From Longman Business Dictionarygross registered tonnageˌgross ˌregistered ˈtonnage abbreviation GRTTRANSPORT1a measurement of the space for carrying goods in a ship. Gross measurement tonnage is obtained by dividing the number of CUBIC FEET of space by 1002the total gross registered tonnage of all the ships belonging to a particular shipping company, country etcThe shipping company owned operating vessels with a combined gross registered tonnage of approximately 136,842 metric tons. → tonnage
