What is the appropriate response if another vessel signals a prolonged blast while your vessel is approaching?

When another vessel signals a prolonged blast, this is typically an indication of their intention or a warning about their presence or maneuvering. The correct response is to signal back with the same sound. This action, also known as responding to a sound signal, serves to acknowledge the communication and indicates that you have heard and understood the initial signal.

Sound signals are a crucial part of navigational safety, especially in situations with limited visibility or congested waters where vessels may not be able to see each other clearly. By responding with the same sound, you are confirming that you are aware of the other vessel's presence and are maintaining situational awareness.

While options like speeding up, changing direction, or making a safety stop could be considered in some scenarios, they do not address the need for communication between vessels. The focus during such encounters should be on maintaining clear communication to avoid collision or misunderstandings. Thus, signaling back with the same sound is the most appropriate and responsible action in this situation.