http://www.hmshood.com/history/timeline4.htm
Career Timeline of H.M.S. Hood, Part 4
16-21 May: Based on reports that Bismarck was likely to attempt a breakout into the Atlantic, the ship was more-or-less on alert. Strategies were planned and discussed.
http://www.worldwar-2.net/timelines/war-at-sea/atlantic/battle-of-the-atlantic-index-1941.htm
17/05/1941 The German battleship Bismarck and the heavy cruiser Prinz Eugen leave Gotenhafen in the Baltic to begin operations against British convoys in the Atlantic (Operation Rheinübung).
So BISMARCK’s on the move.