[Hooston]

I'm a u-tourist. i try to visit as many historical battles as possible and see how well they have been captured. My latest was May 1941 in the Western Approaches. I saw a few Swordfish and BdU kept telling me about fast moving friendly and enemy warships but the only ships I found were some neutral US tankers! Maybe I should have cheated a bit harder.
Brief historical summary below; but be aware that all sweeping generalisations are complete rubbish.

Historically in 1941-43 the BdU would set up patrol lines across known convoy routes (as given away by decrypts) which would sweep very slowly across the Atlantic. In theory the first boat to find a convoy would shadow it until the rest joined for a pack attack. In practice the radio traffic involved allowed the allies to dodge these lines on many occasions. The BdU were baffled about how boats operating independently did better than those in patrol lines.
Eventually with more boats in 1943 the patrol lines got so big that it was almost impossible to dodge them. This prompted the allies to get their act together in May 1943 and they then quite happily attracted attacks so they could sink more boats.
Finally in 1944-1945 most boats operated independently in coastal waters using schnorkels and homing torpedoes. They did better but were so slow they were reduced to ambush tactics and were so outnumbered that getting detected was a death sentence.