What sound signal should a vessel nearing a bend or an area where other vessels may be obscured make?

When a vessel is nearing a bend or an area where it may not be able to see or be seen by other vessels, it is required to make one prolonged blast. This sound signal is used to alert other vessels of its presence and intention to maneuver safely in an area where visibility may be compromised. The prolonged blast serves as a warning that helps to prevent collisions in confined or obstructed waterways, thereby enhancing safety for all vessels.

The sound signal of one prolonged blast is particularly important in situations where the visibility of other vessels is limited, ensuring that all parties are aware of each other's presence and intentions. This signal is consistent with the International Regulations for Preventing Collisions at Sea (COLREGs), which establish guidelines for sound signaling to promote safe navigation.