XXI

The XXI was designed to operate underwater full time, although it could still operate on the surface from a handling point of view. Typically it put up the snorkel once a night, but in a pinch it could stay down deep over 5 days and cover over 350 nautical miles in the process. This type of operation nullified the radar of the period. HF-DF was also vulnerable to operational doctrine. Had the U-boats shut up, then both ULTRA and HF-DF would have been essentially useless. The wolf pack tactic was obsolete and counterproductive by 1943.

The way to use the XXI was to send them out to a predetermined patrol area under radio silence and keep them silent, receive only. The XXI had the capability of finding a convoy using sonar, intercepting it, firing its full torpedo load while under the convoy and returning to tell the tale. Equipped with a high speed wire guided and next generation acoustic torpedoes, they could also have taken out the escorts. The XXI could outrun "Fido" which had poor sonar and the sonarbuoys would have been harp pressed to hear a XXI at 200 meters. With the right tactics and torpedoes, the XXI would have been the scourge of the Atlantic and very hard to kill.

Regards,
SuperKraut