SOS calls are not used very often, but they are an essential part of maritime safety procedures. Typically, they are issued by the commander or leader of a boat when there is a threat to the safety of people on board, a threat to the vessel, or during times of catastrophic weather conditions. The language for communicating SOS calls is English.

The Procedure

When a person or vessel is in danger and needs emergency assistance or rescue, an SOS call is made by VHF DSC station (distress alert). This call takes priority over other calls. The last known position of the vessel and the time in UTC is given when the SOS call is made. Whenever the radio station is connected by GPS, this information is sent automatically. It can also be manually sent and should be updated every four hours.

If you have to send an SOS message, you should first use DSC on Channel 70. Wait for an acknowledgement from the coast station. If this doesn't come within 15 seconds, move to VHF on Channel 16 and send the SOS message again.

Make sure the message you send is clear and easy to understand. Here are some examples:

• "Mayday, Mayday, Mayday"
• "This is (identify your station and its name)" - repeat this three times before saying "Mayday"
• MMSI and the name of your station (1x)
• "My position is (give the position of your vessel using latitude and longitude or AZIMUT, as well as the distance from any static object that is visible)
• "I am sinking / on fire / etc." - explain in one sentence what danger you are in
• "I have (summarize the situation briefly)" - you should include the number of crew members and other important information that could be helpful for the search and rescue teams
• "I require immediate assistance" - ask for immediate help
• "Over" - finish your message with this and wait for an answer

You should switch to Channel 16 while waiting for the answer to your SOS call. If there is no answer, the call will automatically be redialed at intervals of three and five minutes.