This video features one that could be great for water propulsion, making it safer, for swimming pools and for fish.
It uses three cone shapes on a rod, the middle one of which moves forward and backward. As it moves forward the water is “reflected” against the forward cone to push water backwards; and as the middle cone moves backward, it pushes water back with it then as well. So the “forward-backward” action of the middle cone results in pushing the unit forward in the water.
The advantage is that it is much safer than a propeller, and it may be more efficient than a propeller. Bobby says it is around 60% more efficient than propellers.
The prototype toy he built (photos shown in the video) was so popular, all the kids wanted to play with it at the beach. “Can I have a try?” “Can I have a turn?”
He would like to see this patent-protected technology move forward.