What type of signal must a vessel make when leaving the dock on Inland waters?

When a vessel is leaving the dock on inland waters, it is required to make one prolonged blast. This signal is intended to alert other vessels in the area of its movement, ensuring safety and preventing collisions. The use of a prolonged blast serves as a clear indication that the vessel is maneuvering and may be entering the navigation channel or crossing the path of other vessels.

Understanding the context of sound signals is essential in maintaining navigational safety; each type of signal has specific meanings associated with vessel movement. In this instance, the prolonged blast communicates the vessel's departure, allowing others to prepare or adjust their navigation accordingly. This practice is part of the Colregs (International Regulations for Preventing Collisions at Sea) which outline standard signaling protocols.