Which sound signal is typically used for distress?

A continuous fog horn is the internationally recognized sound signal for distress. It conveys the presence of an urgent situation that requires immediate attention. The sound is loud and prolonged, making it easily identifiable over long distances and adverse weather conditions. This makes it effective for communication in maritime environments, where visibility may be limited.

Other sound signals, such as a single bell, short blasts, or a whistle blast, do not convey the same level of urgency or distress. A single bell typically indicates a specified action on a vessel, while short blasts and whistle blasts are used for signaling maneuvers or intentions rather than indicating that a vessel is in distress. Therefore, the continuous fog horn serves as a crucial alert mechanism that draws attention and prompts a response from nearby vessels or shore authorities, emphasizing its importance in emergency situations at sea.