When is a skipper authorized to transmit a 'MAYDAY' (Socorro) distress call on VHF Channel 16, and what standard information must it contain?

1. Only in situations of grave and imminent danger to the vessel or life requiring immediate assistance; contains: MAYDAY (x3), vessel name/callsign, MMSI, position, nature of distress, number of persons on board, and immediate assistance required
2. Whenever the vessel runs out of drinking water in calm weather
3. When the engine fails inside a designated marina slip while securely moored
4. To report a minor traffic delay approaching the harbor entrance