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Phillip Johnson

Cut to the chase, the T31 exists because there was not enough budget for an adequate number of T26’s, nor likely the industrial capacity to build more T26’s to an acceptable timescale.
The T31 has reasonable capabilities if you compare it against a Batch 2 OPV, beyond that they are not deployable against vaguely high end threats and the outcome will likely be deadly if they are.

Craig Lewell

It has Sea Ceptor to deal with high end air/missile threats and will have Naval Strike Missiles for high end enemy Frigates and which is incidentally what the US Navy will be using on their Constellation class frigates (albeit more of them).

The interesting thing in this article is the indicative general arrangement diagram which shows a bow sonar, I thought that they were not going to have sonar?


12 Sea Ceptor vs a minimum of 48 ESSM on Constellation.


I think the image is of a general configuration. It seems that it will have 24x sea ceptors, unless it has changed (Link). On 2 November 2021, First Sea Lord Tony Radakin stated that Type 31 frigates will be fitted for but not with the Mark 41 Vertical Launching System. Here are different configs (Link)

Supportive Bloke

On Sea Ceptor nothing has been announced on numbers for T31.

I think the first time we will know what has been fitted is when George, on the other side UKDJ, flies his drone over the first T31 to be launched!

Radakin was clear that he wanted Mk41 on T31 – that was on video at the Defence Select Committee. It is the kind of up arming that would not cost a massive amount (common with T26 and the parent IH) and TACTICOS is already integrated with Mk41 on other ships. So it wouldn’t be particularly risky either and would add a massive amount of firepower to the ship.

The big issue the RN has is volume of missiles for land attack and slots for other goodies in smaller numbers.


Mk41 may not be the best system nowadays and all options should be reviewed, but 32 strike length VLS should be the minimum for T31/32.

with the advent of drones a separate VLS for these will also be needed.


They have to fire 2 essm to our 1 seaceptor so 24 is enough.


Are we sure about that… Source please?


Its normal USN doctrine to fire 2 missiles at each target


It is US (& a few others) doctrine to fire 2, just to be sure. As the missile count gets closer to UK numbers, I am sure they will reduce. If you have 96 missiles you can afford to fire 2. If you only have 12 you can’t. A single mk41 unit can handle 32 ESSM/CAMM). Block II ESSM is already a thing. ESSM is CAMM-ER range & block II is dual semi-active/active capable.

48 ESSM BII or 24 CAMM? We are not even sure T31 will get 24, let alone CAMM-ER. ESSM can intercept at twice the range of CAMM.


Type 31 cost £250m each
Constellation Class cost £1bn each
Same number of missiles for your money!


To my mind the lack of ASW capability is far and away the biggest capability gap in these ships and is a much higher priority than Mk 41 VLS

Gavin Gordon

Above at least seems to offer the option as ‘circumstances dictate’ (short title Mad Vlad):-
‘Original manufacturers have provided details to construct CAD models for items including the BAES 127mm Mk 45 Mod 4 Medium Calibre Gun and the Thales CAPTAS towed array sonar series’.
What did catch my eye is the variable pitch screw, as I know RN weren’t keen due to turbulence issues. But then maybe the trade-off between running the diesels at their most optimal &/or quiet revolutions was better than running the engines at higher revs for greater knots as per fixed pitch.
Overall, have always approved of the whole T31 process, though.


T26 is designed for ASW, but huitfedt is pretty good and T31 seems better.

the ability to add captas 4 will give that capability if required, so I do believe it’s covered.


It’s also worth noting that UUVs may take over the role of captas longer term and may actually be better and easier to deploy.

I am ok with T31, it’s a systems ship.

my only grumble is lack of VLS which they will sort out and the guns which should be CTA for commonality and save money as we have them and the ammo factory is uk based.

apart from those 2 tiny issues it’s great value at sub £300m


I agree. The ship will be blind to underwater threats with no bow mounted sonar or towed sonar array. It will have a towed anti-torpedo array. If Type 31s go to sea with Wildcats rather than Merlins, as seems likely, it is worth noting that Wildcats don’t have dipping sonars or provision for anti-submarine torpedoes.

HDML 1963

It astounds me that the prospect of constructing a large escort vessel that lacks a sonar system (or TTs for that matter) could even be seriously considered. Yes the hull may well represent a somewhat sub-optimal ASW platform in terms of sound deadening, but sub optimal is not the same thing as useless. In any case sonar’s can also play an important role in mine avoidance and incoming torpedo detection aside from sub hunting. One suspects that all export versions of this design will come fitted with sonar as standard of course – as does the Danish design they are based upon I note.

In many ways I like this ‘off the shelf” design approach – I like it a lot actualy. However, if the Type 31 class are actualy delivered into service sans any meaningful ASW capability then they will not be fit to fly the White Ensign.

Pete Lloyd

As any sonar operator will tell you.Hull fitted sonar are not great alot of the time.


Yes. The ASW sensor systems has moved on and now finds towed and variable depth sonars a better system.
The under hull ‘domes’ are likely only useful for detecting torpedoes closing in.

Supportive Bloke

Or for active use when they do get very good range and resolution?


I think Type 26 will have a hull sonar.

Last edited 1 year ago by AlexS

Yes it will – ST2150 made by Ultra Electronics.

Supportive Bloke

Certainly true for passive use.

You cannot lower the hull mounted sonar through the thermoclines etc…..whereas you can lower the tail.

Don’t tell the hull sonar obsessives that: there will be a lynch mob if there are too many facts…..

That said, active hull sonar can be a great deterrence as a sub will be very afraid of being painted.


Well I am old, so 2016 was the big thing in my day, starting out in the ASW specialist T22, then retrofitted to Exocet/Sea Wolf Leanders, and then to T42’s – so “not great” versus “nothing at all” ? Why wouldn’t we accept the “not great” and fit at least some capability, if not hull mounted then Thales does cheaper versions of CAPTAS than the Mk4.


