| Summary : Remains of 1918 wreck of German Type UB II submarine, positively identified by a propeller with the ID stamp, its location, and evidence of war damage. The UB-31 is located approximately 3 miles SSW of Folkestone, which foundered after being depth-charged, in turn detonating a mine, while on a war patrol in the Straits of Dover operating out of Zeebrugge.
Constructed of metal in 1915 and commissioned in 1916, she was powered by diesel engines and electric motors. The UB-31 was part of the Baltic Flotilla which took part in 25 patrols, sinking 27 merchant vesselsm including Scottish ocean liner RMS MEDINA (832166), and British steamer WAIKAWA (832179). Another site was formerly attributed to the UB-31 but is now regarded as the possible remains of UB-109 [see 901790].
The site of UB-31 has been designated as a Protected Place under the Protection of Military Remains Act 1986, under Statutory Instrument 2019 No.1191.
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| More information : Wreck Site and Archaeological Remains:
Vertical Datum: LAT (1)(3)(5)
Orientation: 155/335 (1); 090/270 (3)
Quality of Depth: swept by wire drag (3)
Sunk by drifters in Dover Straits. (Der Krieg zur See)
07-NOV-1961: depth 61ft in general depth 74ft. (1)(5)
18-OCT-1977: In 51 02 03N, 001 10 17E; depth 17.3m in general depth 22m, scour 23m, height 5.3m, length 41m. Lies 155/335 degrees. (1)(5)
24-JUN-1986: Dived on in 1985. Wreck of submarine, lying with list to port. Mostly intact but with large hole in hull forward of gun, which is forward of conning tower. Believed to be wreck of UB 31. (1)(5)
22-JAN-1997: Examined in 1996 in 51 02.04N 001 10.31E (WGS 84). Swept clear 16.4m, foul 16.7m. Least echosounder depth 16.6m in general depth 21m. No scour. DCS3 height 4.5m. Length 38m, width 30m. Lies 090/270 degrees, intact. (5)
She now lies at 51 02.03N, 01 10.17E and is intact apart from a large hole in the hull forward of her conning tower, caused by a depth charge. (2)
Charted as UB-31 (POSSIBLY) in 21m general depth; dimensions of site 38m x 30m. (3)
Located approximately 3 miles SSW of Folkestone. (4)
This wreck has been identified as the remains of a German UBII-class submarine, with hull blast damage consistent with loss to contemporary war causes. It is believed to be the remains of UB 31, although this identification has not been confirmed. The location of the visible blast damage is inconsistent with the naval intelligence reports of 1918, casting some doubt on the identification. The other principal candidates for the identity of this submarine are UB 33, UB 38 and UB 39. UB 29 and UB 32 are also considered possible, although less likely, candidates.
It is a coherent wreck site with severe structural damage visible on the starboard side forward, virtually splitting the hull in two, and consistent with blast damage, a characteristic manner of loss for this type of vessel during its period of operation (whether caused by mine or depth charge). It is estimated that approximately 60-75% of the structure survives. (7)
This site has been assessed under the Protection of Wrecks Act 1973 for the historical, archaeological or artistic importance of the vessel, or of any objects contained or formerly contained in it which may be lying on the sea bed in or near the wreck. The site currently does not meet the criteria for protection. It is not protected under the Protection of Wrecks Act 1973. (6)(7)
20.7.2016: Wreck examined in 5102.078N, 0110.202E [WGD]. Least depth 16.459m in general depth 19m, length 33.3m, width 4.3m, height 4.6m, orientation 162/342 degrees. Wreck is mainly intact. (5)
This wreck site is labelled by UKHO as 'UB 31 ?' (5). Identitiy confirmed as UB 31 by Innes McCartney. (8) Content from Casualty record (1490040) has therefore been moved to this, the Site record, for UB 31 (901777). (8)
Key features of the archaeological remains include the forward torpedo tubes; the starboard side pressure hull just aft of the hydroplane which is heavily crumpled from underneath; the explosive damage hole which is mainly confined to the starboard side, but the submarine was almost split in two, as damage can be seen on the port side as well. The conning tower hatch is shut, and the single periscope mount is of the type associated with the UBII-Class. The muzzle of the deck gun points skyward. The engine room hatch is shut. The outer skin around the stern has fallen off, revealing the pressure hull. This looks more likely to have been caused by recent corrosion more than incident damage. The propellers have been removed from the wreck, leaving just the shaft. (8)
