When vessels are in sight of each other, what is the primary rule they must follow?

The primary rule that vessels must follow when in sight of each other is encapsulated in Rule 8: Actions to avoid collision. This rule is fundamental in maritime navigation as it emphasizes the need for vessels to take positive action to avoid collisions when they can visually detect one another. It requires vessels to assess their situations, including speed, proximity, and maneuverability, clearly interpreting each other's intentions based on their actions.

Rule 8 mandates that vessels must not only be aware of one another but also must anticipate potential collision scenarios and take appropriate measures to avoid them. This may involve altering course or speed as necessary to maintain safety. The focus is on effective communication and situational awareness while navigating in a shared environment.

While other rules, such as Rule 2 (Responsibility), provide a broader framework regarding the overall responsibilities of vessels at sea, Rule 8 provides specific guidance on actions to be taken in situations where vessels can see each other. Rules 14 and 19 address particular scenarios—head-on situations and restricted visibility, respectively—but do not cover the general principle of avoiding collisions when vessels are in visual contact.