Marine VHF Radio Basics

A marine VHF radio is one of the most important safety devices onboard any boat. It allows you to communicate with marinas, nearby vessels, bridges, locks, coast guard services and emergency responders. Unlike a mobile phone, a VHF radio broadcasts to every vessel within range, making it the primary communication system for distress situations at sea.

This guide explains how VHF radio works, how marine VHF radio works on a boat, the purpose of the most important VHF channels, how to make routine calls, emergency calls, and how to communicate professionally using standard marine radio protocol, VHF radio protocol and proper VHF radio etiquette.

Important Safety Note

• Use clear and short transmissions.
• Never make false distress calls.
• Keep emergency channels free.
• Obtain the required radio operator licence where applicable.
• Always monitor Channel 16 while underway whenever possible.

What is a Marine VHF Radio?

Marine VHF (Very High Frequency) radio is a short-range communication system operating between 156 and 174 MHz. Depending on antenna height, radio power, terrain, vessel position and weather conditions, communication range is typically between 5 and 30 nautical miles.

Every vessel within radio range can hear your transmission when using a standard voice channel, making VHF much more suitable than a mobile phone during emergencies. A mobile phone connects only to the number you call. A VHF call can alert nearby vessels that may be able to help immediately.

How Does VHF Radio Work?

VHF stands for Very High Frequency. A marine VHF radio sends and receives short-range radio signals over marine channels allocated for safety, navigation and vessel communication. When you press the Push-To-Talk button, your voice is converted into a radio signal and transmitted through the antenna. Other VHF radios tuned to the same channel and within range can hear the message.

The most important thing to understand is that VHF is usually a line-of-sight communication system. The signal travels best when antennas can “see” each other without land, high cliffs, buildings or the curvature of the earth blocking the path. That is why a masthead antenna on a sailing yacht normally gives better range than a handheld radio used from the cockpit.

How Does VHF Marine Radio Work on a Boat?

A marine VHF radio works by connecting the skipper and crew with other vessels, marinas, harbour authorities, coast guard services and rescue stations. On most boats, the fixed VHF radio is connected to the boat battery, an external antenna and often GPS or chartplotter data for DSC distress alerts.

In normal use, you select the correct channel, listen first, press the PTT button, speak clearly, then release the button to receive a reply. In an emergency, a DSC-equipped radio can also send a digital distress alert with the vessel’s MMSI and GPS position, followed by a voice MAYDAY call on Channel 16.

Main Components of a VHF Radio

Fixed vs Handheld VHF Radios

Most Important Marine VHF Channels

Channel 16

Channel 16 (156.800 MHz) is the international distress, safety and calling channel. Every vessel should monitor this channel whenever practical.

Channel 16 is used for:

• Mayday distress calls
• Pan-Pan urgency calls
• Sécurité safety broadcasts
• Initial contact between vessels
• Calling marinas or coast stations before switching channels

Once contact has been established, both stations should immediately switch to a working channel.

Channel 70

Channel 70 is reserved exclusively for Digital Selective Calling (DSC). Voice communication is strictly prohibited on this channel.

A DSC distress alert automatically transmits:

• Vessel MMSI number
• GPS position if connected
• Time of distress
• Nature of distress if selected

Working Channels

Working channels are used after initial contact has been made on Channel 16 or another local calling channel. Different countries may allocate working channels differently, so always follow local regulations and marina instructions.

Marina Communications

Most marinas publish their preferred VHF working channel in pilot books, nautical charts or on their websites.

1. Call the marina on Channel 16 or the published calling channel.
2. Wait for a response.
3. Switch to the requested working channel.
4. Provide your boat name, length and berth request.

Marina Split, Marina Split,
this is sailing yacht Aurora.

Requesting berth for one night.

Over.

Marine Radio Protocol: Basic VHF Call Format

Marine radio protocol is the standard way of speaking on VHF so that messages are short, clear and easy to understand. Good VHF radio protocol reduces confusion, keeps emergency channels clear and helps other vessels understand exactly who is calling, who is being called and what action is needed.

