Final answer:
When coming within a half-mile of another power-driven vessel, boaters must use sound signals to communicate their intentions and prevent collisions.
Step-by-step explanation:
When you come within a half-mile of another power-driven vessel, you must use sound signals to communicate your intentions and avoid collisions. The International Regulations for Preventing Collisions at Sea (COLREGS) provides specific rules for sound signals in different situations.
When coming within a half-mile, you should sound one short blast to indicate your presence. The other vessel should respond with one short blast as well. This exchange signals that both vessels are aware of each other and are taking appropriate action to avoid a collision.
It's important to note that sound signals are just one part of boating safety. Vessels should also maintain a proper lookout, follow navigation rules, and take necessary actions to avoid any risk of collision.