My older brother was a US Navy submariner at the end of WWII. He was subsequently assigned to the US Naval base in Key West Florida where captured German U-boats were being examined and tested for capability. He never talked about what was learned from the examinations and testings. I suppose it was classified information. What he did say was that every time he left port on one of the U-boats he always thought he may not return. He said he never had this concern while serving on the US Navy subs...