I zoomed in on the skiffs because I wanted to see what they were doing. I'm still not sure, but I imagine they could have been helping to push or maneuver the barge. They seemed to be butted up behind it.
A couple of hours later, the barge passed again, going upriver This time I got the towboat in the picture (left) and the two skiffs are alongside. You can see the two tall poles (the function of which you'll see tomorrow), and other poles lying on the deck sticking out over the rear of the barge.
Here's the towboat, pushing, and one of the skiffs.