Was a real U-boat used in the filming of Das Boot?
In a manner of speaking, yes; but actually, no. Two full-size mock-ups of a Type VIIC boat were built, one for use in outdoor scenes, and one for the interior scenes. The mock-ups were built according to U-boat plans found in Chicago’s Museum of Science and Industry. The appearance of interior and exterior was duplicated as closely as possible; however, the controls were non-functioning. The outdoor mock-up was propelled with a small engine. Additionally, a mock-up of a conning tower was placed in a water tank in the studio to simulate outdoor scenes not requiring a full view of the boat’s exterior. The interior mock-up was mounted 16 feet off the floor and was shaken, rocked, and tilted up to 45 degrees by means of a hydraulic apparatus. Several models of varying scales were used for exterior shots; in some cases the camera speed was altered so that the wave action and model movement matched that of a full-size U-boat in the open Atlantic. A scene near the beginning of the movie shows
