FWIW - If you're going to do it, perhaps it could be a small paddle wheel that could also be installed at a waterfall or stream near camp for overnight charging.

Geesh, with all this reliance on electricity, I'm sure in 20 years there will be a proposal for every designated camp site in the BW to have solar panels, wind turbine, hydro turbine or biomass reactor recharging station.     

get me cell tower coverage first 

I'm just curious , there are solar cells that are small and will charge battery powered stuff why would the additional drag of a water powered unit be preferred? REI has several in different sizes including ones that are foldable for compact storage. Just set them on your pack between thwarts while you are paddling.

Regards,
Chuck

Like I said, I don't use electronics and even if I decided to get fish finder/GPS, I'd make do with lithium batteries for a little as I would use them.

Idea was just a out of the box thought, an alternative to solar.
My idea wouldn't be something you kept mounted permanently, something you would put in water if/when you need power. People paddle with outboard mounted fish finder transducers. If done right, I don't think the drag would be a big factor, especially in a tandem setting.

You could probably adapt to use with any running water source in or near camp?

I agree, solar will probably be in all the items mentioned.
I wouldn't be surprised to see some sort of lightweight/collapsible wind powered generator being developed for back country areas.

I also like the battery charging idea using the modified hand crank flashlight.
Maybe not to recharge totally dead batteries, but to keep them topped off.  Siting around campfire at night a few minutes of cranking right/left hands would keep the rod/reels muscles in fine tune

For another source of recharging ... here is another one a bit outside the box:

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Wonder if the wind turbine could be waterproofed to use as a water-driven impeller?

dd