Which of the following best describes a vessel "underway"?

A vessel is considered "underway" when it is not at anchor, nor is it made fast to the shore. This definition is crucial within maritime navigation and safety as it sets a clear distinction between various states of a vessel. When a vessel is underway, it can be actively making way through the water or simply drifting, but it must not be immobilized by anchoring or mooring.

This definition has significant implications for the application of the COLREGs, especially in understanding the responsibilities of vessels in terms of navigation and collision avoidance. A vessel not at anchor or made fast to the shore signifies that it has the capability to maneuver and respond to other traffic, which is essential in preventing collisions.

In contrast, a vessel that is anchored, aground, or docked at a marina is not considered underway, which places them under different regulations regarding navigation and traffic conduct. Understanding this distinction is essential for safe seamanship and compliance with maritime regulations.