46 U.S. Code Part J - Measurement of Vessels
Part J contains provisions that apply to the measurement of a vessel to determine its tonnage. Tonnage is a measurement of a vessel’s volume and is used for international, customs, and regulatory purposes. This part implements the 1969 International Convention on Tonnage Measurement of Ships and provides a framework for phasing in the international system as the method of measuring ships domestically, to establish uniformity in ship measurement. The availability of an alternate domestic regulatory system of measurement is continued so that the application of domestic laws will be preserved in order that vessels engaged in domestic commerce will not be adversely affected.