When is a vessel considered "underway"?

Answer: C — When it is not grounded, anchored, or attached to shore

A vessel is defined as "underway" when it is not anchored, moored, or aground. This means that it is free to navigate through the water and is actively capable of maneuvering. Being underway indicates that the vessel is in a state where it can respond to navigational controls and is not restricted or fixed in place by any mooring or grounding conditions. In maritime terminology, it is critical to understand this concept for determining the vessel's responsibilities under the COLREGs, as different rules apply when a vessel is underway compared to when it is stationary, such as when anchored, moored, or in dry dock. A vessel that is in dry dock is physically out of the water and not capable of sailing, while one that is anchored or moored is also not navigating but secured in one place. By recognizing the definition of "underway," operators can better assess their navigational duties and the implications of their vessel's status on the water.