Which of the following is a requirement of Rule 18 when vessels are in sight of one another?

Answer: C — Vessels must take actions to avoid collisions

Rule 18 of the COLREGs outlines the responsibilities of vessels when they are in sight of one another and specifically addresses the required actions to avoid collisions. It establishes the obligation for vessels to take positive action to avoid dangerous situations and ensure safe navigation. The requirement to take actions to avoid collisions is crucial because it acknowledges that visibility creates opportunities for vessels to be aware of each other’s presence and to interact accordingly. It emphasizes the importance of making navigational decisions based on situational awareness to prevent accidents, which is a fundamental principle in maritime safety. This rule signifies that when vessels can see each other, they must use their judgment to determine the best course of action to maintain safety, such as altering speed, changing course, or taking other measures to prevent collisions. Therefore, the emphasis is on proactive navigation and communication when vessels are close enough to assess their relative positions and intentions.