When the Third Reich collapsed in May 1945, teams of American, British and Russian submarine experts converged on German dockyards to locate and recover every scrap of information about the latest U-boat designs. In particular they wanted details of the Type XXI and the even more advanced HTP-driven Type XVII. The Americans and British raised two Type XVIIBs and put them back into service for trials, while the Russians took several hull sections away.
It was 1918 all over again, with the victors almost coming to blows over their shares of the loot. In the end the Americans and British got the lion’s share because their armies had overrun the principal shipyards and factories in the West. In all, nearly 40 U-boats were incorporated into various navies, some for trials but others as part of the postwar fleet.
Although the Walter turbine was of great interest, it proved unreliable and offered only limited endurance at great cost. Only the Royal Navy went to the lengths of building HTP boats postwar in an effort to make the system work, and for a while its two experimental boats, HMS Excalibur and HMS Explorer, established a new underwater speed record by exceeding 27 knots. The Type XXI offered a more useful line of enquiry, although the influence of the design itself has been greatly exaggerated by a number of historians and analysts. But there were a number of problems: the hull form had not been tank-tested and proved unstable in service, the internal arrangement of equipment was far from ideal, and there were serious weaknesses in construction. Although the Soviet Navy built a number of boats which closely resembled the Type XXI, the Royal Navy and the US Navy were happier to adapt the best features to fit in with their own designs. Thus the concepts of the Type XXI – the large-capacity batteries and the mechanical reloading gear for the torpedo tubes – became standard around the world.
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I would to a degree put the Type XXI in the same category with many WWII German innovations in aircraft design, missile development, naval propulsion and myriad other categories: the concepts were revolutionary, but inadequate effort (especially focus) went into refinement and there was far too little time to support properly even a fraction of the projects attempted. Nearly every innovation in military or aerospace technology introduced up to 1970 had at least appeared on German drawing boards by 1945, but many of these took many years of development before they could be of practical use.
This was rather typical of the German war effort, I believe: the fascination with (and near deification of) technology without the discipline of good systems engineering. The Germans could have achieved a great deal more had they targeted a much smaller group of technologies to pursue vigorously while shelving many others.
The Type XXI obviously demonstrated what were the signs of rushed (and incomplete) development rather than fundamental flaws in concept. The first couple of boats completed were apparently declared unfit for operations by a Kriegsmarine desperately in need of a breakthrough weapon. In addition, early tests showed that entirely new tactics needed to be developed to exploit the characteristics of the Type XXI, and while never wishing to underestimate the adaptability of the Germans, that would have taken some time also – and given the Allies time to develop new weapons and tactics of their own.
I am of the opinion that fully operational Type XXIs could not have come in any number much sooner than they did (spring of 1945). By then the preponderance of Allied weight was on the verge of collapsing the German Reich, and even an absolutely horrendous merchant loss rate could not have saved the Germans.
The fact that most of the submarine designs up to the Albacore showed the influence of the Type XXI points to the basic soundness of the design. However, even in rushing to deliver a demonstrably underdeveloped product, the Germans could not incorporate all the innovations quickly enough to change the course of the war. I would conclude that for all practical purposes the Battle of the Atlantic was won for good by the summer of 1943, and there was, from there forward, no time left for any innovation not already refined and nearly ready for full production in May of 1943 to alter that fact.
There was little wrong, conceptually, with the Type XXI. The product, however, does not appear to live up to the concept.
