Hello, we have a by-the-river 20km cycleway from the city centre (Prague, Czech Republic) to the south. Then a 10km bit is missing and probably will be never built as there is the river and rocks on both sides with two-lane road hardly fitting.
The boat might fit in between the city cycleway and a short, very low traffic road on the opposite side of the river to the cars bridging 7 kilometres on water.
Essentially, this would enable commuter and recreational cycling as nowadays, you can see only lycra people, because cyclists get killed there (also children got killed by car drivers).
So I though I could build a prototype boat, which could be later used in an automatic rental system with a human administrator checking now and then.
It should be comparatively fast to a bicycle (20 mph/30 kph), which is rather fast on water, stable and easy to operate (although I have no idea how to make docking sufficiently easy for first time rentees).
The boat would be used mostly by single commuters or by families with children (recreational), so it should be able to accommodate a bike, 1-2 children’s bike, 1-2 children and one adult. So around 200 kg of load.
I think it should be a catamaran to be stable and fast and that around 3 kW would achieve ~30 kph speed (for me, for the rentals it depends on legislation, I haven't explored all the possibilities, just seen max of 15 kph without a license).
As for the propulsion system, here on ES I’ve learned I have 3 options: an underwater propeller, a jet drive (safe, quite durable) or a paddle wheel (efficient, durable).
And motors – I can use RC (jet drive, paddle wheel with a belt reduction?), hub motors (paddle wheel?) and for propeller I would need to use some kind of a gearbox.
For that distance I need a sub 2 kWh battery, probably lifepo.
Paddle wheel seems the simplest, but what if you would 3D print the jet drive (from an existing template) or buy a good fit propeller? How would you build a paddle wheel?