Dundee divers nail U-boat’s last act of defiance

After more than a century at the bottom of the North Sea, the truth about the sinking of a notorious World War One U-boat has emerged, thanks to a team of scuba divers and 3D wreck-modellers.

Although UC-71  went into action only in November 1916, the German submarine was responsible for sinking no fewer than 61 Allied commercial vessels in the North Sea in the course of 19 patrols, using both torpedoes and mines. 

Questions remained about the circumstances of the U-boat’s own sinking after the end of the war, however, with interest revived recently by publication of an engineer’s diary entry stating: “No Englishman should step on the boat. That was the will of the crew, and they achieved it“. 

Two University of Dundee professors and scuba divers, Chris Rowland, a 3D visualisation of underwater environments expert at Duncan of Jordanstone College of Art & Design, and communication design expert Kari Hyttinen, now believe they can confirm that UC-71 was scuttled.

“Hatches are certainly open across the submarine, which corroborates the claim that it was deliberately sunk,” says Prof Rowland. “It is possible, however, that divers may have visited the wreck before it was protected. Indeed, it is highly likely that divers may even have been inside the sub, though this would be exceptionally dangerous.

“But, given what we know and from the physical evidence witnessed when we were down there and from our imagery, it is likely that the boat was sunk deliberately.”

Bad weather and high waves

At the end of the war in November 1918, UC-71 was due to be turned over to the Allies, in common with other German Navy vessels.

However, while heading from Germany to Britain on 20 February 1919, the submarine sank to a depth of 22m off the small archipelago of Heligoland. The captain sent a telegram blaming bad weather and high waves for the loss of the vessel.

Working with underwater archaeologist Florian Huber of scientific diving company Submaris, Rowland and Hyttinen carried out four one-hour dives on the 50m-long submarine wreck. 

Using sophisticated stills and video cameras and high-intensity lighting equipment, they captured images in “unprecedented levels of detail” to enable photogrammetric reconstructions to be made.

Although previous licensed dives had charted the protected site and recovered the U-boat’s net-cutter, the new 3D images were said to provide considerably more detail.

“It was a flat seabed without too much silt, which made the process of capturing the wreck fairly easy,” says Rowland, who has previously surveyed the wreck of HMS Royal Oak. “Indeed, compared to some of the wrecks near Orkney, it was a walk in the park.

“It feels like we’re making a portrait and, while we’re using sophisticated cameras, it’s not vastly different from using an iPhone. People watching us say it looks like underwater synchronised swimming, and I suppose it is. 

“We try to keep the same distance apart and travel at the same speeds to ensure we have an accurate picture of the vessel.”

No act of war

For a WW1 wreck, UC-71 is described as being in an unusually good state of preservation., “This wreck is different from many others because it was sunk by an act of defiance, not an act of war,” says Rowland, “While the conflict may have been declared over, for those who sailed on submarines such as UC-71 there was still a tremendous sense of loyalty to their crew, their boat and their nation.

“I’ve spoken with navy veterans in the past and they have asked me why we put these images together, particularly on wrecks where people have died. For me, the answer is not always about the vessels, but for those who were onboard.

“While nobody died in this sinking, UC-71 is associated with a great loss of life at sea. By capturing this particular wreck, we are able to capture a moment in time that allows us not only to study this single act, but also serves to remind us of those whose lives were claimed by the vessel during the hostilities.”

There are now plans to use the imagery to produce a 2m-long 3D model of the wreck to sit alongside the crew-member’s journal at a museum on Heligoland.

Also on Divernet: Divers’ new imagery lights up Scapa warships, Wreck Tour 10: The UC-70, Wreck Tour 165: The UC-42, Dive Scapa Flow