The main problem in thruster design is how to isolate engine from water. There are three solutions used to keep engines away from water:
- Rotary shaft seal
- Magnetic coupling
The best and more complicated is solution 3. The engine is perfectly isolated from water because it is connected to the propeller using magnetic coupler.
Solutions 2 and 3 are similar. In addition it is recommended to fill the engine housing with the oil to compensate pressure.
Schematic thruster view
Thanks to 3D printer we’re able to build thruster with magnetic coupler. The following video shows work in progress.