Midget submarine identification

Do we have any midget submarine experts here? I've been staring at this image for so long that I think I'm starting to go cross-eyed, let alone projecting my own 'desires' onto it:

© IWM A 29730



This is taken at the Underwater Explosives Department (I've seen it abbreviated to both UNDEX and UDEX) on 19 July 1945.

My eye of course goes to the midget submarine in the background -- and my frustration goes towards those workers in front of it for partially blocking the view!

The prototype X-3 and X-4 boats, a handful of the X-20 class and the XT training subs were passed on to UNDEX towards the end of the war so they could play at various imaginative ways of crushing them. The letter initiating this handover was sent out on 31 May 1945, so before the date of this photo.

But of course it could be an Italian/German/other sub that has been 'acquired'.

This is where my desires start clouding my judgement, layering on top of my own not-exactly-extensive knowledge.

Stern section
To me, this looks like the stern of an X-20 series X-craft - the rudder and hydroplane arrangement is fairly distinctive? I've done so much staring at this 3D model by Wessex Archaeology, too - again, this makes me think that the general shape is like that of an X-20 series X-craft.

The big difference, to my prejudiced eye, is the propeller guard, which is noticeable compared with the struts that were usually in this position.

This is where my bias comes in, as one of the modifications requested for X-20 and X-23 ahead of D-Day reconnaissance was the installation of a propeller guard - Admiralty responded to COPP's request by saying it would be passed on to Broadbent's and Markham's, who were building them. The possibility that this might be X-20 or X-23 makes me excited in ways that I really shouldn't admit to in public.

Bow section
But to my eye the bow section looks nothing like an X-20 craft/XT-craft, nor an XE-craft. Judging by the proportions, I'd expect the 'step' of an X-20 class/XT craft to be visible. And the XE-craft (which seemingly weren't handed to UNDEX at this stage) have a fairly distinctive 'droop' to the bow.

The bow also seems too rounded at the bow compared with an X-craft.

It also seems to have a bilge keel?

I guess it could be X-3 or X-4?

But my main question is: is it obviously identifiable as an Italian/German/other sub?

Fingers crossed someone may be able to offer some insight!

 

Hello Rob,

I am not the expert, but this could be the story about the submarine in the background of the photo.

Aberlady Bay’s midget submarines – Awesome Aberlady

http://www.aberladyheritage.com/wp-...erlady-Bay-Summary-Report-Alison-Boutland.pdf



[unknown] X-craft: Aberlady Bay, Firth Of Forth | Canmore

Best regards

Finn Buch

 

Back in 1987 D K Brown RCNC wrote a series of articles for Warship (then published quarterly) about the postwar RN ships trials.

In 1943 the Admiralty set up the Admiralty Undex Works, a title soon replaced by Naval Construction Research Establishment (the original title was changed when too many people associated it with underwear manufacture!!!). This was based at Rosyth on the River Forth (east coast of Scotland). This organisation began work immediately and some trials were run through to the end of the war. On 29 Oct 1945 approval was given to set up the Ship Target Trials Committee to recommend priorities and list the trials required against certain ships. There were various sub-committees including a number under the chairmanship of senior officials at the NRCE. Due to postwar steel shortages, the loss of trials ships was to be avoided. Apparently shipbuilders hung around the trials like vultures with quantities of whisky on hand to bribe those in charge to let them have first crack at salvaging & scrapping individual ships. The trials themselves took place in Loch Striven on the west coast of Scotland.

Trials against submarines were covered in Warship 43 published in July 1987.

There were 16 trials against 9 midget subs of the X & XT classes. These trials were early in the programme as conclusions were able to be drawn from them before moving on to larger subs. It was not generally possible to identify which craft were used in which trial, but the following is known.

Trials started in March 1947 with the target hung over the bows of the Boom Defence Vessel Barfoot.. The first trials were against the experimental craft X3 & X4 to set the test parameters (note these do not appear to have been scrapped in 1945 as stated on Wiki). The next sequence was against various craft including X3, X4, 3 of the XT1-4 class & 1 of the X5 design. These were hung at depths ranging from 15-450 ft. The next sequence was against XT5 class craft. One XT craft was lowered to collapse depth.

Craft from the X5-10 group are noted as having been usedd, but as these were all lost in WW2, DKB believed it was a reference to the X20-25 group, and with X22 (lost in WW2) & X24 (museum ship) accounted for that only leaves X20,21,23 & 25 as being possibly involved in the trials.

The X & XT craft were considered expendable since it was only intended to retain the XE craft postwar. None of these were involved in the above trials. The identity of the XE craft at Aberlady Bay remains unknown AFAIK. 11 XE craft were built in WW2 (1 scapped incomplete XE10) (with another 4 in the 1950s as the Stickleback class). XE1-6 were scrapped in Australia in 1945/46 having been on the depot ship Bonaventure in the BPF. XE8 is in a museum. So in theory they must come from XE7,9,11 & 12.

Turning to the photo in the opening post, the most unusual thing for me is the propellor shroud, which I've not seen before. None of the (few) photos in the Warship article show anything like it. As for the bow I think there is one explanation that makes sense, at least to me. When in dock these craft didn't rest on their keels. There was always a supporting structure on which they sat. For example X5 on Bonaventure.



Another X craft on Bonaventure



Looking at the photo in the opening post there seems to be a "plate" sweeping up under the near side of the bow. Could it be a support while the craft is ashore? It is not like those fitted to Bonaventure, but does it have to be? The Dockyard was perfectly capable of cobbling something suitable together to suit its needs. Take that away and the bow very much looks like an X/XT/XE craft.

