JW411 (#10887),
Your: ...."It is 1942 .... and the Americans are having huge problems with U-boats on the east coast of the USA"...
Exacerbated by two factors: Coastal shipping was silhouetted against the lights of the coastal towns (was there a blackout, and when ?). And the "Radio Range" signals nr the E. Coast were being used by the U-boats for navigation: they were switched off and civil air transport disrupted for a while. [from memory]
Danny.