There isn’t sufficient money in the U.K. defence budget to do all the “nice to do” and higher priorities. Everything has to be judged against every other possible use of the money. Only those things that are best VFM get funded.


“No hull sonar” is claimed bad so many times, but I do no think it is a big issue.

1: Ship torpedo defense kits are the most essential part, and T31 carries it. Can to torpedo detection and risk assessment, soft-kill the torpedo.

2: hull sonar onboard a frigate is known to be very inferior in ASW game against SSK/SSN. It will force the enemy SSK/SSN to avoid the frigate (which is important in some sense), but the frigate will not be a good hunter of SSK/SSN.

Adding a hull sonar to T31 might be “good”, but I do not think it is critical. And, there are many “good things” to be done in RN/RAF.

  • buy a few SeaGuarding UAVs with ASW kits, to cover much wider area with sono-buoy fence.
  • buy a few-sets of ARCIMS SeaSense ASW kits to provide choke points ASW? The USVs themselves can be “shared” with the mine-sweep system.
  • how about the containized CAPTAS-1 system (now on trial with French navy), which could be carried and rotated among River OPVs, HMS Enterprise, T31s, and even Mk.10 LCUs?

Adding a hull sonar to T31 is only one of the options like them.


Containerised solutions sound good but my understanding is that the River class are relatively noisy so perhaps not best for ASW operations.


These are patrol frigates. Not ASW frigates. If you want to operate in the littoral, hull mounted sonar works. You are more interested in finding mines & keeping submarines away rather than looking for submarines in order to sink them. That’s T26’s job. You find one – great, but any sub detected will be trying to get out of the way, ASAP. Sometimes keeping a submarine away is more important than sinking them. Eg amphibious operations or in chokepoints.


Rubbish. The only way to keep a submarine away is to locate it and sink it. Full stop. As you point out these are not ASW frigates which means that in ten years time the Royal Navy will probably have six ASW frigates at its disposal whilst the Chinese and Russians boats will be queuing up to get into the North Atlantic.


The issue with the RN’s force structure of non-multi purpose escorts is the (high) risk of the wrong boat being in the wrong place. There is no point in having the T26 in the fleet if it’s 5,000 miles away and the T31 is the only thing on scene. This was a lesson from the Falklands that seems completely lost now.


I’m in favor of a hull-mounted sonar if for no other reason than the fact that you may lose a VDS or towed array in certain scenarios. Then what? You’re completely blind. Further, having a hull-mounted sonar is helpful before you deploy the towed array or VDS. They go hand in hand.


USN Constellation class FFGs also will not have a bow-mounted sonar. Big mistake IMO for an ASW frigate. T31 isn’t an ASW asset, unlike the T26.

david anthony simpson



They may be upgraded and become better ships in time. And I might go to the gym five days a week and become a body builder. Until either of those things happen the T31 (as we currently understand its capabilities) is little more than a large OPV and I’m a puny weakling.
The T31 is inferior in almost every aspect of warfare to the T23 GP it replaces.
The recent announcement of buying NSM (presumably destined for T31 and T45) does leave it with decent ASuW capabilities.
But 12 SAM’s vs 32 SAM’s and no sonar and diesel running gear vs an excellent hull sonar and quietened running gear leaves it a very poor second to the T23 in AAW and ASW.
Discussion of further investment seems to centre around the Mk41 VLS but to me that’s a far lower priority than a good sonar and another 12 SAM’s.


The Type 31 is not designed to be an anti submarine warfare platform, that is the role of the T26. You even state that it is intended to replace the GP variant of the T23.


You’re right. Their design makes them poor ASW platforms which is why they are not the ships we need given that the T23 GP they’re replacing are very capable ASW ships with quietened machinery and an excellent hull sonar?

Last edited 1 year ago by Sunmack

FFS everytime………..



That explains why we have a specialised T23 for ASW then ^^


General Purpose does NOT mean multi-purpose


If it is GP then it should be capable of ASW even if not at same Type 26 class.

What Type 31 shows is that strangely a ship more appropriate for an empire, to do gunboat diplomacy.


How do you conduct legitimate ASW with 9 ASW platforms? Answer: you don’t.
You need as many assets as possible capable of as many missions as possible, especially when you have a limited number of platforms. What’s the cost of adding a hull-mounted Thales sonar? Maybe $5-$10M. I think it is worth it in the long run, and both the RN and USN are making a mistake by not equipping every one of their frigates with a hull-mounted set to complement their towed arrays and/or VDS.


Given the acoustic limitations of the T31 is it worth putting expensive sonar on the class?


That’s a fair question mate. Unfortunately we’re stuck with them so have to try and make the best we can out of them despite their limitations


Only if the plan is to use them against submarines. In reality I don’t think the RN see’s the T31 as part of its main combat fleet. They will spend their time operating in areas considered too dangerous for an OPV, but where an RN presence is considered necessary. If significant combat breaks out a T31 would withdraw and depending on the situation a significant task force might be deployed.


It never works out that way. When the proverbial hits the fan everything grey gets sent. T21 were supposed to be patrol frigates but were sent to the Falklands where their obsolete SAM led to the loss of two ships and many young men.
The T23 GP does not need to be withdrawn from threat areas as it has full spectrum warfighting capabilities. T31 is a £2bn downgrade on our existing SAM and ASW capabilities.


But just how much ASW capacity do the GP T23’s have? No towed array and a bow sonar that like the one on the T45 may or may not be manned.
After all the issues in Afghanistan over troops going into combat without appropriate equipment I’m not sure the RN would “sent everything “ these days. Particularly when the situation isn’t a direct and immediate threat to the U.K.


