What sound signal indicates a vessel in distress?

The signal indicating a vessel in distress is a series of prolonged blasts on the whistle or horn. This practice is part of the internationally recognized distress signals that are vital for ensuring safety at sea. Prolonged blasts are distinctive and can effectively attract the attention of nearby vessels or shore stations.

The use of sound signals is essential because they convey a clear message about the situation of the vessel. In emergency situations, it's crucial for surrounding vessels to recognize that assistance is required, and the prolonged sound pattern achieves this by standing out among other navigational sounds. This method is widely understood in maritime communication protocols, ensuring that all ships, regardless of their origin, can interpret the distress signal accurately.

The other signal options render different meanings or purposes. One short blast, for example, typically indicates a turning maneuver and does not suggest distress. Similarly, three short blasts represent a specific maneuvering indication of a vessel reversing or backing up, while a continuous ringing of the bell is a sound often used to indicate a vessel at anchor or, in some contexts, to signal a warning but does not explicitly indicate a distress situation.