What does a prolonged whistle blast indicate in maritime communication?

A prolonged whistle blast in maritime communication serves as a warning signal to alert other vessels of potential danger or to indicate that there is a situation requiring caution. This sound is particularly important in scenarios where visibility is reduced, such as in fog or other adverse weather conditions, where vessels may not be able to see each other. Under the International Regulations for Preventing Collisions at Sea (COLREGs), a prolonged blast is recognized as a signal of warning.

By understanding this signal, mariners can maintain safety and avoid collisions by being aware of each other’s presence and intentions. This type of communication is essential for ensuring safety on the waterways, as it helps to convey critical information quickly and effectively without the need for visual confirmation.