>>1609445If you must use an in-water moored turbine for power generation, I urge you to use one of the floating models. "Floating water wheel" or "floating water turbine," should net you some results. Specifically ones that look like a paddle wheel floating on the water. Some are pretty robust with good metal protection of everything. Others are just one good rain storm away from breaking on flotsam.
I don't recall if this model succeeded commercially, but its design is solid enough.
>off-griddingIf this will be a permanent location, building a sluice and directing water to a hydro power plant will be the best solution. These can also be done with low head. Search, "vortex water turbine" or "gravitational vortex turbine" or "whirlpool turbine". They should look like a letter "P" and are normally made of cement with the turbine paddle in the center of the whirlpool. They can be used with streams that have extremely low head.
