Abstract: A dynamo-electric machine, for example a marine propulsion unit, includes a stator and a rotor in the form of an impeller. The impeller is rim-driven and includes an annular core of ferromagnetic material, on which are provided layers in the form of an environmental enclosure and electrically conductive sleeves. Appropriate selection of the materials and thicknesses of the layers enables the starting and normal running performance of the machine to be optimized.

Abstract: A dynamo-electric machine, for example a marine propulsion unit, includes a stator and a rotor in the form of an impeller. The impeller is rim-driven and includes an annular core of ferromagnetic material, on which are provided layers in the form of an environmental enclosure and electrically conductive sleeves. Appropriate selection of the materials and thicknesses of the layers enables the starting and normal running performance of the machine to be optimised.

Abstract: A rim driven electrical machine for interaction with a flow of water, comprising: a rotor mounted within a housing, the rotor including at least one circumferential conductor and a central passageway, the central passageway for receiving at least one blade arrangement for rotational interaction with a fluid within the central passageway, and; a stator supported by the housing and arranged circumferentially around the rotor, the stator including windings for providing a travelling electromagnetic wave for interaction with the at least one circumferential electrical conductor of the rotor, wherein the stator extends only partially around the circumference of the rotor so as to have a first end and a second end separated by an arcuate angle.