Commercial use places high demands on fast ferry drives with regard to high power at high efficiency, which also inevitably leads to the requirement for less weight. Today, for reasons of comfort, one opts mainly for elastically mounted four-stroke diesel engines with high power density, as well as waterjet drives. The requirement for weight optimization is also valid for all other components of these diesel-mechanical drives. Due to their relatively low specific weight, composite shaft lines allow longer distances between the bearings and therefore less bearing points in comparison to heavier steel shaft lines, thereby saving significant weight. This is also true for the shafts themselves.