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
Gross tonnage a universal tonnage measurement system. Various methods were previously used to calculate merchant ship tonnage, but they differed significantly and one single international system was needed. Previous methods traced back to George Moorsom of Great Britain's Board of Trade who devised one such method in 1854. The tonnage determination rules apply to all ships built on or after July 18, 1982. Ships built before that date were given 12 years to migrate from their existing gross register tonnage (GRT) to use of GT and NT. The phase-in period was provided to allow ships time to adjust economically, since tonnage is