 

Yes, they're definitely connected to the trials - although these particular two were I think handed over for the RAF to have a pop at, rather than attempts being made to crush/destroy using underwater charges/depth pressure. I really want to get up to Aberlady Bay at some point. Wessex Archaeology did quite a bit of probing of these wrecks during the main Covid period and produced some amazing 3D scans, too:

Western Aberlady Bay wreck 3D scan

Eastern Aberlady Bay wreck 3D scan

Apparently these two were XT-craft, built for training. The Nautical Archaeology Society couldn't determine which two exactly, but were able to rule out XT-5 which was apparently slightly longer due to modifications made during its pre-trials service.

Summary report (PDF)

 

The National Museum of the Royal Navy has some letters exchanged by Richard Compton-Hall, former director of the Submarine Museum, in the 1980s. (Archive reference RNSM A1979-22). He and his correspondents also struggled for definite identiies, but did include:

• XE-7: placed into immediate reserve with 5th Submarine Flotilla - "scrapped about 1951".
• XE-8: placed into immediate reserve with 5th Submarine Flotilla, used in Above Us The Waves, officially scrapped 1953, used as an underwater target near Portland until early 1970s, later raised [and now at Chatham Dockyard].
• XE9: placed into immediate reserve with 5th Submarine Flotilla - "scrapped 1955". I've seen suggestions elsewhere it was later sunk as a target, too.
• XE-10: construction cancelled at end of war - some machinery and equipment retained as spares
• XE-11: sunk following a collision during exercises in Loch Striven in March 1945, was raised but repairs were cancelled towards the end of the war
• XE-12: placed into immediate reserve with 5th Submarine Flotilla - "handed over for scrap on 16 December 1953". Have seen a suggestion elsewhere it was cannibalised for spares in 1952 for spares

Regarding the trials, they (tentatively!) suggest:

Trial 1: X-3
Trial 2: XT-2, XT-3 or XT-4
Trial 3: X-4
Trial 4: one of the X-20 class
Trial 5: XT-1
Trial 6: XT-2, XT-3 or XT-4

via Brown: "The next sequence was against various craft including X3, X4, 3 of the XT1-4 class & 1 of the X5 design"
That seems to match the above (assuming the first tests on X-3 and X-4 to establish parameters weren't given a number)?

via Brown again: "The next sequence was against XT5 class craft. One XT craft was lowered to collapse depth."
Again, that broadly matches the following?

Trial 7: XT-5
Trial 8: XT-6
Trial 9: one of the X-20 class
Crush test: XT-2, XT-3 or XT-4

Thing is, I think that 'uses up' all the XT craft that were built? So which two are at Aberlady Bay (or was the trial there included in the numbering that Compton-Hall et al came up with)?

One possibility, which they warn about, is that XT-7 to XT-19 were apparently on order at the end of the war - these were cancelled - but if some were in an initial stage of production, were their hulls handed over for trials in an "as is" state, too?

(My head hurts.)

 

Thanks for the info from Brown's article.

I hadn't even considered that it might be a cradle for the X-craft - which is pretty stupid of me because they obviously needed one. Hmmmm ... Food for thought - thank you!

re: the propeller shroud - this is what intrigues me because COPP requested a 'propeller guard' for X-20 and X-23 so they could do beach reconnaissance of Normandy - the method was to go in at periscope depth using the echo sounder until they grounded on the sand, so I guess they may have wanted to give the propeller extra protection. (They did it on a rising tide so that they could float off again!)

The request was sent through to Broadbent's and Markham's, which build X-20 and X-23 respectively, while they were under construction - so such a guard/shroud could easily have been integrated into the subs during construction - this one does seem to be fairly integral.

The other thing I wondered, just from looking at photos, is whether it might be a German Seehund - but I think not - the guard looks similar but other elements, to my eye, don't fit.

 

The Seehund crossed my mind as well but it can't be. In the Seehund the propellor shroud and rudder are part of the one unit. In your photo we have a propellor shroud with a separate rudder aft of it. Seehund for comparison.

 

A little background info. From The Coastal Command Review. Vol.IV

 

I've just been going through the 'monthly letters' sent by the commander of the 5th Submarine Flotilla, based at Fort Blockhouse in Portsmouth, covering the period at the end of the war. (Held in the archive at the National Museum of the Royal Navy, reference RNSM A1944-6)

If that is an X-craft in the photo, if that propeller guard suggests it's either X-20 or X-23 with its COPP-requested modification showing, and if the date of the IWM photo (July 1945) is correct ... I think this is X-23.

The following extracts suggest X-20 only arrived at UNDEX in September/early October 1945, and that X-23 wasn't lurking around in Portsmouth at any point.

----------------------------------

March 1945: "...four X-20 craft are being laid up in reserve. Two have arrived and two are expected shortly."

April 1945: "X-20, 21, 24 and 25 are in a state of care and maintenance at Fort Blockhouse and will shortly be brought to produce with the exception of X-24, which will be mounted in Fort Blockhouse as an exhibit."

June 1945: "Most of the X-craft have been stripped and are now waiting transport to Rosyth where they are to be broken up."

August 1945: "Two XT craft and one X-craft were sent by rail to UNDEX. X-24 has been placed in cradles at the main gate where it will remain for ever."

September 1945: "On September 17th X-20 was despatched to Liverpool to take part in Liverpool Thanksgiving Week, after which she was despatched to UNDEX in Rosyth."

 

I posted a similar query on Twitter and got one reply that chimed with a growing suspicion of my own: that the bow and the stern may be different subs. The bow may be a little bit closer, with the stern behind it?

Anyway, if it is X-23, I thought people might be mildly amused to know that 80 years ago was the first time it wet its keel:

https://twitter.com/copp_survey/status/1735044853590057027?t=bTZ8ikgx0jV_nXMqlWaviA&s=19