How to Use a Marine VHF Radio: Channels, Calls, and Etiquette

A marine VHF radio is the most reliable way to communicate on coastal waters, but only if you know the channels, call procedures, and etiquette. This guide explains how VHF works, how to make routine and distress calls, and the common mistakes that can compromise safety.

Main Explanation

What it is

A marine VHF radio is a two-way radio system operating in the very high frequency band between 156 and 174 MHz, designated by the International Telecommunication Union as the official maritime mobile band. Transmitter power is limited to 25 watts, giving a maximum line-of-sight range of about 62 miles (100 km). It is the primary means of communication on coastal waters, allowing instant contact with other boats, marinas, bridges, and the U.S. Coast Guard. Although not required on recreational boats under 65.5 feet long, it is widely considered the single most important radio system a boater can buy. In the United States, recreational boaters do not need a license for a VHF marine radio when operating domestically.

Using a VHF radio correctly means understanding three things: the channel plan, the standard call procedures, and the unwritten rules of radio etiquette. Channels are assigned for specific purposes—distress, calling, working, and weather—and using the wrong channel can delay help or interfere with critical traffic.

Why it matters

Cell phones are unreliable on the water. They lose signal a few miles offshore, are easily damaged by water, and do not broadcast to nearby vessels or rescue authorities on emergency frequencies. A VHF radio, by contrast, is designed for the marine environment and is monitored by the Coast Guard and other vessels. When you key the microphone on Channel 16, every nearby boat and shore station with a radio on that channel hears you. That broadcast capability is what makes VHF indispensable in an emergency.

There is also a legal dimension. If you have a VHF radio turned on, you must maintain a watch on Channel 16. In U.S. Coast Guard District I waters (northern New Jersey to Canada), urgent marine information broadcasts, such as storm warnings, are announced on Channel 16. Missing those broadcasts because you were on the wrong channel or had the volume down can put you in harm’s way.

How it works

Marine VHF channels are standardized internationally, with some regional variations. The most important channels for recreational sailors are:

• Channel 16 (156.8 MHz): International distress, safety, and calling frequency. Use it for Mayday, Pan-Pan, and Sécurité calls, and for initial contact with another station before switching to a working channel.
• Channel 9: A secondary calling channel, often used for non-commercial recreational traffic to reduce congestion on 16.
• Working channels: Channels such as 68, 69, 71, 72, and 78A (in the U.S.) are used for routine ship-to-ship and ship-to-shore communication after initial contact.
• Weather channels: Dedicated NOAA Weather Radio channels provide continuous forecasts and warnings. Most VHF radios can receive these, and many have an alert feature.

Call procedures follow a clear hierarchy. A Mayday call is used only when there is grave and imminent danger to life or vessel and immediate assistance is required. A Pan-Pan call signals an urgent situation that is not yet life-threatening. A Sécurité call is used to broadcast navigation safety messages, such as a hazard to navigation or a weather warning. Routine calls are simply the name of the station you are calling, spoken three times, followed by your own station name and the channel you are using.

Etiquette is about efficiency and clarity. Listen before transmitting to avoid interrupting ongoing traffic. Keep messages brief and use standard prowords. Use low power (1 watt) for close-range communication to reduce interference. Always identify your vessel by name or call sign. Never use VHF for private conversations or non-marine business.

How to do it

Here is a practical walkthrough for a typical coastal passage:

1. Pre-departure check: Turn on the VHF radio, set squelch so background noise just disappears, and verify you can hear Channel 16. Perform a radio check on a working channel or Channel 9, not on 16.
2. Monitor Channel 16: Keep the radio on Channel 16 whenever underway. If you need to use a working channel, use dual-watch or tri-watch if available, or periodically return to 16.
3. Make a routine call: To call a marina, for example, press the transmit button and say: ‘Seaside Marina, Seaside Marina, Seaside Marina, this is sailing vessel Windward, Channel 16.’ Release and listen. When they respond, agree on a working channel, switch, and conduct your business.
4. Send a distress call: If you are in grave danger, switch to Channel 16, press transmit, and say slowly: ‘Mayday, Mayday, Mayday. This is sailing vessel Windward, Windward, Windward. Mayday. Position: [latitude and longitude or bearing and distance from a known point]. Nature of distress: [fire, sinking, medical emergency]. Number of persons on board. We require immediate assistance. Over.’ Release and listen for a response. Repeat if no answer.
5. Monitor weather: Before departure and periodically during the passage, listen to NOAA Weather Radio or your local marine weather broadcast. Do not rely solely on VHF for weather; cross-check with official forecasts.

