↑ “Naval Architecture for All”. Ủy ban Thống kê Vận tải Hoa Kỳ. Không rõ. Truy cập ngày 13 tháng 10 năm 2008. "Historically, a very important and standard cargo for European sailing vessels was wine, stored and shipped in casks called tuns. These tuns of wine, because of their uniform size and their universal demand, became a standard by which a ship's capacity could be measured. A tun of wine weighed approximately 2,240 pounds, and occupied nearly 60 cubic feet (ref.1)." Today the ship designers standard of weight is the long ton which is equal to 2,240 pounds. (quoting Gillmer, Thomas, Modern Ship Design, United States Naval Institute, 1975 Kiểm tra giá trị ngày tháng trong: |date= (trợ giúp)
