| CPC B63H 21/17 (2013.01) [B63H 1/14 (2013.01)] | 16 Claims |
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1. A propulsion unit for a waterborne vessel, the propulsion unit comprising:
an electrically powered outrunner motor having a stator and a rotor, the rotor being configured for rotation around the stator about a stator axis;
a plurality of propeller blades fixed to the rotor for rotation therewith about said stator axis;
first and second components forming part of or being fixed to the stator, the first and second components being spaced apart along said stator axis with the rotor being located axially between the first and second components;
a first rotary seal located between the first component and an opposed first end surface of the rotor; and
a second rotary seal located between the second component and an opposed second end surface of the rotor,
wherein the first and second rotary seals are configured to substantially prevent ingress of water into a rotor-stator gap,
wherein at least one of the first and second rotary seals comprises a pair of rotary seal subassemblies separated by a plurality of ball bearings, wherein the rotary seal subassemblies are respectively secured to the rotor and one of the first and second components, and
wherein the rotary seal subassemblies comprise respective opposing ball bearing rings configured to provide respective opposing glide surfaces for the plurality of ball bearings.
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