Divers recovered a propeller from a World War I submarine on Monday, June 17 at the entrance to Cork Harbour.

It is believed to be part of the wreck site of the UC-42, the German World War 1 mine-deploying submarine, though this can only be fully confirmed on closer analysis of the archaeological object.

The project is very much a collaborative one, with project leads being a joint effort between Blackwater Sub-aqua Club and Mizen Archaeology, and supported by the National Monuments Service of the Department of Housing, Local Government and Heritage, the National Museum of Ireland and the Federal Republic of Germany through their Embassy.

Is this the propellor off UC-42, the German World War 1 mine-deploying submarine. It can only be fully confirmed on closer analysis of the archaeological object

During World War I German forces organised a deadly submarine offensive in a bid to obstruct British supply routes and the entrance to Cork Harbour was regularly mined necessitating frequent sweeping operations by the British Navy.

The UC-42 sank in 30m of water, just outside Cork Harbour off Roche’s Point, on 10th September 1917 when a mine it was carrying exploded. All 27 crew on board the UC-42 were lost.

Later in 1917 an oil slick over the sunken vessel alerted the British Navy, who then dropped depth charges in the area and sent divers to investigate. They found the forward mine shoot empty, and the stern completely destroyed, indicating that one of the mines detonated prematurely. The divers discovered the hatches were open, suggesting the crew had attempted to escape. The periscope and documents including control room logbook were recovered as evidence.

The dive boat over the site of the wreck off Cork Harbour and below diver Gearoid O Looney enters the water to retrieve the propellor

The exact location of the submarine remained unknown over the intervening years but was identified in recent years during seabed mapping for a pipeline project. It has since become a popular dive site. As the wreck is over 100-years old it is automatically protected under the National Monuments Acts 1987-2014 and a licence is required to dive the site.

Last year, while inspecting the submarine Timmy Carey of Blackwater SAC discovered a previously unidentified propeller lying close to the submarine. ‘’It was lying on the seabed detached and knowing that it was vulnerable to potential damage from trawling, anchoring or salvage, I knew I had to put a plan in place to safeguard the object.’’ Timmy discussed at the time.

He spent much of last year liaising with the National Monuments Service, the National Museum, and the German Embassy to ensure that all of the correct procedures, including all requisite licences, are in place to recover the object.

Malcolm Noonan TD, Minister for Nature, Heritage and Electoral Reform, said: “I am very pleased that our National Monuments Service was able to support this project, along with colleagues in the National Museum of Ireland, providing advice on the dive and recovery and conservation of the propeller. The UC-42 wreck is a significant part of our underwater cultural heritage and the final resting place of the German crew who were on board. It remains incumbent on us all to ensure we respect their remains. A collaborative project like this highlights what can be achieved on a shared heritage basis, bringing together the diving community, the commercial archaeological sector, our German Embassy colleagues, Local Authority and the general public to raise awareness of the heritage of our seas and how, together, we can ensure its protection and appreciation.
Over several months, a dive team of six divers, including underwater archaeologists, carefully assessed, recorded and excavated the propeller in preparation for recovery. Finally, this morning the historic object was raised onto the MV Harpy dive boat of Kinsale (skippered by Carroll O Donoghue), and brought ashore.

Underwater archaeologist, Julianna O’Donoghue, of Mizen Archaeology will continue to archaeologically lead, including the conservation of the propeller in advance of going on display in Spike Island Museum, in agreement with Cork County Council. Ms O’Donoghue said I’m anticipating the conservation process will reveal markings or finer details on the propeller which will further our understanding of the site, and confirm, or otherwise, if it is associated with the UC-42 wreck. The safe recovery, conservation and presentation of the object also very much denotes a best practice project relating to our fragile underwater cultural heritage.

The Ambassador of Germany to Ireland Cord Meier-Klodt added: “I would like to congratulate all involved for the successful recovery of the propeller of UC-42. We are now looking forward to the conservation work, which will hopefully allow for the propeller to be exhibited in a local museum. This will encourage more engagement with and learning about both German and Irish wartime history.”

Timmy Carey further added that the project also highlights how, if we all work together, especially with the relevant authorities, we can successfully recover vulnerable material from wreck sites like the UC-42 submarine. The project is significant as it offers an opportunity for the wider public to engage and interpret objects from such wreck sites and increase our understanding and appreciation of Ireland’s maritime heritage.