Basics on Acoustic and Radio Distress Signals

In case an emergency occurs offshore and you require assistance, you will have to use distress signals. This can be vital especially for cruisers who spend their vacation for off the coasts. In this article, I will briefly outline how to use radio and acoustic distress signals.

For centuries, sailors in distress had to use visual distress signals to draw attention and request assistance. Today, most sailors rely on radios and communication systems that have long proved to be much more efficient than flags and flares under most circumstances. The correct use of acoustic distress signals is essential for every cruiser.

Let’s briefly talk about the means of communication first. Ambitious dinghy sailors that carry a radio and cruisers that stay in coastal areas often carry a simple radio system such as “Very High Frequency” (VHF) Radios. VHFs reach about 40 miles to the coast and a maximum of 10 miles between two boats.

Alternatives are “Medium Frequency” (MF) Radios; they reach impressive 200 miles, but they are much more expensive. Therefore, normally only cruisers use them. There are legal regulations for both, VHFs and MFs – the boat needs to be registered and hold a license and the user of the radio must have a license, too. Many modern radios come with integrated, fully automatic distress signal functions.

Modern EPRIBs for Emergency Calls

A more recent radio system is the “Emergency Position Indicating Radio Beacon” or EPRIB. This device is very expensive, but common among cruisers with international ambitions. It emits distress signals that can be received by satellites associated with the “Global Maritime Distress and Safety System” GMDSS. The distress signal includes information about the precise position of the vessel. EPRIBs are registered with the name of the owner and the watercraft it is used on, which can be crucial for rescue endeavors.

Emergency calls and distress signals are transmitted on channel 16 (156.8 Hz) or 2186 Hz. Keep in mind that the distance values I mentioned above for VHF and MF radios are rather guidelines. The distance a radio signal can travel depends on the charge of the ionosphere, to put it into simplified words: At day, high frequencies transmit further, low ones often badly. At night, especially at clear nights, high frequencies get lost in space, whereas the distance of low frequencies travel further than during the day.

There are essentially only three acoustic signals that you should remember, but it is important to use them correctly. The “SOS” is classic, but had its golden days in the time of Morse code communication. It sounds like “… --- …” followed by a break; then the signal is repeated until a confirmation is received.

Mayday and Pan Pan: How to use them

Much more important is the PAN PAN signal. It is repeated three times and indicates an emergency and request for assistance; it is NOT used when the boat is sinking. In this case, you would use the MAYDAY signal, which is the only distress call that has higher priority than the PAN PAN signal.

It indicates that a vessel is in a state of urgent distress and requires immediate assistance. To use the MAYDAY call correctly, apply it like this: “MAYDAY, MAYDAY, MAYDAY. This is “name of the vessel”, “name of the vessel”, “name of the vessel”. MAYDAY “name of the vessel”. Our position is “concise description of the position, as precise as possible”. Here you can also specify what type of emergency you struggle with, in case that the conditions allow longer communication. Over.

If you receive any of the mentioned distress signals, you are obliged by law to offer any help you can. Reversibly, every vessel that receives a distress signal from you has to offer assistance.

Further Reading

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Wikipedia on Distress Signals

Wikipedia on the International Code of Signals

Department of State's Travel advice - crucial information for your safety

Display of all International Maritime Signal Flags