Many problems were encountered with designing the ships, the most prevalent being armor. The required maximum speed of meant that the minimum length had to grow from the original to . It also meant that the beam could be a minimum of —unless diesel engines, like those used in the "Deutschland"s, were desired; they would increase the beam by . Unfortunately for the designers, the widened beam meant that an even longer hull was needed to maintain hydrodynamic efficiency. All of this complicated the armor arrangements, as more armor was needed to cover the longer length and widened beam. Eventually it was deemed that it was impossible to include diesel power on a displacement.