At the end of the 19th century, some countries began to be interested in the use of electric propulsion for ships. The reason for adopting electric propulsion is that it has flexible layout, low noise, controllability and reliability.
In addition, electric propulsion inherently has the characteristic of satisfactorily transferring power from the high-speed prime mover to the low-speed propeller.
Electric propulsion has all the advantages of traditional electric drive. Full-submersible motors and propellers are directly installed inside the rotor. Compared with other electric drives, it has the following advantages: the relative magnetic gap speed is high; the sea water is directly cooled; the sea water directly moistens the bearing; there is no rotary sealing device. This principle has the adaptability in terms of the installation position of the motor shape and structure, because the motor can be installed outboard, so it is more adaptable than the traditional electric drive. In addition, this motor/propeller can be adapted to many different applications in many different ways.