What does a vessel do to signal that it is altering its course?

A vessel signals that it is altering its course by making a short blast of sound. This auditory signal serves a crucial purpose in maritime communication, particularly in situations where visual cues may not be sufficient or clear. A short blast, typically lasting about one second, is recognized universally in maritime practice. It conveys the vessel's intention to change direction, ensuring that nearby vessels are aware of the maneuver, which enhances safety on the water by reducing the risk of collisions.

Other signaling methods, such as flashing lights or changing the color of navigation lights, are not standard indicators for course changes and serve different functions in maritime navigation and safety protocols. For instance, flashing lights may indicate various situations or alerts, but they do not communicate a course alteration specifically. Similarly, changing navigation light colors is typically reserved for indicating specific statuses of the vessel, such as whether it is underway, at anchor, or engaged in fishing.