For marine purposes are used both A.C. and D.C. motors. Easy speed control characterizes D.C. motor, but its initial cost is higher than that of A.C. motor. Nowaday, in the starting and speed control methods of A.C. motors, progress has been made, and is applied very popularly for marine motors. The generator of self-exciting type, which saves engine room space, has been developed and shows excellent property for starting motors.
