View of the port main switchboard and to its left auxiliary switchboards 2 and 2a in the electric motor room. This board, made by Siemens, was the standard type of board provided to type IX submarines. It differs from the starboard main switchboard as the latter was installed late in her service to be tested for use on type XXI boats. The main switchboard provides the means to change the speed of that side’s electric motor, or when using it to charge the batteries, to regulate its output voltage. The port side engine order telegraph is visible in the background. (Caption courtesy of Matt Hamacher)