VHF - The Basics of Marine and Safety Communications

When most people think of marine electronics, the "VHF" is probably one of the first things that comes to mind and it should also be the first item you invest in when outfitting a boat or upgrading your electronics. However, for many boaters their marine communications requirements extend far beyond VHF range. For those individuals, Medium Frequency/High Frequency Single Sideband (MF/HF-SSB) should be considered.

You will find VHF marine radios on board most all vessels throughout the world. From 1100’ Super Carriers right down to the 20’ fishing boat. Unquestionably, the marine VHF is the workhorse of marine communications. Typical uses of the VHF range from distress and safety communications, marine navigation advisories, current and forecast weather reports, contacting other vessels, connecting into the phone system for phone calls thorough a marine operator, right down to getting a slip reservation at your local marina and just about everything in-between. The most important aspect however, is that all marine VHF’s are designed and built to use specific internationally agreed upon frequencies regardless of manufacturer. This provides mariners anywhere in the world common frequencies to be able to communicate easily. Well . . . Almost!


That being said, there are now (3) sets of VHF marine frequency schemes in use in the world today (International, Canadian, and U.S.) Most all VHF’s today have either a dedicated switch (the easiest way) or a menu item that allows for switching between these sets of channels. Fortunately the main distress and safety frequencies Channels (6, 13, 16, 67, and 70) are standardized across all three allowing for critical communications regardless of the setting on your radio. Nonetheless, the radio operator must be aware of which frequency scheme is in use in the area of the world he is sailing if he expects to communicate effectively.

Safety Afloat

For those who own or use a boat, the marine radio is probable considered to be the primary piece of safety equipment onboard. The use of common frequency allocations and proper marine communications procedures further enhance that safety. This adds up to significant peace of mind for all of us who venture away from the dock.

There are basically (4) categories of marine communications. : "Distress", "Urgency", "Safety", and "Routine." Within these categories are the (3) internationally recognized emergency signals used for voice communications:

  1. MAYDAY - (pronounced "MAY-DAY"): This is the distress signal and is only used to indicate that the vessel is threatened by grave and imminent danger and requires immediate assistance.
  2. PAN-PAN - (pronounced "PAHN-PAHN"): This is the urgency signal and is used when the safety of the vessel or a person is at risk.
  3. SECURITE - (pronounced "SAY-CURE-A-TAY"): This is the safety signal and is used to advise others about important navigation or weather warnings that may impact the safety of other vessels.

Emergency situations are broken down into three categories; distress, urgency and safety. Any of these calls should be made on channel 16 since the USCG as well as many other coast stations guard this frequency 24/7.

It is good to note here the order of priority for these signals:

  1. Safety (SECURITE) have precedence over any and all routine communications.
  2. Urgent communications (PAN-PAN) Take precedence over safety communications.
  3. Distress traffic (MAYDAY) Takes precedence over all other categories of communications.

All of the above voice calls are typically made on channel 16 (156.800 MHz) since the USCG as well as many public and private coast stations guard this frequency 24/7.

If you hear a distress call, cease all transmission. Unless you are involved in the rescue or providing assistance, no one else is allowed to transmit on the frequency. You should, however, listen and follow the situation until it is evident that assistance is being provided. Normal transmissions may resume after the Rescue Coordinator has released the frequency to routine traffic ("Silence Fini").

The rule-of-thumb here is simple: If you hear distress, urgent, or safety traffic - Cease your own transmissions and listen!

Who’s Right, Who’s Wrong - Does it Really Matter?

There seems to have always been some contentious discussions on the use of the MAYDAY distress signal and when its use is appropriate. To further stir up the debate, I offer the following citations from the United States Code of Federal Regulations:

The FCC states:

47 CFR 80.314 Distress signals.
(a) The international radiotelephone distress signal consists of the word MAYDAY, pronounced as the French expression ``m'aider''.
(b) These distress signals indicate that a mobile station is threatened by grave and imminent danger and requests immediate assistance.
(Emphasis mine)

47 CFR 80.327 Urgency signals and messages.
(a) The urgency signal indicates that the calling station has a very urgent message to transmit concerning the safety of a ship, aircraft, or other vehicle, or the safety of a person. The urgency signal must be sent only on the authority of the master or person responsible for the mobile station.
(Emphasis mine)

The Coast Guard states:

46 CFR 121.510 Recommended emergency broadcast instructions.
(a) Emergency Broadcast Instructions.
(1) Make sure your radiotelephone is on.
(2) Select 156.8 MHz (channel 16 VHF) or 2182 kHz. (Channel 16 VHF and 2182 kHz on SSB are for emergency and calling purposes only.)
(3) Press microphone button and, speaking slowly-clearly-calmly, say:
(i) "MAYDAY-MAYDAY-MAYDAY" for situations involving Immediate Danger to Life and Property;
(Emphasis mine)
(ii) "PAN-PAN" for urgent situations where there is No Immediate Danger to Life or Property.

As you can see there is some conflict between the two. Since the FCC regulates the use of radios in the U.S. and the USCG regulates which vessels are required to carry them, I will side with the FCC in this argument.

The Bottom Line.... If you have lost someone over the side, no one is going to make an issue out of whether you use the correct emergency signal. Obviously the most important thing is to get the help you need to deal with the situation. And believe me, either one of these emergency calls, MAYDAY or PAN-PAN, should bring you all the help that you need and then some.

The Radio Watch

Another issue that raises a lot of questions is the "Radio Watch." The short answer is if you are underway you must maintain a listening watch on your radios.

47 CFR 80.310 Watch required by voluntary vessels.
Voluntary vessels not equipped with DSC must maintain a watch on 2182 kHz and on 156.800 MHz (Channel 16) whenever the vessel is underway and the radio is not being used to communicate. Noncommercial vessels, such as recreational boats, may alternatively maintain a watch on 156.450 MHz (Channel 9) in lieu of VHF Channel 16 for call and reply purposes. Voluntary vessels equipped with VHF-DSC equipment must maintain a watch on 2182 kHz and on either 156.525 MHz (Channel 70) or VHF Channel 16 aurally whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with MF-HF DSC equipment must have the radio turned on and set to an appropriate DSC distress calling channel or one of the radiotelephone distress channels whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with a GMDSS-approved Inmarsat system must have the unit turned on and set to receive calls whenever the vessel is underway and the radio is not being used to communicate.

While not explicitly stated in the regulation, if your vessel is not equipped with MF/HF-SSB the requirement to maintain a watch on 2182.0 kHz is not required.

So for the purposes of a voluntary VHF marine radio installation:


The Final Step

So once you have selected, purchased, and installed your VHF radio, you need to learn how to use it properly. Read the manual, learn the controls and their functions, and practice proper radio procedure. You also should take the time to train your crew (family, friends, or whomever) on its use. If you are the only one that knows how to use your VHF marine radio and you’re the one that is injured, unconscious, or has taken the big swim . . . Oh Well!


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