Roughly 10 years ago we had a chance to build a stream-powered pendulum ferry in Vilnius, which connected two river banks for pedestrians and cyclists for a couple of years.
And this was how a prototype to test the form-factor, physics and streams looked like:
There is a video playlist of presentations and documentations on different stages:
https://youtube.com/playlist?list=PLqgnTDAucZaKwoUmLg67sfkQ-mAwIUKj9&si=rodu2W9bVkBg5C8T
This is so great (and very solarpunky)! A ferries like this could be used to connect the sides of the rivers in so many places!
How long did it take for the ferry to cross the river? (also, if you know: how wide is the river and how fast is the stream?)
River Neris in that part of our ferry crossing is around 70 meters wide, which is crossed in just 2 to 3 minutes. The speed of the stream varies a lot, up to max around 7km/h. It slows down a lot towards the banks, so you need quite steep banks with some stream for the ferry to operate. Putting little pontoon platforms in the water for more stable access is helpful here - they let the ferry embark already a few meters in the water where the stream is usually stronger.
Here near where I live, there used to be a bridge at Vistula river that was destroyed during WW2 and never rebuilt ever since: OpenStreetMap
There operates a seasonal ferry instead. It is old, loud, produces much pollution and has difficulties to start the engine at the beginning of the day. I wander if it would be possible for Uperis to operate in such a place? Could it be modified to take on a car or are they too heavy (or do we reject them from the Solarpunk future? The pass is used mostly by cyclists but not only)? Vistula is much bigger then Neris, here there is around 200m from one bridge-post to the other, and it is known for strong whirlpools.
We did a test on one place in Nemunas with distance around 170m. Technically it worked, but it was much slower and felt psychologically insecure in such a scale (even if actually very stable). It looked like this:
Our model has a lifting power of around 2 tons (but only 10 people, because they can concentrate on one edge). We did carry a motorbike once, but we adapted it only for pedestrians and cyclists because of location and idea. For such a river, I guess, a bigger and probably somewhat different would be needed… And the problem which killed our operation was in fact funding.
We were told to “do business ourselves” by municipality, and the tickets did not let us hire ferry operators, so we just got tired. In other words, it should be supported as public transport, or have some longer-term project to fund the operation, not only installation.
We also had some thoughts and talks about making such a ferry autonomous, like a water drone. The battery and engine would only controll the steering, and the pushing work would still be done by river stream. But that would be totally another level of project, quite appealing though.
Very interesting, the psychological safety aspect of a relatively small watercraft on a big river.
I agree that a ferry like this could be subsidised as a public transportation.
Thanks for a very thorough answer!