The only reports I’ve seen with respect to unmanned sonars relates T45.
T23’s all have the same excellent hull sonar and are quietened for ASW. While GP’s lack a towed array they are otherwise excellent ASW ships.
You give politicians too much credit in terms of how long their memory lasts. Sending ships with obsolete self protection to the Falklands resulting in dozens of deaths didn’t give them pause for thought about sending guys into Afghanistan and Iraq with inadequate gear.


T23ASW’s bow sonar is upgraded to S2150 standard, replacing the signal processing system. T23GPs has S2050 sonar, not upgraded. As signal processing is essential in these days, there will be a big difference between the two. Just a comment.


T23 have electric propulsion. Then they have a sizable hull sonar not an after thought.


Its a gas turbine drive AND electric from diesel generators
The gear box combines the GT or electric motor to produce the power to the props


The type 45 sonar which was rudimentary at best has not been manned for years. That is a very open secret.

Last edited 1 year ago by Esteban
Supportive Bloke

With that I totally agree.

Counties & T21 had no proper defensive fit and so should never have been sent to war in ’82: totally agree.

That in now way denigrates the very brave and resourceful crews who did great work on shore bombardments and with their embarked helicopters.


Absolutely mate. Those young men were professional as ever.


Interestingly even the T42 batch ones did not have a great self defence kit. The fact the RN stood off an entire airforce and navy while supporting a large scale amphibious operation in some quite restrictive waters ( while lossing ships) and still completely destroyed the Opposition when they were in that airforces and navies back yard and 8000 miles from home…has to be a bit of a benchmark of how good the RN is….( it was very well documented by the USSR itself that it rocked them back on their heals a bit, and made a difference to the final outcome of the Cold War) all the while it had very much been suffering political pressure to turned it into a NATO North Atlantic ASW asset.


Think the new offboarding systems will take over you can drop them 50 mile ahead of the shop and get a picture of what’s ahead of you, biggest issue will be can we do anything about it when we get there. The t23 never hah towed stays and the bow sensors were useless which is why when they broke they weren’t replaced. Most of the the GPS never had asham as we only had five sets shared amongst the fleet


This goes back to the days of T22 B1 being much more noisier than Leander. Being quiet is important. And irrespective of whether the diesels are rafted, should be but I doubt it, some thought would have be given to making the ship quiet. It will be the prop where that effort will be concentrated. The Danes have just redesignated the Absalons as ASW hulls. We shall see yet again. Never underestimate the RN’s ability to snatch defeat from the jaws of victory.


Don’t tell me Type 31 is noisier than a frigate from 70’s and 80’s that had sonar…


Its fun game , where the Leanders which were designed without much knowledge of ‘quiet propulsion’ and maybe had a bit of work on the propellers only , were somehow quieter than most classes that followed when the whole engineering of quieting inside systems became understood


Right some points from a former WE who spent many a sleepless night doing CASEXs on T42 (S2016) , T22 (S2016, S2050, S2031), T23 (S2050, S2031) and yes even an LPD.

T42 and T22 had hull sonars that where effective active sets ( S2016 and S2050) The mechanical machinery was not in the same class for ASW quietness as in T23/T26 but it still allowed you to hunt subs. Some later T22 had S2031 Passive tails but the machinery fits ,DG Sets, GTs, gearboxes and CP props where again not ideal for quietness. That didn’t mean you couldn’t hunt subs or track them at a good range passively, you could and we did on many occasions.

T23 (I had a passive Tail equipped and GP versions) are with the exception of the tail the same ship. Very Very quiet and very good ASW assets. The 2050 sonar could track targets, determine speed and aspect ratio at a ridiculous range ( environmentals dependent) S2050 had a passive capability for torpedo warning and passive detection but nothing like a tail gave you. T23 with a tail configured for quiet state is a hole in the water. A Lepers bell( a sonar chirper) was a requirement during CASEX for sub safety to ensure subs could work out where you where. A number of close calls between early T23 and Subs on early CASEX’s brought this requirement in.

So to T31 (and yes some of this is supposition but based on previous and current experience). It will have Main Propulsion Diesel Engines (MPDE) . If its like any of the other nations MPDE powered ships I have worked on, these will not be bolted directly to the hull. They will be on there own vibration mounts and any fixed pipe connections will be via flexible rubber spool pieces. I expect the engines will be within there own accoustic enclosure anyway. The engines will be very accurately aligned and connected to gearboxes via large flex couplings and the gearboxes then output to the shafts. The Gearboxes will (I am guessing here) be bolted to the hull as they are on the vessels I have worked with. Modern gearbox design means any transmitted noise should be minimised but not eliminated . CP props are noisier and more complex than fixed props. The USN has fixed Props on the Connies. FREMM ,which the Connies are derived from, uses CPP so yes CPP is a compromise for ASW. CPP does let you do a decent speed on MPDE and T31 is a GP Frigate from build unlike the T23 which inherited the GP moniker when the Cold war ended and the RN saw no need for them all to have tails.

I see no reason why CAPTAS cannot go onto a T31. (Its going onto USN Connies and they are not getting a bow sonar either.) Self generated noise may be an issue on T31 but machinery running states and HVME ( Hull Vibration Monitoring Equipment) should help reduce that. How low will be the T31 radiated noise? That will be a well guarded bit of info but I would expect it to be at a level near that of a current FREMM. Dont forget CAPTAS is an Active LF/ Passive sonar set so it does transmit.

Where I am now there are drone boats, including those fitted with towed bodies plying their trade every single day. (There are also MTP wearing personnel adding their input to the work). The MCMV force is leading on drone use . In future being able to deploy, away from a mothership, a standard RN 11 m Atlas Workboat with perhaps a thin line array (Krait) would be a huge advantage. These workboats are the same design as the MCMV drone boats and built to take modular packages on their decks. The Krait array has already been trialled on the 11m workboat.

