The interior U-boat mock-up was mounted five metres off the floor and was shaken, rocked, and tilted up to 45 degrees by means of a hydraulic apparatus, and was vigorously shaken to simulate depth charge attacks. Petersen was admittedly obsessive about the structural detail of the U-boat set, remarking that "every screw" in the set was an authentic facsimile of the kind used in a World War II U-boat. In this he was considerably assisted by the numerous photographs Lothar-Günther Buchheim had taken during his own voyage on the historical "U-96", some of which had been published in his 1976 book, ("U-Boat War").