A more thorough explanation:

Definition: Registered tonnage refers to the volume of a vessel that is officially measured and recorded for taxation purposes. It is also known as register tonnage.

Example: If a ship has a registered tonnage of 10,000 tons, it means that the volume of the ship available for commercial use is 10,000 tons. This measurement is used to determine the taxes that the ship owner must pay.

Explanation: Registered tonnage is an important measurement for ship owners because it determines the amount of taxes they must pay. The higher the registered tonnage, the higher the taxes. For example, a ship with a registered tonnage of 20,000 tons will pay more taxes than a ship with a registered tonnage of 10,000 tons. This measurement is also used to determine the maximum cargo capacity of a ship.