There was no recorded wreck at this locale so it absolutely was documented for the appropriate authorities, including the Receiver from the Wreck (RoW). They were regarded exceptional boats. Throughout the war 8 have been sunk, 3 surrendered and have been eventually scrapped, and two had been thought of lacking. https://u3192209.p2blogs.com/33053001/the-smart-trick-of-u31-that-no-one-is-discussing