Wow, thanks for all the warnings. You guys clearly have run into many of these problems before.
A little info. This is a tidal river. Where the mooring is, the river is about 25 feet deep at low tide, and over at the dock it probably is 12 feet deep at low tide. I've estimated the flow to be around 4kt to 5kt at peak flow times. My hope is to get 1kw to 2kw out of it, if I can overcome these issues.
I'm contemplating mounting a turbine (gorlov?) out next to the mooring, and having it be 1/2 way between the surface and the bottom. Of course mounting it would be a challenge. It would have to have some kind of mooring base on the river floor, and then either have a solid mounting, holding it vertical 5-10 feet up in the water, or consider hanging it on a line up to a float,
I had NOT thought about 'stupid people tricks', like dropping an anchor THROUGH the turbine. I also had NOT thought about large debris hitting it. While Ive seen all the junk floating on the river surface, I now realize I need to see what junk is moving in the river about 10 feet deep. I had planned to put a wire cage around the turbine to keep anything from hitting the blades.
I did have some really stupid ideas to get the power from the turbine to the river shore. These included having the turbine turn a pump, and have it shoot a stream of water towards a huge funnel on the shore, and create head and flow, to turn another turbine on-shore (stupid, what happens when the wind blows!). Or, the turbine could turn a generator which would light a really bright light with a directional reflector behind it, and beam the light to shore.
I do like the idea of an armored cable with a fail-safe mechanism. So if something really snagged it, it would pull free, and I'd just lose the cable. Also, clearly I need to think about making sure if something hit the turbine or caused it to lose it's base, that I'd not lose it completely.
THanks for the ideas. If there are any more out there, please let me know!
Dave