What sound signal indicates the presence of a power-driven vessel?

The sound signal that indicates the presence of a power-driven vessel is one prolonged blast. This signal is used to communicate that a vessel is approaching or is navigating in a manner that may affect other vessels in the area. In particular, one prolonged blast serves as a warning on busy waterways, allowing other boaters to be aware of the power-driven vessel's presence.

Understanding the context of sound signals is crucial in boating safety as these auditory cues help prevent collisions and enhance situational awareness on the water. Each type of sound signal has a specific meaning, and recognizing them is essential for all boaters to navigate safely and responsibly.