In December 2020, the Norwegian Coastal Administration (NCA) visited the wreck of the German WW2 warship Blücher at the bottom of the Oslo Fjord. The purpose was to investigate a large crack across the bottom of the wreck, which is laying upside-down on the seabed at 90 meters depth. There was concern that the crack was propagating, threatening the structural integrity of the 80-year-old shipwreck. Using an ROV and a Willy 500 kg | 1100 lbs magnet, they successfully mounted a yardstick across the crack, and left it there. 

One year later, December 2021, the NCA returned to the site to check on the crack. Was it growing? Was the stern at risk of breaking loose and coming hurdling down the abyss, spilling oil and ammunition into the environment on its way?

They were able to breathe a sigh of relief. The crack seemed to be exactly as wide as a year earlier. Perhaps even a tiny bit narrower, which would have been caused by the hull slowly settling into the sediment. In conclusion, the wreck is stable. 

At Blumags, we were also happy to know that the magnet is still doing its job. 

Multibeam sonar image of Blücher, taken by Styrehavn AS

Blücher was famously sunk in April 1940 during Nazi Germany's invasion of Norway. The ship was struck by a combination of shells and torpedoes from the Fortress of Oscarsborg, which had been critically underestimated by Hitler. This important Norwegian victory - although temporary - delayed the invasion long enough for the king to safely escape from the capital before the Germans made landfall.