In the hierarchy of vessels according to Rule 18, which type of vessel comes first?

In the hierarchy of vessels as specified by Rule 18 of the International Regulations for Preventing Collisions at Sea (COLREGs), the "Not Under Command" vessel comes first. This classification is critical as it outlines the responsibilities that vessels have when they encounter each other on the water.

A vessel that is not under command is unable to maneuver as required, typically due to engine failure or other operational limitations. This status necessitates that other vessels give way to them to prevent collisions and ensure the safety of all parties involved. In the context of the collision avoidance rules, the recognition of this priority helps maintain order and safety on the waterways by ensuring vessels in distress receive the necessary consideration from others.

Other categories, like "Constrained by Draft," "Sailing," and "Fishing," follow it in the hierarchy. While these vessels also have specific right-of-way statuses, they are not as prioritized as a vessel that is declared "Not Under Command." Understanding this hierarchy is essential for safe navigation and compliance with maritime regulations.