a commercial vessel in this case Multi role Ocean Surveillance. After the Nord Stream incident the RN needed something to inspect the ocean floor.
9 month to convert.
"RFA Proteus"
DeleteI'm not familiar with that one but it illustrates the concept that no every naval task/mission requires a dedicated, purpose-built, navy ship to execute. Many times a commercial vessel with some modifications can do the job just fine.
Alternatively, the Navy could be asking commercial builders to build a standard commercial ship with the minimal naval task-specific adaptations built in during construction - a commercial ship with conversion already built in. It's got to be many times cheaper than a purpose-built naval vessel.
Thanks for your explanation ! Now I see the difference ! PB
DeleteHappy to help!
DeleteIt is really interesting to note that in the age of Sails, it was quite natural to convert a captured merchant vessel to naval use. Of course it was not a Ship of the Line but did a host of smaller but essential tasks
ReplyDelete-BM
The Russians have got the largest fleet of MCM ships in the world - 47. I guess they see they’re vulnerable to a mine blockade of the Baltic choke points so planning for that. Looking to build 30 more in the next ten years. Full marks for Good Planning anyway.
ReplyDeleteGoogle search says we have 8 old Avenger Class ships in various states of rust and disrepair and that’s it. Less than third world navies.
A couple mines outside an LNG export hubs would be a disaster and we probably wouldn’t even be sure who laid them or how many there were. Why is nobody worried about this?
I like your idea of getting commercial yards to build an interim replacement class - did I understand that right? Or should we just repurpose civilian ships?
Hard to understand Navy priorities sometimes.
JM