And before anyone asks yes we did do ASW on an LPD as the ASW Commander. No sonar, no Helo but lots of data links. We coordinated via the command system and our own data links and comms ,active and passive surface units, dippers and ponies to hunt a sub. Are deck was the lilly pad for refuelling. Its an exception rather than a rule but you can do it.
In reality if you are hunting subs in a real shooting situation you are not going to be a singleton. Every man and his dog will be involved. So son of SOSUS at Dam Neck, SURTASS, P8, Surface ships(active and passive) , Drones, Subs, Dippers.

Right enough reminiscing…back to fixing war canoes and overseeing an MPDE change (V16 Cyl Paxman) !


How low will be the T31 radiated noise? That will be a well guarded bit of info but I would expect it to be at a level near that of a current FREMM. 

What you talking about!?
Are you making equivalence of a diesel powered T31 GP frigate to an ASW frigate like FREMM that is electric powered?
Are you that jingoistic?


Freems have diesel engines too, MTU for The French and Isotta Frashcini for the italians. The ‘rafted isolated’ diesel engines are just most economic for low speeds


By that benchmark then Type 26 have diesels too…

I thought there was an ASW reason for T23, FREEM and T26 to have electric propulsion while T31 does not.
But strangely seems suddenly there is no difference…


T45 has ( famously) electric propulsion too. And what onboard ASW capability outside the helicopter does it have ?


Yes T45 have, but it was not setup for ASW.


Thanks for your usual high quality and insightful contribution.
Hull sonars have had a good rubbishing on here from some posters but it’s notable that we’re fitting them to the T26 so the RN must still see value to them although the US is moving in a different direction with the Constellation class


Its not ‘rubbishing’ , just no longer on the pedestal some seem to put them, and nowhere as good as the modern towed and variable depth units


Strangely the USN request was: have a sonar.
It did not specified if towed or hull, Which i found even more puzzling.


Not understand your point Duker.


Not a hull sonar is it .
Its not a ‘point’ …its a ‘tail’


Yes, i know. But USN did not made a request for a VDS, it said needs to have a sonar . I found lack of specification strange.


Excellent post.


Sonar….>mumble, mumble, mumble, mumble, um, mumble< 😉

Whatever the rights of wrongs of the situation in the Ukraine it has shown that FFBNW isn’t viable. Has never been viable. And if anything wastes money. Especially in a small fleet.

Firepower is important. EW may be clever. But……

I do like the base ship and its cousin the Absalon class. The USN should have ‘bought’ something like the IH instead of LCS.

Nothing to say really much more than that. Um. I do find the flags of the export customers designs oddly complimentary.

One day somebody here bands about the term GP will actually tell me what that means in the context of a hull without ASW and little to no firepower. The RN would be so much better if introduced a system of ‘rating’ for escorts. I would be much happier if the T31 was referred to as a ‘second rater’………

A PLAN Type 054 CODAD frigate for comparison.

comment image

Last edited 1 year ago by X

Cannot agree more think we should have a few Absalom’s cladd ships as they offer so much vetsitility they would probably meet most of the requirements of T 32 and LSS


LSS got quietly cancelled years ago. it was pre pandemic


Completely agree!


T31 may have emerged as a cheaper alternative to the highly specialised T26 but by choosing a proven, large and flexible design and a low-risk approach in choosing off the shelf systems it has enormous potential!

All depends on whether they can truly be built on time and on budget and whether the Royal Navy can then maximise their utility by ensuring the initial weapons/sensor fit is built on.

I’d be looking to ensure they have 24-32 Sea Ceptor and the Naval Strike Missile before trying to add MK.41 VLS.

Never quite understood the notion that because they aren’t as tailored to ASW as something like T23/T26 it means they’ll be useless in that respect. The Danish Iver Huitfeldt and Absalon classes run on diesels and have hull or towed array sonars!


I think that the T31 is intended to carry Wildcat as the T23 GP’s do. As you say, Wildcat has no ASW sensors at all

John Hartley

Shame the Wildcat did not get the foot longer cabin of the Lynx3/Westland 606 prototypes. Then more room for a compact dipping sonar.


Extra weight was the issue why no dipping sonar for a smaller helicopter like the Lynx/Wildcat which is a max weight 6 tonne chopper
The older SH-60B ( and Westland Seaking HAS.5) used by USN is a 10 tonne max weight, the Merlin is a 15 tonne max weight.

John Hartley

Well the Wildcat did get more powerful engines than the Lynx, & South Korea has fitted a compact dipping sonar to their Wildcat (+ NLOS missiles).


Sonar is possible for small helicopters. Lynx had them, AB-212(Italian UH-1N variant), etc.


Yes. Youre right.
Wildcat can have it too as the model for South Korea has the dipping sonar, shown retracted in pic, but it seems not for RN


Hi Peter,

As@Sunmack states, T31 will be carrying Wildcat, not Merlin. Not that it actually matters, as the ship cant que the helicopter onto a rough bearing of a SM if it doesnt have a sonar to do so!

ASW is a team game combing lots of different assets to make it truly effective, which having one/two Helos isnt.


Absolutely. The problem if the t31 has no sonar at all ( unlike the IH parent design) is a lack of any torpedo detection system. For a ship intended to operate on its own, this seems a dangerous omission.


The initial requirement was for the T31 to carry the SSTD system, which would give it the ability to detect torpedos, recommend manoeuvring options and automatically deploy decoys. SSTD uses a passive towed array, IIRC


If 32 cells of mk. 41 are fitted that gives so many options including up to 124 Ceptors, the limiting factor would then be stock not ship capacity?


Where is the space you put 32 mk.41 cells?


From the article:

“Type 31 will be built with the foundation structural seats for four 8-Cell Mk41 Strike-Length VLS modules. In light of justifiable accusations the surface fleet “acts like porcupines – well-defended herbivores with limited offensive capabilities”, the RN is known to be actively considering the addition of these 32 cells. Equipped with the FCASW/FOSW anti-ship/land attack missile, the T31 would gain a very significant increase in reach and firepower.“


Oh, so the idea is to replace the CAMM cells with MK41? there is space for that. For both i don’t think so.


