Which action is required of Boat A while overtaking Boat B in darkness or reduced visibility?

In the context of navigating in darkness or reduced visibility, using the correct maneuvers is crucial for safety. When Boat A is overtaking Boat B, the standard maritime practice is for the overtaking vessel to maneuver in a way that avoids confusion and ensures safety.

In such situations, Boat A is required to overtake Boat B in a manner that clearly indicates its intentions and keeps a safe distance. This typically involves going around Boat B, allowing for a clear passage while reducing the risk of collision, especially when visibility is compromised. This action adheres to the maritime 'rules of the road,' which dictate that overtaking vessels should pass safely and clearly without impeding the other vessel's navigation.

The other actions, such as sounding a horn continuously or signaling Boat B to move aside, can create unnecessary confusion and are not the prescribed methods for safe overtaking. Decreasing speed to idle may not effectively facilitate safe passage and could potentially lead to hazardous situations if Boat A cannot maneuver effectively in the given circumstances.