The stern certainly did make some movements during the breakup and beyond. I believe the main cause of this was the port list. As the stern fell back, it would have bobbed around in the water for about a minute, gradually increasing its tendency to lean over to port. This was witnessed and described by Charles Joughin as he saw a group of people pile up violently in the well deck. This would have rotated the deck 90 degrees away from starboard as observed by Jack Thayer as the propellors were exposed to him. This was all the
Titanic twisted around. When Lightoller said the stern "turned around," I don't think he meant a complete 180. And then as the stern was pulled down by the bow, the tail end of the ship would have shot upwards over to the spot where the bow had gone down moments before. This is portrayed in "Titanic: Honor and Glory"'s real time sinking video, History Channel's 2013 simulation, the 2012 "Final Word" National Geographic simulation, and in Parks Stephenson's 2006 CG sinking diagrams.
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More Questions Than Answers, Part 2