I have a design concept (for oars) which is rather simple but also quite unlike anything I have heard about. The paddle blade consists of many simple one-way valves (if you will) such that the oar need not be lifted from the water and returned to the water. Rather, the oar can be rowed straightly back and forth, but it has very little resistance in one direction while being entirely motivational in the other direction. The elliptical "lifting and returning" of the oar is bypassed, and less human energy is ultimately involved. Please direct any thoughts to my email address. I have other ideas if interested. DNDSERV@AOL.COM