32 mk41 or equivalent is 128 CAMM/CAMM-ER or ESSM (quad packed)

John Hartley

There is a youtube video at a trade fair, where the model T31 shows the various options. You can replace the forward 40mm Bofors with a SeaCeptor silo.


Instead of the mushroom farm, same place as IH


I’m wondering about the Anglo-Polish Future Common Missile, that’s supposed to be a medium range version of CAMM. Despite CAMM having a multi-domain targeting capability, I can’t see FCM replacing NSM, but if half the CAMM silos could cover anti-air out to 90km or whatever, it would be exceptionally useful to the LRGs.


There are not enough Merlin’s to go on the ships that actually require them.

John Hartley

Export customers have been offered an extended hangar, torpedo tubes & of course the air defence version based on Iver H. The SNA2023 exhibition showed Patriot PAC3 MSE fitted to MK41 launcher. A useful anti missile defence, I would have thought.


Cancel Type 32 and order more T31, even if its just a few. Give them all NSM, as it seems they are getting, bow sonar, and 24 Sea Ceptor. They then become the GP frigate we need. Add Mk41 VLS later if funds allow and after FC/ASW bears fruit.

Order some basic ships for drone operations. Commercial conversions if need be.


They all won’t get NSM the one in the Pacific may do or northern Atlantic but the rest will rely on seaceptor


Sea Ceptor is a self defense missile, not a strike one. Also, ther is enough sets to go around the fleet, with 11 sets of 8-pack lauchers being ordered for a bit over £200m
T45 , 6
T26 , not needed as FC/AWS
T23GP then subsequently T31 , 5

6+5=11 , and yes sets do have to be withdrawn for maintenance e.c.t but it is a thing fairly easily intergratable with the ships own port times.


25km is more than point defence. Thats for CIWS system, Sea ceptor is more of a ‘ local area defence’ compared to the standard large missiles and radars which would be ‘wide area defence’ of say 100km plus

Last edited 1 year ago by Duker

That’s why missiles like ESSM / CAMM-ER etc exist. There is a big gap between 100 & 25 km. It should be noted that RCN is treating CAMM as an extended range point defence missile (they already field ESSM).


No. Canada is treating CAMM as a short range system


No they are not. If CAMM really had an EFFECTIVE range of 25km they would not have paired it with ESSM, too much overlap. The absence of CIWS on the CSC and their description of CAMM as a “Close In Defence System”, pretty much confirms they view it as a PDMS.


Couple of questions:
I read somewhere that the Sea Ceptor cells from the T23s will be making their way over to these T31s. T23s have 32 cells, which are described on Wikipedia as a single 32-cell block (1×32). I know that Wiki isn’t always accurate, but I wonder why the RN wouldn’t simply transfer all the cells over, seeing as they may be in a single block anyway. The hulls are a 1 for 1 replacement, so find it hard to understand why they’d go with any less, unless there’s a space limitation?
Also, the article mentions Capability Insertion Points as part of the contract. Are at least some of these in place, or are they to be called off when the RN feel like it? The way I read the article, there may be a CIP planned for shortly after handover, so that additional equipment/capability can be added without affecting the core contract and price?


Hi Joe,

Just a thought on Sea Ceptor cells, looking at the diagram (not really clear) I wonder if 1×32 block impinges on the space for the Mk 41 cell fit? Just a thought, as looking at both the line drawing and photo doesnt make it clear as to how much space there actually is.

Then again, nothing to stop some quad packed Sea Cepror going into some of those Mk 41 tubes if required, cant see them all being equipped with offensive stuff!


That’s very true- the idea of packing 32 FC/ASW into those proposed Mk41 is a departure from reality! To be honest, aside from the greater flexibility, what use does T31 have for 32 Mk41 cells? The only reason I see it needing that many is if they remove the Sea Ceptor cells and use some of them for quad packing. What other munitions would they possibly carry in there?
Assuming that it won’t get cannister launched FC/ASW (makes more sense to me, frankly), I’d only really think a T31 would need 8 Mk41 cells, 16 at most. That would give 8 each AShM/land attack shots. That’s as many as a Burke is likely to carry, given that most of their cells are for air defence weapons. 2 packs of Mk41 for 16 cells, plus 32 Sea Ceptor must be cheaper than 8 pack of Mk41, and that would fit.
Just out of interest, found this image of a Hellenic Navy A140 with 32 Mk41. Assuming all is to scale, that would fit with 32 Sea Ceptor just fine.

Craig Lewell

I don’t know anything about engineering but there is a plan to up-gun/missile the Type 45’s with Sea Ceptor cells so the Sylver can be solely focused on the longer range variant of the Aster and ballistic missile defence Aster, so perhaps that’s why drawings have shown a reduction from 24 – 12 Sea Ceptor cells on the Type 31?

Last edited 1 year ago by Craig Lewell

Yes, I’d read about that too- you think that maybe some of the T23 Sea Ceptor cells are headed for the T45s instead of the T31s? Yeah, could well be- hadn’t thought of that.
Personally, I think the RN would be unwise to go for less than 24 from an optics perspective, but hard to know what they’ll do. They’ve been pretty hard headed about that stuff before.

Paul T

Sea Ceptor on the Type 23’s uses the original Sea Wolf VLS Tubes,they won’t be carried over to either the T45 or T31,the standard 6 Cell arrangement will be fitted.


Thanks, that makes sense to me now!

Paul T

The Sea Ceptor upgrade on the Type 45’s has nothing to do with the Sea Ceptor fitment on the Type 31 ,the spec for which was fixed and published some time before the T45 upgrade was announced.

Craig Lewell

Thanks Paul, very helpful ?


Pity none of the exports are uk built.