When not to do it

VHF is not a universal communication tool. It is line-of-sight, so its range is limited by antenna height and terrain. For offshore passages beyond about 25–60 miles from shore, VHF may not reach the Coast Guard or other vessels. In those situations, you need an MF/HF radiotelephone, a satellite phone, or an EPIRB. VHF is also not a substitute for professional training. A radio cannot teach you collision avoidance, heavy-weather tactics, or medical care. And while VHF can receive weather broadcasts, it is not a weather routing service; for complex passages, consult a professional weather router or use dedicated weather forecasting tools. Finally, do not use VHF for non-marine communication or as a replacement for a certified marine surveyor when evaluating a boat’s seaworthiness.

Visual

Common Mistakes

Not monitoring Channel 16 when the radio is on

Many sailors turn on the VHF but then switch to a working channel or turn the volume down. If you have the radio on, you must maintain a watch on Channel 16. Missing a distress call or urgent marine information broadcast can delay rescue or put you in danger. Use dual-watch or tri-watch if you need to monitor a working channel, but always keep 16 as the priority.

Using a cell phone as the primary communication tool

Cell phones fail exactly when you need them most—offshore, in rough weather, or after a knockdown. They do not broadcast to nearby vessels or the Coast Guard on emergency frequencies. A VHF radio should be your primary means of communication on the water; a cell phone is only a backup.

Making routine calls on Channel 16

Channel 16 is for distress, safety, and initial calling only. Conducting routine conversations on 16 congests the emergency frequency and can block a Mayday call. After establishing contact, immediately switch to a working channel. Use Channel 9 as a calling channel for non-emergency traffic where available.

Giving an incomplete distress call

In an emergency, people often forget to give their position, the nature of distress, or the number of people on board. Without a position, rescuers cannot find you. Practice the Mayday format: Mayday three times, vessel name three times, position, nature of distress, number of persons, and ‘over.’ Speak slowly and clearly.

Using high power for close-range communication

VHF radios typically have a high (25 W) and low (1 W) power setting. Using high power for a call to a marina a mile away creates unnecessary interference for other stations. Use low power for close-range communication and switch to high power only when needed for distance or in an emergency.

Relying on VHF weather broadcasts as your only forecast source

VHF weather channels provide continuous NOAA broadcasts, but they are not a substitute for detailed passage planning. Forecasts can change, and VHF reception may be limited. Always cross-check with official marine weather services, and for longer passages, use multiple sources and consider professional weather routing.

Safety Note

A VHF radio is a critical safety tool, but it is only one part of a broader safety framework. Digital tools, reference platforms, and communication devices complement—never replace—proper training, physical checks, and human judgment. Before every departure, test your VHF radio, check the antenna and connections, and confirm you can receive Channel 16 and weather broadcasts. Always cross-check critical data such as weather, tides, and navigation with official sources, not just a single app or radio broadcast. Never use a tablet or phone as your only navigation tool; keep paper charts and a handheld compass as backups. Take a certified boating safety course and practice emergency procedures, including Mayday calls, man-overboard drills, and abandon-ship protocols. Follow the International Regulations for Preventing Collisions at Sea (COLREGS) and all local maritime regulations. If you are venturing more than a few miles offshore, carry an EPIRB or personal locator beacon, and consider a satellite phone or MF/HF radio for long-range communication. Your VHF radio is only as good as your ability to use it under stress—practice regularly and keep the radio within reach of the helm.