Which signal would indicate that a vessel is reversing course in international waters?

The signal indicating that a vessel is reversing course in international waters is represented by three short blasts. These blasts serve as a communication tool to convey the vessel's maneuvers to others nearby, promoting safety and reducing the risk of collisions. Specifically, three short blasts signal that a vessel is backing up or reversing its direction.

In maritime operations, sound signals are a crucial part of navigation, especially in situations where visibility may be limited. The use of three short blasts ensures that other vessels are aware of the maneuver, allowing them to take appropriate actions to avoid any potential hazards.

The other choices represent different actions or intents; for example, one short blast typically indicates turning to starboard, while one prolonged blast is often used in restricted visibility to indicate a vessel is underway. Two prolonged blasts signify a vessel that is engaged in a specific maneuver but does not directly indicate reversing course. Understanding these signals is vital for safe navigation in international waters.