What does a prolonged blast of 4-6 seconds signify when boating?

A prolonged blast of 4-6 seconds is recognized in the boating community as a warning signal. This signal is particularly important in situations where visibility is limited, such as fog, heavy rain, or nighttime, to alert other vessels of your presence and location. It helps prevent collisions by communicating to other boaters that you may be approaching or navigating through a potentially dangerous area.

The other choices do not accurately represent the standard boating signals. Starting the engine does not require a specific sound signal, and while reducing speed is a common practice in certain situations, it is not indicated by a prolonged blast. The intent to pass on the starboard side is typically signaled using a different, shorter blast sequence. Therefore, the prolonged blast serves as a crucial safety measure on the water.