When must a vessel take early action to avoid impeding another vessel?

The correct answer is when the other vessel is in a narrow channel. In this situation, the rules under COLREGs emphasize the importance of maintaining safe navigation and minimizing the risk of collisions. Narrow channels are considered high-risk areas where the options for maneuvering are limited. Therefore, a vessel has a responsibility to take early action to avoid impeding the passage of other vessels that are constrained by their draft or navigating in a narrow waterway.

In such scenarios, proactive measures ensure that all vessels can navigate safely and efficiently without creating dangerous situations. By recognizing the importance of prompt action in these contexts, mariners adhere to the navigational rules designed to enhance safety at sea, especially in areas where the risk of collision is heightened due to restricted space and maneuverability.