Cyli wrote:

Wind or tide or current
should keep a canoe pointed / placed in one direction for quite a
while with just one anchor.

Until the wind/tide changes. If a river has a steady current, you'd be fine.
Boats routinely anchor with two anchors to prevent drift. You can have one off
each end or two in a V at one end. Perfectly safe unless you use 20' of rode at
low tide in a 40' tide zone. And never anchor beam on to the surf :-)

Mike