What does two short blasts signal in boating communication?

In boating communication, two short blasts typically indicate that the vessel is backing up. This signal is part of a standardized set of sound signals that help boaters communicate their intentions to maintain safety on the water. When a vessel emits two short blasts, it alerts other boaters in the vicinity that the operator intends to reverse their vessel, allowing other boaters to be aware of potential changes in movement and adjust their navigation accordingly.

The other choices represent different signals or intentions that are not related to the two short blasts. For example, signaling to pass on the starboard side involves a different combination of blasts, while warnings about upcoming hazards would typically use a specific sound pattern designed for that purpose. Indicating a left turn also has its own distinct signal. Understanding these sound signals is crucial for effective communication and safety while boating.