I appreciate that we have high costs, but if France, Spain, and Italy can build for export, then why not uk? Even more so now that having two competing yards should drive efficiencies.


Are the French and Italian yards building at a real profit for export or are there governments supporting them to keep them busy?
Relatively simple ships like the T31 can be built in lots of the countries that can afford to pay for them.

Trevor G

I do have serious questions about RN strategy as regards ASW. As discussed here and elsewhere, there is a growing threat to seabed infrastructure (energy and comms) in addition to more traditional submarine threats to shipping. Meanwhile we are building frigates and destroyers without meaningful organic ASW capability (T45 +T31). Plus, Wildcat has no dipping sonar and part of the Merlin fleet will be assigned to AEW duties. So it will rest on T26, nominally 8 but less SSBN protection and less those in refit/repair. Doesn’t leave much even before someone mentions Carrier Strike Group. Cutting T26 from 13 to 8 looks more and more like a serious error to me. Or am I missing something?


You are right, but build numbers are based on the idea of 8 x ASW Type 23, with 5 x General purpose Type 23, not sure what the main purpose was of the others we sold……. Ideally we .need 10 – 12 x Type 26 min with 8 x Gen purpose Type 31 fitted out with Mk41 vls and a sonar of some kind. These are lightly armed Combat Ships, and if the poo hits the fan, they’ll be needed to fight

Last edited 1 year ago by Paul42

You can guarantee that when the slimy stuff does hit the fan and a CSG is needed. The T31s will be part of the group. Primarily acting as a goalkeeper for the carrier and support ships. Adding another layer of defence between the carrier and T45s. Whilst the T23/26s are off hunting subs on the periphery.


It would help if the carrier itself actually had anything resembling self-defense capability other than a couple of R2D2s from the ’80s.


I am thinking that the Dragonfire system will have something to say about carrier defence before all is said and done.


The Problem is that the type 23s we’re built as anti submarine frigates then the 5gp frigates are just the same frigates without the towed array


As things are RN will have 8 Type 26 as ASW vessels if we assume 2 are maintenance, that means 6 operational.
I think it is ok to cover a CSG but there is 0(zero) for anything else and if there are losses things will get bad fast.

Last edited 1 year ago by AlexS

Hello Chaps…..Just want to put my own tiny view point on here if it’s OK ? ….. Any War is a game of numbers….always has been, always will be….. WW1. WW2 ….. Korea, Vietnam. Afganistan, Ukraine, ……… They are all just Wars of numbers…. Numbers of Humans killed for no proper reasons other than some Egotistical F**kwit’s own mindless thought process ………. Cheers Phill.


Mass production of manoeuvrable hypersonic missiles will make all sea vessels floating coffins.


Why do you believe that there’s something intrinsic about hypersonic speeds that make them particularly and instantaneously lethal to ships? And not just ships, but “all sea vessels”, presumably including submarines. Do you conclude we should cease building and using sea vessels? What about unmanned floating coffins, can we keep building those? Do you have any conclusions at all following from your unsupported hyperbole?

Even if there were no counter to hypersonic weapons (and there will be), did the development of nuclear weapons make all cities coffins and would you suggest we city dwellers sell up and live in a hole in the ground on Pitcairn?


Good points.
The navys have just made their self defence missiles reach out further to account for the faster speed of the incoming


Would a drone used to drop a sonar bouy screen be an effective replacement for the hull mounted sonar as it would not have the issue of a being mounted on a noisy ship? Although this may be limited by serviceability of the drone and weather conditions.


It’s a tad more complicated then just dropping a sonar bouy.

Firstly you need to qué the drone into the vicinity of the target. Then you need to drop a field of bouys some 4-8 are the norm (they have a short detection range). Then you need to get the information the buoys provide to whomever is going to decipher it and decide if it is a SM or not. Chances are the drone will have to drop multiple fields to detect and track a potential target. So, not a simple exercise.


Thanks, I was just thinking could this be a solution as it sounds better than nothing. not sure if the costs of sonar bouys would be prohibitive to appear over a large area, however the drone would in theory be able to provide the data link back to the ship.


It could work, but it is not something that will happen in 5 years or maybe more. Leonardo have a RN drone helicopter project in hands but what will be the results is to early to tell.


As @AlexS says, it is possible and I believe something the RN is working towards. Believe the intentions to get the drones to support the Merlin ASW aircraft, but as yet early days.


Type-31 is a gunboat. I welcome RN loving guns again after decades of missile fetish.
It is just suspicious it started after BAE bought Bofors.
Or BAE bought Bofors because RN started to love guns again?


As per Ukraine, perhaps with the future fighting environment being dominated by swarms of cheap drones, having a gun focused ship within your task group isn’t such a bad idea.


I have no disagreement as i said i welcome the choice.


There have been some posts stating that the guns won’t be radar guided but will rely on optronic guidance. I don’t know if anyone has any information on that?


Must be my questioning. I have not seen any radar director so i think the firing will be by optronic means.


It is not in the public domain it can be assumed the 57mm will be integrated into the TACTICOS CMS for control and be guided using the Mirador Mk2 EO cameras (Fwd mount on the pedestal below the foremast) and the NS110 primary radar.

a twofer


The radar give the data to the EO. But can only send data bursts in a bit less than 1 sec if its rpm are 60. An SSM moves 150m in 0.5 seconds, so hope that the optronic tracking works in bad weather when radar is not tracking the missile.

It is basically one more cost cutting.


T31 is definitely a gunboat, just not a particularly good one. More of a case of could have been / should have been.


