There was no recorded wreck at this area so it was described into the appropriate authorities, including the Receiver of the Wreck (RoW). They had been viewed as great boats. Through the war 8 ended up sunk, 3 surrendered and were finally scrapped, and two had been thought of missing. https://landenmguhx.blogolenta.com/31095526/the-smart-trick-of-u31-that-nobody-is-discussing