Franz von Bock und Polach scrolls through thousands of photos and videos on his computer. White, unspoilt landscapes alternate with mighty ships and detailed shots of snow and ice. His enthusiasm for his field of research also adorns the walls of his office at the TU Hamburg. While an icebreaker makes its way through the frozen Arctic in one photo, drawings by his children show ships in bright colours. "The Arctic has always fascinated me. Of course, it's an inhospitable region, but it always moves me emotionally," says the scientist. The impressions of his last visit are still fresh in his mind.
His two-week research trip to the North Pole began from Spitsbergen together with scientists from Germany, France, Canada and the USA. During the journey through the almost two-metre-thick ice, the researchers spotted whales, polar bears and walruses. At temperatures as low as minus 15 degrees, 24 hours of daylight and constant wind, the team from TU Hamburg and the Alfred Wegener Institute (AWI) carried out a series of measurements on the ship's speed, propulsion power and temperature of the outer hull. Continuous measurements of the thickness and light reflection of the ice were also part of the joint project with the AWI. "If the weather was good, we went out onto the ice and deployed snow buoys for continuous measurements. In foggy conditions, this was often too dangerous for fear of polar bears," says the TU expert, describing the conditions on site.
Not all ice is the same
Back from the Arctic cold, ice research in Hamburg is much more pleasant, but no less complex. This is because where ice previously existed in vast quantities, it first has to be produced artificially in the laboratory. "If we were to simply freeze water to produce model ice, similar to ice cubes in the freezer, it would be far too solid for model experiments on a scale of 1:30. In laboratory tests, we therefore also have to adjust the firmness of the ice accordingly," explains the scientist. In a 10 by 80 metre ice tank at the Hamburg Shipbuilding Research Institute (HSVA), this is done using a fine water mist that is sprayed onto a water surface at temperatures as low as minus 20 degrees. This creates ice crystals, which come together to form so-called ice grains until they collide with another grain and can no longer grow horizontally. In the Arctic Ocean, such a grain can reach a size of several centimetres in diameter. On a model scale, they are much smaller.
Further information
Institute for Ship Structural Design and Analysis
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