What does "tonnage" refer to in maritime navigation?

Tonnage in maritime navigation primarily refers to the measurement of a vessel's cargo-carrying capacity. This term is critical in understanding how much weight a ship can safely transport, which influences not only its design and construction but also the operational and regulatory aspects of maritime transportation. Tonnage is often expressed in terms of gross tonnage (the total volume of a ship's enclosed spaces) and net tonnage (the volume available for cargo). This measurement helps determine port fees, safe navigation capabilities, and compliance with various maritime regulations.

In the context of maritime operations, understanding tonnage is vital for efficient logistics planning and ensuring that vessels are not overloaded, which can affect stability and safety during voyages. This measurement is widely used in shipping and trade to establish a ship's capacity for cargo and the potential revenue that can be generated.