Mush,
Was looking at U-boat.net just now - looking at Walther boats but found a list of Boats never built, including the type XI U-Cruiser:
Type XI U-cruisers
Huge U-boats, designed in 1937-1938, with 4 127mm deck guns in two gun-towers (one fore and aft of the conning tower). 6 torpedo tubes (4 in the bow and two at the stern, all below the CWL). One Ar 231 small aircraft in a watertight 2.6m in diameter container shaft. These boats were to have a crew of about 110 men almost double that of any constructed German U-boat. 4 contracts (U-112 thru U-115) were awarded to the
AG Weser yard in Bremen on Jan 17, 1939 but wisely cancelled at the outbreak of war in September that year and none of the boats had been laid down at the time (some sources mention U-112 as being laid down but that does not make sense). These boats are often claimed to not only have been completed but sailed, usually on very clandestine missions and for good measure words like SS, Hitler, Bormann and the like are thrown into the mix. None of this is true and they very certainly not black as some suggest as it is somewhat hard to paint something that does not exist black.
Now THAT would make a real Uberboot!