I think that also a good testament to the quality of the fleet boats is that once the war was finished, and the americans got hold of the Type XXIs to examine them the only things borrowed were:

-Snorkel
-Improved underwater hydrodynamics (Streamed bow, deck gun gone, new conning tower fairing)
-Enlarged battery capacity

With all that implemented, -and besides the snorkel and batteries, it was largely an external, almost cosmetic change- that fleet boats actually surpassed the Type XXI in performance, plus they also had way more advanced electronics (Radar, active sonar, etc.)


In any case, it is worth saying that both german and us (and british) engineers and designers were top notch, and the cream of the cream by the 1930s. But german ones were hampered severely by the Versailles Treaty and political/doctrinal (wolfpacks) matters and actually just could develop modernized -and well built, with german quality- updates of the WW1 submarines. Us and british ones largely had to cope with lots of money restriction after WW1, and also with a ridiculous doctrine that declared any submerged submarine close enough to an ASDIC equipped destroyer as potentially dead. But in all, they had more freedom of movement than german ones, because submarines were not prohibited for their navies, as well as a huge backup from the rest of the navy development (naval radar, etc.) and that pays off.

:D Folks dismiss Wikipedia, but in this area it seems their information is as good as any online.

Always! You too.:)