What sound signal should be given when overtaking another vessel on the port side in a narrow channel?

When overtaking another vessel on the port side in a narrow channel, the appropriate sound signal is two prolonged blasts followed by two short blasts. This signal is used to indicate the intention to overtake and ensure that both vessels are aware of the maneuver being undertaken.

The use of two prolonged blasts indicates that you are maneuvering with the intention to overtake the other vessel on its port side, which is essential for maintaining safety and avoiding collisions in tight or narrow waterways. The additional two short blasts serve to reinforce the maneuver and provide clarity about the action being taken.

The specific nature of sound signals is standardized internationally, and understanding these can significantly enhance communication between vessels and help prevent misunderstandings that might lead to accidents. It is crucial in navigation, especially in narrow channels where space is limited and maneuvering is complex.