donquijote1954 wrote:
Howdy!

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?

Thanks!

I'd suggest trying a gallon plastic jug full of sand, cement, scrap
metal, or anything heavy.
The plastic won't scratch up the bottom of the boat.
Tie a line to the handle on the jug.
In my neighbourhood we have plastic recyling so you can find plastic
jugs at the curb on garbage day. Cheap to replace when necessary.
In pre-plastic times we used a gallon paint can full of cement on a 16
foot fishing boat.

Boating books say to put out 5-6 times a smuch line as depth, ie in 6
ft of water put out 30 ft of anchor line. That's partly to get the
spokes on patented anchors to dig in but also to put some spring in the
line to reduce anchor drag.