When is a vessel considered to be overtaking another vessel?

A vessel is considered to be overtaking another vessel when it is coming up from a direction more than 22.5 degrees abaft her beam. This is defined in the International Regulations for Preventing Collisions at Sea (COLREGs).

The term "abaft the beam" refers to being behind the measurement line that extends perpendicularly from the ship's beam (the widest part of the vessel). When a vessel approaches from a direction that is more than 22.5 degrees behind the beam, it is deemed to be overtaking. This distinction is crucial because it indicates that the overtaking vessel is not on a collision course with the other vessel, and thus, the responsibility for avoiding a collision largely falls on the overtaking craft.

Understanding this rule helps ensure proper navigation practices and avoidance of maritime accidents. It is important to recognize that while speed can influence interactions between vessels, the determining factor for overtaking status is the relative angle of approach rather than just speed alone.