donquijote1954 wrote:

I'm considering a heavy anchor (perhaps 6.5 lbs or heavier) such that
if --for example-- my partner gets tired in heavy wind I can have the
canoe stay put while she rests. Or if I must abandon the flooded canoe
and swim, I can come back and retrieve it at the same spot the next
day.

What do I need?

You want an anchor that holds, which is not necessarily the same thing
as a heavy anchor. There are lightweight anchors that hold quite well.
And heavy anchors that don't.

The primary determining factor is what sort of bottom you canoe over.
The characteristics of the bottom determine the optimum anchor. That
said, a basic small danforth should be fine for most situations.

BTW, do not abandon your boat. It drives the first responders crazy.
Thanks.

//Walt