For most routine calls, use this simple structure:

1. Say the name of the station or vessel you are calling.
2. Repeat the called station name if needed.
3. Say “this is” followed by your vessel name.
4. State your request or reason for calling.
5. Say “over” when you expect a reply.
6. Move to a working channel if the call started on Channel 16.

Marina Split, Marina Split,
this is sailing yacht Aurora.

Requesting berth for one night.

Over.

VHF Radio Protocol: Words and Phrases Every Skipper Should Know

Routine Ship-to-Ship Calls

When calling another vessel, state the vessel name, identify yourself and request a channel change.

Blue Horizon,
Blue Horizon,
Blue Horizon,

This is Sea Breeze.

Request switch to Channel 72.

Over.

Interactive VHF Call Simulator

Use this simulator to practice the structure of a VHF call. It does not transmit anything. It only helps crew members understand what information must be said and in which order.

Distress Call — MAYDAY

MAYDAY is used only when there is immediate danger to life or the vessel. Examples include sinking, fire, serious collision, person overboard not recovered, abandonment or another immediate life-threatening emergency.

MAYDAY
MAYDAY
MAYDAY

This is sailing yacht Aurora.
Call sign 9A1234.
MMSI 238123456.

Position:
43 degrees 30 minutes North
016 degrees 20 minutes East.

We are taking on water.

Require immediate assistance.

Four persons onboard.

Over.

Urgency Call — PAN-PAN

PAN-PAN is used for urgent situations that are serious but not immediately life-threatening.

• Engine failure in a dangerous position
• Disabled vessel
• Medical emergency requiring advice
• Loss of steering
• Rig damage without immediate danger to life

Safety Broadcast — SÉCURITÉ

SÉCURITÉ is used to broadcast navigational or weather safety information.

• Floating containers
• Navigation hazards
• Derelict vessels
• Severe weather warnings
• Unlit buoys or damaged navigation marks

How to Use the Radio Correctly

1. Turn on the radio.
2. Adjust volume.
3. Set squelch until background noise disappears.
4. Select the desired channel.
5. Listen before transmitting.
6. Press and hold the PTT button.
7. Wait half a second before speaking.
8. Speak clearly and slowly.
9. Release the PTT button when finished.
10. Wait for a reply.

VHF Radio Etiquette

VHF radio etiquette means using the radio in a disciplined, professional and respectful way. Marine VHF is a safety system, not a chat room. Poor radio etiquette can block urgent calls, confuse other vessels and create unnecessary risk.

• Listen before transmitting so you do not interrupt another call.
• Keep transmissions short, especially on Channel 16.
• Speak slowly, clearly and directly into the microphone.
• Do not interrupt distress, urgency or safety traffic.
• Avoid unnecessary conversation and move to a working channel after initial contact.
• Use standard marine terminology instead of slang.
• Never use offensive language or make false distress calls.
• Always identify your vessel by name.
• Use “Over” when expecting a reply and “Out” when the conversation is finished.
• Use low power for nearby routine calls when possible to reduce interference.

Marine Radio Rules Every Beginner Should Know

Marine radio rules vary by country, but the basic safety principles are similar in most cruising areas. Before operating a VHF radio, check local requirements for operator certificates, vessel radio licences, channel plans and DSC/MMSI registration.

Common Mistakes

Interactive VHF Maintenance Checklist

VHF Licence Practice Questionnaire

This popup quiz helps skippers and crew practice the type of knowledge usually needed for a VHF/SRC radio operator certificate: distress procedure, DSC, Channel 16, Channel 70, urgency calls, safety broadcasts, radio checks, MMSI, GPS, PTT discipline and standard phraseology.

Frequently Asked Questions

Conclusion

A marine VHF radio is an essential safety device for every boat. Understanding the purpose of each channel, knowing how to make routine and emergency calls, and following proper radio etiquette improves communication and can save lives in an emergency.

Practice using your VHF radio regularly so you can operate it confidently when it matters most. Before any bareboat charter, especially in Croatia, also verify whether your skipper license and VHF radio certificate are accepted. Read the full guide here: Accepted Foreign Boat Licenses in Croatia.