What is the term for a pushing vessel and a pushed barge that are rigidly connected?

The term for a pushing vessel and a pushed barge that are rigidly connected is a "composite unit." This designation is used within maritime regulations to describe a specific configuration where a vessel, typically a tug or a similar craft, and its barge or towed structure operate as a single navigational entity. This type of arrangement offers better maneuverability and stability compared to a simple towing operation because the two parts are connected in such a way that they behave as one unit in the water.

The distinction of a composite unit is vital in the context of navigation and compliance with the COLREGs, as it informs the lighting and shape requirements for the unit. For example, composite units must display specific lights that indicate their configuration to other vessels, enhancing safety on the water.

Other options like "connection unit," "tow unit," and "linked unit," do not have established meanings in maritime terminology concerning the COLREGs. While they may loosely describe similar concepts, they are not the recognized terminology used internationally to denote the particular arrangement of a pushing vessel and a pushed barge that are rigidly connected. Thus, understanding the terminology and its proper application is crucial for safe navigation practices.