A river powered ferry for cars/people. Hello, Powered by the movement of the river, while attached to the cable strung across the width of the river. As the river flows, it pushed the car ferry across the river without a motor running for power. It was pure flow of the river and nothing else. The attachment on rolling wheels was smooth on the heavy duty wire strung across the width of the river. The river always flowed (in the photo above from left to right) Jnaki Coming back across, the same flow still powered the same ferry at the same angle, but the cars were facing the other bank. Note: When my wife and I were in Europe, we were able to cross the fast flowing Rhine River in Germany on one of these “river powered ferries.” It was our first time being on one and it is an unusual way to cross without any noisy motor pushing the floating ferry both ways. The Rhine River is a fast flowing river and if the ferry was motor powered, it would still be fighting the current and perhaps being pushed farther down river, until the captain steered it back to the original landing. Or, perhaps the flow would have dictated the drift of the motor powered ferry. But, for us, the attached ferry went from one specific place directly across the river to the other shore in a direct line, and not floating down with the current. "Silent running" was the mode of the day... YRMV