What you're seeing, the_boat_captain, is actually a meticulously researched and historically accurate simulation of the work of an often overlooked part of the Kriegsmarine, the UBootParkierungsSpezialAbteilung (or "Special Detachment for U-Boat Parking" in English).
They were responsible for the correct and proper assignment of docking space for the U-Boats of the Kriegsmarine. Without proper assignment, the harbor master's documents and the loading manifests might get messed up and, as we all know, a sure ticket to clearing minefields on the Eastern Front was to create discrepancies in the Reich's documents.
They were also way ahead of their time, technology-wise. On the bottom of the bow portion of the hull there was a small radio transmitter with a unique code that would transmit continuously when it found itself in range of one of the receivers at the bottom of every docking bay (much like your modern day toll road tag). If the code matched, the steel gate blocking the entrance would lower into the ocean floor and allow access. If it didn't match, the U-boat trying to access a different boat's docking space would ram into the gate.
Initially, this radio transmitter was attached to the stern, since parking your boat with the bow facing out could save valuable time when departing, but it was found that reverse parking a 750 ton U-boat was more trouble than it was worth. Not because of the difficulty of the maneuver, but because the additional time needed to perform it was far more than could be saved by it. Several studies from 1937-1939 were performed to confirm this.
Of course, I may just have made all of the above up but hey, it's my story and I'm sticking to it.
