Bismarck in port in Hamburg

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On 15 September 1940, three weeks after commissioning, Bismarck left Hamburg to begin sea trials in Kiel Bay. Sperrbrecher 13 escorted the ship to Arcona on 28 September, and then on to Gotenhafen for trials in the Gulf of Danzig. The ship's power-plant was given a thorough workout; Bismarck made measured-mile and high speed runs. As the ship's stability and manoeuvrability were being tested, a flaw in her design was discovered. When attempting to steer the ship solely through altering propeller revolutions, the crew learned that Bismarck could be kept on course only with great difficulty. Even with the outboard screws running at full power in opposite directions, they generated only a slight turning ability. Bismarck's main battery guns were first test-fired in late November. The tests proved she was a very stable gun platform. Trials lasted until December; Bismarck returned to Hamburg, arriving on 9 December, for minor alterations and the completion of the fitting-out process.

Source: Wikipedia.org