One of our Willy 500 models is now sitting on the wreck of the German WW2 heavy cruiser Blücher in the Oslo Fjord. Mounted on it is a yardstick used to measure the size of a crack in the hull over time. The magnet was mounted by ROV in an operation led by the Norwegian Coastal Administration (Kystverket).
Blücher was famously sunk in April 1940 during Nazi Germany's invasion of Norway. The ship was struck by a combination of grenades 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.
80 years later, the wreck remains on the bottom of the Drøbak Narrows. Back in 1994, most of the oil inside Blücher was removed. One of Blumags' own team members, Dag Ammerud, was involved himself in that operation. However, it is estimated that 700 tonnes of ammunition still remain, along with the oil inside 12 tanks adjacent to the ammunition holds. This, along with the deteriorating hull structure, poses an obvious threat to the local environment.
The biggest concern is related to a large transverse crack in the hull, approximately midships, which threatens to split the wreck into two pieces. So to monitor the development of the crack over time, the Norwegian Coastal Administration wanted to place a yardstick right across it. As the wreck is laying at a depth of 90 meters, this was done by ROV instead of divers.
Using a Willy 500, the ROV team removed the eye nut and attached the yard stick in its place. The hull was scraped to remove the thick layers of marine growth, before the ROV could place the magnet on the hull. The operation was a success, proving that the Willy series by Blumags is a useful tool not only for divers, but also ROV's.