Anyone know if the Sea Ceptor has ever been tested using supersonic targets, remember the 2017 trials with HMS Argyll and Westminster test firings at the Hebrides range at 2 km (safety zone) with the sub-sonic Leonardo Mirach target drone (max 200 m/sec ~Mach 0.6), eg thinking of something similar to the QinetiQ supersonic air launched “Rattler”target drone


Theres this new Australian developed supersonic target
The Grollo Evader is supposed to be priced at A$250k each ( pic, under wing)
The Sea ceptor itself reaches mach 3

The USN uses the GQM-163 Coyote at $4 mill each ( but might be used multiple times)


The French Navy during firing trials of their Aster’s 15 and 30 have successfully intercepted the Mach 2.5 GQM-163 Coyote, the last time was with the Horizon class Forbin AAW frigate at the Hebridge range during the NATO exercise Formidable Shield 2021.


RAN successfully tested ESSM against Coyote as part of their CEA radar upgrade back in 2013. Supersonic intercepts have been a thing for some time now. Hypersonic is now the question.


There were rumours of tests in Mediterranean with Israeli ballistic missile simulator targets of Sparrow family: Blue, Black or Silver. Might have included the Aster.

Barry Larking

The ‘development over time’ aspect of the T31 design is vital. I imagine this will build on the basic fitting out; much that can ‘plug in and play’. The real question is however, how many beyond current (and as always speculative) planned numbers? Also, R.N. recruitment and retention in the longer term.

Clueless Observer

Lots of negative comments on here, I have no/minimal knowledge of ASW, but if things went smelly, they could easily throw on a container with a self contained towed sensor surely ? These are GP frigates, I love the gun layout, ideal for Close air/surface which is what they are likely to meet during anti-piracy or in the gulf against drone. With NSM and sea ceptor we have a good star for a really flexible frigate, Mk41 and dragonfire or the like in the future will make these really useful.
What do we want? A handful of top spec ships or a larger mixed fleet? Wish the RAF would go this route, not every conflict or role needs 6th gen aircraft, they also need need a larger fleet !


There is so much in this article I disagree with. Bow mounted sonar was essential (but is missing). Bofors 57mm is not a frigate gun. Absolutely no NGFS which, especially in the littoral is essential. Don’t bother operating in places like the Pacific if you can’t. USN can get away with it with 16 NSM & backup AB Destroyers. RN – not so lucky. They thought ((USN) that they could get away with just the 57mm on the Littoral combat class idea. Not possible.

T31, currently no AShM. Second grade radar at best. (Thales happy to supply better). No longer ranged AA missiles (CAM is good but limited – CAMM-ER or ESSM at least). Why weren’t the engines etc raft mounted? There is FFBNW & NFF. A140 is a good GP frigate design. Australia & NZ may end up building it as an Anzac replacement (for the same reason UK is building T31). T31 barely a frigate – really an oversized OPV.

I get why. Building to a budget. However T31 has been so hamstrung as to be close to pointless. Choices have been made that are next to impossible to rectify without spending even (much) more money. FFBNW should mean you only need to add the FFBNW components, not rip stuff out. Not impressed at all.

A140 is winning export contracts. T31?


Theres ‘bow’ and theres under hull sonar
B3 Type 22 had a bow sonar, the earlier ships had ‘under hull’ version

The T26 will have a bow sonar like the T23 but the T45 is under hull


Type 31 platform will be superior to many overseas competitors and the RN’s legacy Type 23.
Too noisy to use Towed Array effectively
No hull sonar
SSM that will scratch a surface opponent not sink it
I doubt a Russian destroyer or sub skipper will lose any sleep over facing this oversize OPV
Undergunned in a fight and too slow to run.Jackie Fisher will be rolling over in his grave.

Paul Burch

Has anyone mentioned the fact that 5 of the type 23’s are not equipped with towed sonar and are considered general purpose frigates. It seems to me that these economical ships are quite capable of deterring those that would harm our interests in most situations. So against an Iranian frigate or even most Russian surface vessels she would be more than capable of looking after herself. Could she defend herself against a submarine threat? I suspect she could but not so easily hunt one. So the alternative is 2 more type 26 or 5 more type 31. Quantity, as they say, has a quality all of its own. It seems a smart choice. Hulls in the water to deter. High end quality available to fight. Consider the actions the RN has been involved in since the end of the Second World War? Would these ships cope with a modern day encounter with any of those threats? Argentina? Iraq? Serbia? Iceland? Suez? Yes, no doubt. And I’m pretty sure, if equipped with sufficient Sea Ceptors, they’d cope with Russia and China too. Saying we don’t need General Purpose Frigates, but only ASW Frigates, is a bit narrow a view of the world.

Paul T

The GP Type 23’s have the luxury of a Bow Sonar ,so even without a TAS they are still useful ASW Ships,the Type 31’s dont have that luxury,short of using an embarked Merlin their Submarine options are very limited.

Clueless Observer

Well said, I think the RN has made a top decision with T31, 5 x hulls in the water before the T26 fleet is completed and nearly for the same price as one and a half T26. When and where would extra T26 be made ?
T31 will come online with basic abilities but has a lot of space for other kit to be added through its lifetime.
Mk41 VLS, NSM etc.
If the poop hits the fan it’s easier to bring a hull in and upgrade or add kit than it is to build an entire ship.
Lets have T32 as a follow on with a full load of VLS cells and larger main gun plus a small well deck ?
We need a larger fleet !


The claim about T31s far superiour build standard compared to the Iver Huitfeldt Parent design is not only patently false but also dishonest. While classification standards evolve over time , and T31 benefits from over a decade of changes since IH was built , the implication that the danish vessel was built to a substantially lesser standard is mistaken.

It wasnt just built to DNVs civilian standards as the article implies but to DNVs NAVAL code AND to NATOs naval standards(STANAGS). As such , at the time of build ca 2010, it fully lived up to the then accepted warship standards includings Lloyds ,wrt to compartmentalisation,watertight subdivision, structural strength, damaged stability, redundancy, shock proofing , signature reduction ( for an AAW frigate) ,armor protection, magasine protection etc .

