In terms of deadweight tons
NOTE: Deadweight tons – is the total weight in long tons (2,240 pounds) that a vessel is transporting, including ballast and bunker fuel, crew and equipment, and cargo.
SOURCE: U.S. Department of Transportation, Maritime Administration. Maritime Vessels Calls at U.S. Ports by Vessel Type. http://www.marad.dot.gov/ (accessed June 17, 2011).