In the event of failure of the ship's main and emergency electrical power sources, the Reserve Source of Energy is used to power what?

• A. Main engine fuel system
• B. Navigation lights
• C. The radio installations for distress and safety communications
• D. Air conditioning systems

Answer: (C)

A separate energy reserve is kept to keep essential radio equipment alive if both the ship’s main and emergency power fail. The Reserve Source of Energy is specifically used to power the radio installations for distress and safety communications, so that MAYDAY calls and safety channels remain operational even in a total power outage. This is critical for getting help and coordinating rescue. The main engine fuel system is a mechanical/propulsion-related system, not a safety radio function; navigation lights and other non-essential comforts like air conditioning aren’t the purpose of this reserve power.