Computers and Electronics What does a Supercargo do? What does a Supercargo do? The duties of a supercargo are defined by admiralty law and include managing the cargo owner's trade, selling the merchandise in ports to which the vessel is sailing, and buying and receiving goods to be carried on the return voyage. Related Posts:Is the UK under maritime law or common law?The Scribes are defined in the Bible by the word SCRIBE.Start sailing on the water.What is the return policy at Rooms to Go? Does Rooms To Go offer free returns?