The further claim that T31 internal design has been substantially changed and improved is also wrong, there are in fact no major changes to the internal and superstructure design aside from the altered bridge (open wings), mast and boat hangars. This is also evidenced by the very low cost of T31….had the original danish design required the significant modifications claimed, it could simply not have been built for £250M , and would furthermore have been heavier than the Iver Huitfeldt class, which it also isnt.

It is a shame that an otherwise excellent and interesting article is marred by what can only be described as a bad case of “british exceptionalism “.




The T31’s are not destroyers. They are frigates, and pretty sizable ones at that. There is plenty of space and spare tonnage for a number of additional weapons and other upgrades, and to my Mark I American eyeball, they will be quite capable if and when they are ever fully equipped.

They also come at a very “reasonable” price point. The RN could readily solve its hull shortage by building at least one more 5 ship batch of these vessels. If it were up to me it would be two batches totaling ten more, plus substantial sales for export.

No, they’re not the T26. But while it would be marvelous to get at least another pair of those ships as well, I don’t think that is going to happen. Meanwhile the T31 is perfectly fine for what it is.

Last edited 1 year ago by Will

This ^^^^ is quite clearly the way forward. I never understood why the RN was trying to build still another clean sheet design when it is so strapped for cash. Alright, so maybe the Admiralty wanted some motherships for hosting mine clearance UUVs and helos. Do you need a brand new frigate design for that, or could you just build more T31’s and make them a specialist sub-class?

My 2 cents is that you don’t even really need purpose built warships for anti-mine warfare. Just reconfigure a handful of sizable cargo vessels, build an Erector Set flight deck and hangar for 3 helos and some UAVs, load some UUVs on the weather deck, and away you go.

That’s basically what the USN is doing with the Alaska class oil tanker conversions, which were designed originally for British Petroleum or so I have read.

Last edited 1 year ago by Will

These aren’t as cheap as you think. Each one is almost $800M.


These are dirt cheap and it would make sense to order 1 a year ad infinitum. That way you have a stockpile of hulls for sale and a reserve of escorts in case you need them. Why dont we store laid up ships in drydock? We have plenty to spare. This is the way to build the Navy we need for the 21st century!


To see what the T31 could and should be just look to the Polish model.
I can see the reason not having the 5″. But if considered useful put 5″ where the 57 is, with the 57 in place of the fwd 40.
The ship design showed it can mount more 40’s at serval positions (including 1 either side of the 57 and slightly aft) so if a second 40 (or two) is considered needed it could still be fitted.
The 4 module mk41 should be fitted from the off. At the minimum would give the option of 128 camm if nothing else ever procured to go in them.
I’d suggest a base mounting a dozen (in XSL? or scabbed on) camm on each the funnels (leading faces) (24 total) and possibly more else where to give a close in air defence with out having to use the 41 space. A less capable (expensive) containerized towed array could be added in mission bay, paired with bouys dropped by the helicopter and UAVs. (it could be the similar mini TA that could be fitted to a pair of USVs in place of 2 of the boats allowing a wide coverage in conjunction with the ship. 8 deck NSM (in front mk41 space) with 16 ideally. The mk41 could be used for any other mix of SAM, SSM (longer range), need to the mission. As others have said some ‘drone’ launchers should also be considered (swith blade 600 etc.) -maybe aft next to hanger or forward behind the 57 and below the 40 (current fit), a 2 to 3 dozen as a base. Would make a much more capable ship.


Type 31’s built for political & civil service aims & ambitions < wade through the jargon & you’ll find type 31’s will have the facilities to undertake Disaster / humanitarian relief & aid operations globally , should be enough said , also has an hanger for medium range helicopter so how come landing platform capable of operating Chinook size helicopter , mind boggling ,57 mm multi purpose cannon < Yes it’s a Cannon , inifectual against any target that is’ent light weight , limited range in surface & land based targets , 40 mm ciws x 2, why ? , common sense would say just put 2 57 mm multi purpose guns onboard , do same job but slightly better , No anti ship / submarine capability other than helicopter , limited air defence ( 24 sea ceptor cells , RN adopted a single cell missile fitment for sea ceptor <T23-T26-T45) , fitted for/space for – never happens , & yes T45 having sea ceptor fitted forward of sea viper , cheaper maintanance than sea viper , like to know what they intend to fit in the 24 , now spare launchers – maybe extra 8 or more long range sea viper’s or just empty just like Mk 41’s on T26 frigates .


Isn’t it amazing what can be done in a relatively short time once the Government are made to realise that their interference will result in the Royal Navy only having half a dozen fully operational frigates in less than ten years from now!


I generally like these platforms, particularly their flexibility. I would add a hull-mounted sonar (as per the original design), replace the aft 40mm with a SeaRAM launcher, add 2 25-30-mm mounts P/S, and enlarge the hangar so it can accommodate 2 medium helicopters and/or UAVs (as per the original Absalon class).

One of the features I appreciate the most is the Complement of 80–100 but accommodation for up to 160. This allows it to carry a platoon or 2 of marines or special forces, again enhancing the flexibility of these ships. Also, it shouldn’t be hard to integrate electric drive on future flights of this design.

Luke Barnes

I know this is an older article….. but I come for the comments. We have people claiming that US missiles are garbage because US doctrine is to fire two. Must be crap since the UK only fires one. Couldn’t be that the nation with the largest military budget in history both knows that it increases odds and has the VLS capacity to do so. Let’s see….. ESSM is garbage, despite it grabbing at least double the range of sea Ceptor. The constellation costs way more that t-31, but because US missiles are garbage, it really isn’t that much more effective.

We have people saying type 31 is garbage since it doesn’t have integral ASW as its priority. Yet the UK is testing a thin line towed array on a USV that along with its helo would provide ASW capability in a meaningful way.

We have someone saying that mk41 isn’t the best VLS choice despite having more weapons in service and testing than any other VLS.

It just amazes me that we have half the info and constantly assume we know more than ministers with way more info than us.