U-class boats were small, nimble submarines suited to Mediterranean operations and economical construction. Their surface displacement began at roughly 550 tons and rose to about 640 tons in larger boats, around a quarter to a third of the size of the later Oberon class. Describing them as training submarines alone understates the attention given to light construction and smooth hull shapes for underwater performance. Of 49 boats built during the war, 20 were lost, although one boat's subsequent raising complicates how the losses are counted. From Malta, torpedo deliveries were less reliable than fuel supplies. Crews therefore closed the range aggressively but fired cautiously, seeking a strong chance of success before spending a scarce torpedo.
Chapter · 48:36-53:14
U-class boats, Malta, and torpedo economy
The compact U class combined shallow-water agility with economical construction, but Malta-based boats had to make every torpedo count when supply was uncertain.