I'll do some checking on the Dungeness and talk to the state real estate authority to get the facts. This is an interesting topic and I'd like to do some research on it so we can get this straight. As far as whether a river is navigable by boat, the government decides that. How you find that out is out of my hands, but the government decides or decided what rivers are navigable. Anything else? When I get an answer from the real estate authority I’ll be sure to post it. Also, an enter tube or rubber raft doesn’t constitute a boat, a boat constitutes a boat. Does this make sense? You can email me for other questions and I’ll be sure to try and get them. Happy fishing!