Initially, diesel propulsion was planned for these ships, as had been used for the three "Panzerschiffe". It was decided to use superheated steam propulsion, as the required total output for the desired speed was three times that of the "Panzerschiffe". In the case of triple-screw ships, this would have meant more than twice the horsepower per shaft of the "Panzerschiffe", and in the case of a quadruple-screw ship, this would have amounted to more than 40,000 horsepower per shaft. This requirement was beyond the diesel technology then available, and devising engines that could meet this demand would take an unforeseeable amount of time. Since high-pressure superheated steam had already proved successful, it was considered the most suitable choice for high power machinery.