09/14/2026
In maritime navigation, a prolonged blast is a horn or whistle sound that lasts for four to six seconds. It is used as a warning signal or to communicate a vessel's movements and status to other boats.
Common Meanings and Uses
Leaving a dock: Sounds one prolonged blast to show the vessel is casting off or getting underway from a berth.
Blind bends: Warns hidden or oncoming traffic when approaching a sharp turn or obstructed channel.
