In restricted visibility, what is the main purpose of sound signals?

• A. To indicate weather conditions.
• B. To entertain the crew.
• C. To signal navigational status only during daylight.
• D. To indicate a vessel’s presence and, where appropriate, its intention to maneuver; signals help others anticipate actions in poor visibility.

Answer: (D)

In restricted visibility, sound signals are the primary way vessels communicate when you can’t rely on sight. They serve two things: that your vessel is present and, when appropriate, what you intend to do. By signaling your presence and your intended maneuver, you help other vessels anticipate actions, adjust their own course or speed, and reduce the risk of collision. These signals are standardized and understood at sea, and they supplement radar and other navigation aids. They’re not about weather, entertainment, or limited to daylight.