Whilst undertaking detailed seabed scanning for the development of windfarm projects in the East Anglia Zone, off the coast of Norfolk and Suffolk, windfarm developers ScottishPower Renewables (SPR) and Vattenfall uncovered something they weren’t expecting – an ‘uncharted’ wreck of a WWI German submarine, missing in action since 1915.

Charlie Jordan, ScottishPower Renewables’ project director for the East Anglia ONE windfarm says of the discovery: “The scanning team were expecting to see wrecks, but such a discovery was quite a surprise and has been extremely interesting.”

SPR and Vattenfall used advanced sonar technology to scan over 6,000km2 of the seabed in the Southern North Sea over two years, which is nearly 4 times the size of Greater London (1,583km2). This work is critical to understand seabed conditions, and allow the companies to design the layout of their proposed projects. Although more than 60 wrecks were discovered during the scanning work, most of these were anticipated, but the uncharted submarine 90km from shore was entirely unexpected.

Image Credit: http://militaryhistory.x10.mx Sakhal 2012-2016

Andy Paine, Vattenfall project director of East Anglia Offshore Wind Farm comments: “Following the discovery the team reported its findings to the relevant authorities, including RoW (Receiver of Wreck) in the UK. The seabed scanning had been undertaken by Netherlands-owned company Fugro, and their team made us aware of the Dutch Navy’s hunt for its last remaining missing WWII submarine.

“We were all extremely keen to make contact with the Dutch Navy to see if this could be the submarine they have been looking for over so many years: could we at last have solved the mystery?”

The Royal Netherlands Navy was duly notified to investigate whether it was Dutch military submarine HNLMS O13, which went missing in action in June 1940, after the crew were tasked to patrol the waters between Denmark and Norway.

The wreck discovered within the East Anglia Zone is 57.6 meters in length, 4.1 meters in width and 4.6 meters in height and the bow appears to be facing south. Damage was observed at the bow and the stern, so the original length could be slightly longer than it appears and debris surrounding the wreck suggests a more likely length of over 60 meters (but less than 70m). GoPro footage taken by the Dutch Navy divers highlighted clear images of the conning tower and deck lay-out, which suggested the wreck was of German origin. From German drawings it was identified that this was a WWI German submarine: Type U-31. A database of reference books shows that only U-boats U-31 and U-34 had been lost in this area of the North Sea.

Commander (Retired) Jouke Spoelstra of the RNLNavy/Submarine Service, who heads up project ‘Search for O-13’ adds: “Whilst it was disappointing from our perspective when we realized the wreck was not that of O-13, we conducted several dives with divers of the minehunter HNLMS Makkum and with a REMUS UAV sonar team with the aim to achieve clearer footage of the wreck and undertake investigative work to ascertain its identity. It wasn’t an easy job and several dives were required before any real progress was made due to the sea conditions surrounding the site meaning we couldn’t obtain any evidence revealing the exact identity. Fortunately on a recent dive undertaken by the Lamlash North Sea Diving team they had good conditions and so were able to achieve clear footage and finally identify the wreck.”

Three years after its initial discovery (in September 2012) the wreck was officially identified as German submarine, U-31, which left for patrol on 13 January 1915 never to return. The wreck is approximately 90km offshore in the North Sea but sits on the seabed at a depth of only 30 meters.

Mark Dunkley, marine archaeologist at Historic England adds: “SM U-31 was commissioned into the Imperial German Navy in September 1914. On 13th January 1915, the U-31 slipped its mooring and sailed north-west from Wilhelmshaven for a routine patrol and disappeared. It is thought that U-31 had struck a mine off England’s east coast and sank with the loss of its entire complement of 4 officers, 31 men.”

“U-31 was the first of eleven Type U-31* submarines built between 1912 and 1915. The class were considered very good high sea boats with good surface steering; 8 were sunk during operations while 3 surrendered and were scrapped after the war. Of those lost during operations, the whereabouts and fate of two, including U-31, was unknown.

“The discovery and identification of SM U-31 by ScottishPower Renewables and Vattenfall, lying some 91km east of Caister-on-Sea, Norfolk, is a significant achievement. After being on the seabed for over a century, the submarine appears to be in a remarkable condition with the conning tower present and the bows partially buried.

“Relatives and descendants of those lost in the U-31 may now take some comfort in knowing the final resting place of the crew and the discovery serves as a poignant reminder of all those lost at sea, on land and in the air during the First World War.”

ScottishPower Renewables’ Charlie Jordan concludes: “Unravelling the whole story behind the submarine has been fascinating and it’s heartening to know that the discovery will provide closure to relatives and descendants of the submariners lost who may have always wondered what had happened to their loved ones.”

As an official military maritime grave, the wreck of U-31 will remain in its final resting place and plans for any offshore windfarm development will be progressed ensuring no disturbance to the area.

*There were 11 Type U-31 submarines built, titled U-31 to U-41.

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