Moving U

Following the closure of the Historic Warships Museum at Birkenhead in the north of England earlier this year a WWII German U-boat had to be moved out. The Mersey Docks and Harbour Company contracted Abnormal Load Engineering Ltd (ALE) and Nuttall John Martin (NJM) to move the museum's main attraction 400 m further along the quay to clear land for development.

When U534 was sunk off the coast of Norway in May 1945 no one was killed so it was not classified as a war grave, allowing its current owner to raise it in 1993. It has been part of the Historic Warships display at Birkenhead for 13 years.

ALE had to react quickly to the client's strict programme requirements for the movement. The relocation project was completed in less than three weeks, from concept planning to completion.

U534 is 70 m long and weighs 900 tonnes. To move the vessel ALE had to make detailed engineering investigations into the issues and risks. Before mobilising equipment to site, method statements, risk assessments and engineering calculations were prepared and submitted to meet both ALE and NJM's requirements.

Due to the age and history of the vessel how much of it was left intact was unknown. Its exact weight and centre of gravity position were not available. ALE engineered the chosen trailer configuration based on worse case historical design data available for U534 and set parameters for maximum lateral chambers and longitudinal gradients. This was detailed in the method statement documents and the hold points were reviewed, assessed and signed off prior to each step of the process being completed.

Before the move a test lift was carried out using an assembly of 48 axles of Scheuerle self propelled modular transporter (SPMT) and the weight was calculated at between 850 and 900 tonnes.

The SPMTs were connected to each other via a data cable so that all units were linked electronically. Once connected, they are programmed to act in synchronization. All functions were operated from a joy stick type control box worn by the operator. Once the U-boat parameters were programmed into the computer, the computer monitored the level of the structure and adjusted the hydraulically driven wheels of the SPMT automatically at all times.

The U-boat, which is owned by Danish company Den Bla Avis, will stay in its new position for a short time until a more permanent location can be found.