Which rule applies to vessels in or around restricted visibility?

The correct answer is Rule 19, which addresses the conduct of vessels in restricted visibility. This rule is critical for navigation safety as it establishes the responsibilities of vessels operating when visibility is limited due to factors such as fog, heavy rain, or contrasts in light.

Under Rule 19, all vessels must take appropriate actions to avoid collisions, which usually involves reducing speed, ensuring safe distances from other vessels, and sounding appropriate signals, such as fog signals. The rule specifies that all vessels, including vessels under power and sailing vessels, must navigate with special caution, giving priorities to vessels engaged in fishing or constrained by their draft, as well as providing necessary maneuvers to prevent collisions.

Implementing Rule 19 helps create safer navigation practices in conditions where visibility can drastically alter perception and situational awareness, which is crucial for all mariners. Understanding this rule is vital for officers who are responsible for the safe operation of their vessels, especially under challenging circumstances.

The other rules mentioned do not pertain specifically to situations of restricted visibility, making them unsuitable for this particular context.