The purpose of sound signals in maritime navigation is primarily to communicate a vessel's intentions, especially in conditions of restricted visibility, such as fog or rain. In these situations, visual signals may not be effective or possible, making sound signals crucial for safety. They help other vessels understand the type of maneuvering a vessel intends to make, such as “I am altering my course to starboard” or “I am approaching a bend or fairway where other vessels may be present.” This communication significantly reduces the risk of collisions, as it allows vessels to anticipate each other’s movements.
Other options, while relevant to maritime safety, do not encompass the primary function of sound signals. For instance, indicating a vessel's destination is generally communicated through charts, navigation aids, or radio, rather than sound. Signal distress situations typically rely on different forms of communication, such as distress signals or emergency beacons. Directing vessel movements in busy ports is primarily managed through visual signals and communication with port authority personnel rather than sound signals alone. Therefore, the emphasis on sound signals as a means of conveying intentions in restricted visibility highlights their critical role in ensuring navigational safety.