What is the term for a vessel being pushed and the pushing vessel when they are rigidly connected?

The term "Composite unit" is used to describe a situation where a vessel being pushed and the pushing vessel are rigidly connected. This classification stems from the fact that when these two vessels are joined together in a fixed manner, they operate as a single unit, thus creating a composite structure that can navigate together.

This term is particularly relevant in the context of navigation and the application of maritime regulations, including the COLREGs, as it affects the vessel’s maneuverability, stability, and the signaling requirements they must adhere to while on the water. The connection creates a scenario where the pushing vessel takes on the responsibility and characteristics of the composite unit as a whole.

In contrast, other terms described in the choices refer to different configurations or relationships between vessels. A "Towed unit" typically describes a scenario where a vessel is being towed but not rigidly connected, which implies a different set of operational and signal requirements. Similarly, a "Barge unit" usually refers to a barge being towed or pushed but does not encompass the rigid connection aspect. The term "Connected vessels" is more general and does not specifically denote the nature of the connection, making "Composite unit" the most accurate and relevant term in the context provided.