At least one of the propellers is reported to have been stamped "UB31". The site was surveyed by Innes McCartney on 25 April 2011. (9) No further information regarding the whereabouts of the propellers have been found by McCartney. (8)
Wessex Archaeology was commissioned by English Heritage (EH) to undertake an Undesignated Site Assessment of the possible wreck site of UB-31, lost off Folkestone on 2nd May 1918. The assessment of the site was undertaken as part of a two stage investigation. Stage one consisted of a geophysical survey and stage two consisted of a diver survey of the site. The geophysical survey aimed to locate the wreck and inform the diving investigation, whilst the diving investigation resulted in a video survey of the wreck site. The survey informed an assessment of the current state and condition of the submarine and the identification of prominent features. The assessment confirmed the identification of the wreck off Folkestone as an example of the German submarine type UB II and circumstantial evidence supports its identification as the Uboat UB-31. The site has been assessed against non-statutory criteria for scheduling and has not been recommended for designation. The boat was observed as being in good condition with the pressure hull complete abaft the conning tower but damaged by the explosion that sunk it forward of the deck gun. The two propellers are missing. (10)
The site of UB-31 has been designated as a Protected Place under the Protection of Military Remains Act 1986, Statutory Instrument 2019 No.1191. (12)
Wreck Event and Documentary Evidence:
Type UB II submarine.
02-MAY-1918: Sunk by mine in the Straits of Dover at 51 01N 001 16E, with the loss of all hands. (1)
'During 1918, the Dover barrage was the grave of the following thirteen U-boats, most of them being forced to dive into the minefield and being blown up after sighting British patrol craft . . .
'UB-31. Depth charges of drifters . . . May 2.' (2)
'After being away from base for 16 days on a war patrol, UB-31 attempted to pass through the Dover Barrier in daylight. Their periscope was sighted by the Admiralty drifter LORD LEITRIM, which depth-charged the enemy vessel. A second Admiralty drifter, the LOYAL FRIEND, joined in the hunt, assisted by the Royal Navy airship SSZ-29 and a third drifter, the OCEAN ROAMER, which added her depth-charges to those already dropped. The last pattern of charges dropped detonated a moored contact mine underwater, which destroyed the submarine and all her crew.' (3)
02-MAY-1918: Mined and sunk in the Straits of Dover, in position 51 01N 001 16W, with the loss of all 26 hands. It is remarked that UB-31's loss may be interchangeable with UC-78's, since both were lost on the same day in the same area, one being attacked by drifters as in (3) above, the other being mined near Le Colbart. (4)
[UC-78's date of loss given as 09-MAY-1918 and position as west of Cherbourg on Uboat.net as at 07-MAR-2012.]
'UB31 departed for its last patrol in the Channel on 16 April 1918. This was unknown to Room 40 (National Archives ADM 137/3916). The 1919 List states that UB31 was destroyed on 2 May 1918 at 51 01.20 01 16.10E (seconds) (ADM 239/26). This position is 3.8 nautical miles from the wreck. - - - The site of the oil rising from the action was buoyed and then most probably fixed. The action itself resulted in two drifters, OCEAN ROAMER and LORD LEITRIM, sighting a periscope, dropping a depth-charge and then being guided to a patch of oil by an airship. Another depth-charge was dropped and the site buoyed (NA ADM 137/2097, 312-324).' This is almost right on top of the wreck of UB78. For further details, see Source (8).
Launched: 16-NOV-1915 (1)
Commissioned: 24-MAR-1916 (1)
Builder: Blohm & Voss (1)(3)
Where Built: Hamburg (1)(3)
Propulsion: Screw-driven oil engine (3)
HP: 142 (3)
Armament: 2 bow torpedo tubes; 1 x 5cm gun (3)
Unit: Flandern Flotilla (1)
Commanding Officer: Wilhelm Braun (1); Oberleutnant W Braun (3); Oberleutnant zur See der Reserve W Braun (4)(11)
Crew: 22 (3); 26 (1)(4)
Crew Lost: 22 (3); 26 (1)(4)
Owner: Kaiserliche Marine / Imperial German Navy [all sources]
Date of Loss Qualifier: Actual date of loss
Additional sources cited in Shipwreck Index of the British Isles:
TUB p332; SUB p10; BUB p139
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