What does the term "sound signal" refer to in COLREGs?

The term "sound signal" in the context of the COLREGs (International Regulations for Preventing Collisions at Sea) specifically refers to acoustic signals that vessels use to communicate their actions or intentions. These sound signals, which can be in the form of whistles, horns, or bells, are essential for maritime safety, particularly in situations where visibility is restricted, such as fog or heavy rain.

For instance, different horn blasts convey specific meanings—such as the intention to overtake another vessel or to indicate that a vessel is anchored. By using these sound signals, mariners can prevent collisions and ensure all vessels are aware of each other's movements in a navigable area. Understanding the function and purpose of these acoustic signals is crucial for compliance with maritime regulations and for maintaining safety on the water.