What is indicated when a vessel nearing a bend in a narrow channel sounds a signal?

When a vessel nearing a bend in a narrow channel sounds a signal, it indicates there is a risk of collision due to obscured vessels. This situation typically arises because the visibility around a bend is limited, making it difficult for vessels on either side to see each other. The sound signal serves as a warning to other mariners that the vessel is approaching an area where visibility is impaired and that they should be cautious. This is crucial for maintaining safety in navigation, especially in narrow channels where the risk of collision increases dramatically due to the limited field of view and the possibility of unseen vessels.

In typical navigation scenarios, vessels are required to sound signals to communicate their intentions, especially in restricted visibility conditions. By signaling in this context, the vessel is proactively alerting other operators in the vicinity of potential hazards, thereby facilitating safe passage and reducing the likelihood of an accident.