What does it mean for a vessel to be "underway"?

A vessel is considered "underway" when it is not anchored, tied to shore, or aground, meaning it is not immobilized. This term indicates that the vessel has some degree of movement or is free to navigate, either drifting or moving under its own power. This is an important distinction in boating regulations, as certain rules apply specifically to vessels that are underway, including navigation lights requirements and rules of the road.

In contrast, if a vessel is docked at a marina, permanently stationed, or moving at a speed of less than 1 knot, it does not meet the definition of being underway, as these situations imply that the vessel is secured or not active in navigation. Understanding what it means for a vessel to be underway is crucial for safe boating practices and for complying with maritime laws.