Castable depthfinder for river?

I mainly fish from the river bank and I don’t actually know much about the depth or structure of the river. 

I’ve seen some depthfinders that you can attach to a rod and cast out. Do you think this would work for a river with slow to fast current?

Wasnt sure how the current (particularly fast rough current) would effect the devices ability to get a usable image. Or would even work if parts are shallow. 

If it might work, any products someone can recommend?