Tonnage and poundage Tonnage and poundage Tonnage and Poundage were certain duties and taxes first levied in Edward II's reign on every tun (cask) of imported wine, which came mostly from Spain and Portugal, and on every pound weight of merchandise exported or imported. Traditionally tonnage and poundage was granted by Parliament to the king for life until the reign of Charles I. Tonnage and poundage were swept away by the Customs Consolidation Act of 1787. Charles I's first Parliament, known as the Useless Parliament, broke with tradition and granted the king tonnage and poundage for a year rather than life out of
Net tonnage adjust economically, since tonnage is the basis for satisfying manning regulations and safety rules. Tonnage is also the basis for calculating registration fees and port dues. One of the Convention's goals was to ensure that the new units "did not differ too greatly" from the traditional GRT and NRT units. Both NT and GT are obtained by measuring ship's volume and then applying a mathematical formula. Net tonnage is based on "the moulded volume of all cargo spaces of the ship" while gross tonnage is based on "the moulded volume of all enclosed spaces of the ship". In addition, a