There's a difference between evaulation and being
the backbone.

The fact is none of the type XXI's in US or RN services
were operational for very long and certainly didnt
form the backbone of the submarine force. The USN carried out the GUPPY
conversions while the
RN built the O & P classes

Yeah right,there is also a difference between inventing and copying (stealing)
a technology.
Right Mr.Willshaw?