It looks like a steel barge, it's as strong as a steel barge (I know, I was invited to hit one with a 14lb sledge hammer by the builder) but it's not made of steel. It can be built to cat 'D' or 'C', and only weighs in at around 7 tons, so should be easy to push along, stop and handle with ropes.
http://bonviveurboats.com/bv1500.html
