I ran across this in Canadian Canoe Routes, and Gmap4 doesn't seem to have been discussed here before, so hopefully it will be of use to someone.

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Briefly, Gmap4 is a free mapping tool with integrated topos and Google Earth photos. It has capabilities for adding routes, GPS tracks and waypoints.

I have just started playing with it, so I apologize to the developer for not having done full justice to the capabilities of his software in that short description. But the interface is quite intuitive, so try it out for yourself and see if you find it a useful tool for canoe trip planning.