How to Use a VHF Radio for Distress and Routine Calls

A VHF marine radio is the single most important piece of safety communication equipment you can carry aboard a recreational boat. Unlike a cell phone, it operates on dedicated marine frequencies that are continuously monitored by the U.S. Coast Guard and other vessels, and it provides direct, real-time contact for both routine coordination and life-threatening emergencies. This guide explains how to use a VHF radio correctly for distress and routine calls, from basic channel selection to digital selective calling (DSC), so you can communicate clearly and get help when it matters most.

Main Explanation

What it is

A VHF marine radio is a two-way radio that transmits and receives on very high frequency (VHF) FM channels between 156 and 174 MHz, the band designated internationally for maritime mobile use. Transmitter power is limited to 25 watts, which gives a typical line-of-sight range of roughly 5 to 25 nautical miles depending on antenna height and terrain. The system is standardized globally, so a VHF radio works the same way whether you are sailing a small daysailer or a cruising yacht, and it is not tied to any particular boat brand, sailing school, or equipment manufacturer. In this context, “using a VHF radio” means operating a standalone safety and communication tool that follows international protocols for hailing, working, and distress traffic.

Modern VHF radios often include Digital Selective Calling (DSC), a feature that sends a digital distress alert with your vessel’s identity and, if connected to a GPS, your position at the press of a button. This is part of the Global Maritime Distress and Safety System (GMDSS), which the U.S. Coast Guard supports through its Rescue 21 network.

Why it matters

At sea, clear communication can be the difference between a minor inconvenience and a fatal outcome. Sailors face information overload from apps, forums, and outdated manuals, and conflicting advice can lead to hesitation exactly when seconds count. A VHF radio cuts through that noise: it gives you a direct line to nearby vessels, marinas, bridges, and rescue authorities. The Coast Guard continuously monitors VHF Channel 16, the international distress and calling frequency, and many coastal stations also monitor Channel 9 for hailing. A cell phone cannot replicate this because it is not monitored by other boats, has limited offshore coverage, and is not designed for wet, rough conditions. The stakes of poor communication at sea are high, and a VHF radio is the most reliable, inexpensive tool you can buy to reduce that risk.

How it works

VHF operation is built around a small set of channels and procedures. Channel 16 is reserved for distress, safety, and initial hailing. Channel 9 is an alternative hailing frequency in many U.S. waters. Working channels such as 68, 69, 71, and 72 are used for routine ship-to-ship and ship-to-shore conversations after contact is established. Weather channels provide continuous NOAA marine forecasts. DSC radios add a dedicated distress button that transmits a digital alert containing your Maritime Mobile Service Identity (MMSI) number and, if interfaced with a GPS, your latitude and longitude. To use the radio effectively, you monitor Channel 16 when not actively communicating, listen before transmitting, keep calls brief, and use standard prowords like “over” and “out” and the phonetic alphabet for spelling names or positions.

How to do it

Here is a practical walkthrough for a typical coastal passage. Before departure, obtain an MMSI number and program it into your DSC radio, connect the radio to your GPS or chartplotter, and test the unit with a radio check on a working channel or an automated radio check service. While underway, keep the radio on and set to Channel 16. To call a marina or another vessel, first listen to ensure the channel is clear, then say the name of the station you are calling three times, followed by “this is” and your vessel name three times. For example: “Harbor Master, Harbor Master, Harbor Master, this is Sailing Vessel Meridian, Meridian, Meridian, over.” Once they reply, agree on a working channel, switch to it, and conduct your business. In an emergency, if you have DSC, press and hold the red distress button for the required time; the radio will send your position and identity. Then, on Channel 16, make a voice Mayday call: say “Mayday, Mayday, Mayday,” state your vessel name and position, describe the nature of the distress, the number of people aboard, and any other critical information, then say “over” and listen. Speak slowly and clearly, and repeat the call if you do not receive an immediate response.

When not to do it

A VHF radio is not a substitute for proper training, navigation, or weather judgment. Do not rely on it as your only means of getting help in remote offshore areas beyond VHF range; for ocean passages, carry an MF/HF radiotelephone, satellite phone, or EPIRB. Do not use VHF for idle chatter or non-maritime conversations, as this congests safety channels and may violate regulations. Do not attempt to use a VHF radio to navigate or obtain detailed weather routing; it provides voice weather broadcasts but not the graphical, real-time data of dedicated weather services. Finally, if you are unsure about radio procedures, take a certified marine radio course rather than learning only from online articles or manuals.

Visual

The table below compares a VHF marine radio with other communication and distress options available to recreational sailors.

Common Mistakes

Not monitoring Channel 16 while underway

Many sailors turn the radio off or leave it on a working channel, missing distress calls or hails from other vessels. The consequence is delayed response to emergencies and missed navigational coordination. Keep the radio on and set to Channel 16 whenever you are not actively using another channel.

Using Channel 16 for routine conversations

Channel 16 is for distress, safety, and initial hailing only. Using it for idle chatter blocks emergency traffic and can result in fines. Hail on Channel 16 or 9, then immediately switch to a working channel such as 68, 69, 71, or 72.

Not knowing how to state your position in a distress call

Rescuers cannot help if they do not know where you are. In a Mayday, give latitude and longitude from your GPS, or a bearing and distance from a known landmark or buoy. Practice reading your position before you need to do it under stress.

Relying on a cell phone instead of a VHF radio

A cell phone is not monitored by the Coast Guard or nearby boats, has limited offshore range, and is easily damaged by water. The consequence is that your distress call may go unheard. Use VHF as your primary communication and keep the cell phone as a backup only.

Not registering an MMSI or connecting GPS to a DSC radio

A DSC distress alert without a registered MMSI and GPS position is far less useful to rescuers. The Coast Guard’s Rescue 21 system can locate a DSC alert only if the radio has a valid MMSI and is connected to a GPS. Obtain an MMSI, program it, and test the GPS interface.

Speaking too fast or using non-standard language

Rapid, unclear speech leads to misunderstood positions and instructions. Speak slowly, use standard prowords (“over,” “out,” “roger”), and spell critical words with the NATO phonetic alphabet (Alpha, Bravo, Charlie, etc.).

Safety Note

A VHF radio is a powerful safety tool, but it is only one part of a broader safety framework. Always cross-check critical data—weather, tides, currents, and navigation—with official sources such as NOAA weather radio, the U.S. Coast Guard, and local maritime authorities. Never use a phone or tablet as your only navigation device; keep paper charts and a handheld compass as backups. Take a certified safety course from a recognized organization such as the U.S. Coast Guard Auxiliary, U.S. Sailing, or the American Sailing Association, and practice making distress calls in a controlled setting. Follow the International Regulations for Preventing Collisions at Sea (COLREGS) and all local maritime regulations. Before every departure, test your VHF radio, check the antenna and battery, and confirm that your DSC radio has a valid MMSI and GPS connection. In an emergency, if you have DSC, press the distress button first, then follow with a voice Mayday on Channel 16. Keep a continuous listening watch and be prepared to relay information to rescue authorities.