You could probably mount these on top of some sort of mast so the actual sail clears the containers. You'd lose the space the columns take but that's still a lot less containers lost than the picture suggests.
The problem with using it for container ships isn't necessarily the height (although that could be a problem, as retraction for bridge clearance requirements makes mast engineering a lot harder). The problem is heeling due to the wind. We already have a fairly large problem with containers falling off of ships and being lost at sea, and this could only make it worse.
