The bunker was to house 13 assembly bays , each carrying out one part of the assembly process , two bays were underneath box - like structures on the roof that allowed the extra height needed for the installation of periscopes and Submarine snorkels .
The bunker was to house 13 assembly bays ( Takt 1 - 13 ) , each carrying out one part of the assembly process . 
 Two bays ( Takt 9/10 ) were underneath box - like structures on the roof that allowed the extra height needed for the installation of periscopes and Submarine snorkels .