Doug wrote:

What is navigable?

Usable by commercial vessels traveling both up and downstream. For example, the
Tennessee river is considered navigable for its entire length; however, neither
the French Broad nor the Holston (which form the Tennessee) are considered
navigable. Quite large boats can travel either the Holston or the French Broad,
and, in fact, Tennessee was settled in part by commercial vessels (flatboats)
coming down the FB from North Carolina. You can't take a commercial barge up
either river today, though.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.