I will try and find the regulation, but in my opinion, any barge must comply with SAMSA's regulation. This entails that the barge will have to have a COF and buoyancy certificate and a skipper licence, irrelative of the HP on the barge.
http://www.samsa.org.za/sites/samsa.org.za/files/MN%2013%20of%202011%20Small%20vessels%20Policy.pdf