Using a VHF Radio: The Basics for Boaters

The marine VHF radio is the most important communication tool on most boats. It lets you call for help in an emergency, talk to harbours, bridges and locks, receive weather and safety broadcasts, and coordinate with other vessels. Yet many boaters feel nervous about using it, unsure of the procedure or worried about saying the wrong thing.

This guide covers the essentials: how VHF works, the channels you need to know, what DSC does, and the simple procedure for making a clear, correct call. With a little practice, using the radio becomes second nature.

How Marine VHF Works

VHF stands for Very High Frequency. Marine VHF radios operate on a set of internationally agreed channels reserved for maritime use. The signal travels essentially in a straight line, so your range depends largely on the height of your aerial and that of the station you are calling. Typical boat-to-boat range is a handful of nautical miles, while boat-to-shore range can be greater because coast stations have tall aerials.

Most VHF radios are either fixed sets, wired to a masthead or deck aerial and the boat’s power, or handheld, which are portable and useful as a backup but have shorter range. In many countries you need a radio operator’s certificate to use marine VHF, and the set itself may need to be licensed.

Channels You Need to Know

VHF has many channels, but a few are essential.

• Channel 16 is the international distress, safety and calling channel. Keep a listening watch on it, use it to make initial contact, then move to a working channel to continue.
• Channel 70 is reserved exclusively for DSC (Digital Selective Calling) and is not used for voice.
• Working channels are used for routine conversation once you have made contact on 16. Marinas, harbours and other services each have designated channels.
• Weather and safety broadcasts are transmitted on specific channels by coastguard and rescue authorities; note the ones for your area.

Never hold ordinary conversations on channel 16. It must stay clear for distress and initial calls.

DSC: Digital Selective Calling

Modern fixed VHF sets include DSC, which adds a digital layer to the radio. Each DSC set has a unique identity number called an MMSI (Maritime Mobile Service Identity), which you must register.

• In an emergency, lifting the guard and pressing the dedicated distress button sends an automated digital alert on channel 70 to the coastguard and nearby vessels. If the radio is connected to GPS, that alert includes your position.
• DSC also lets you call a specific vessel or station directly using its MMSI, rather than broadcasting to everyone.

DSC dramatically speeds up raising the alarm, because a single button press transmits who you are and where you are. Always follow the DSC alert with a spoken Mayday on channel 16 so rescuers get the full picture.

Making a Call: Basic Procedure

Routine calls follow a simple, predictable pattern. Speaking clearly and following the format keeps the airwaves efficient.

1. Listen first to make sure the channel is free.
2. Call using the name of the station you want, then your own vessel’s name: “Harbour Office, Harbour Office, this is Sea Breeze, Sea Breeze, over.”
3. Wait for a reply. When they answer, they may direct you to a working channel.
4. Switch to the agreed channel and keep your message brief and clear.
5. End each transmission with “over” when you expect a reply, and “out” when the conversation is finished.

Use the phonetic alphabet (Alpha, Bravo, Charlie) to spell out names and difficult words, and speak at a steady pace. Keep transmissions short so others can use the channel.

Radio Etiquette and Good Practice

Good radio discipline keeps the channels usable for everyone, especially in an emergency.

• Keep a listening watch on channel 16 while under way.
• Do not transmit unnecessary chatter or use the radio for idle conversation.
• Never make a false distress or hoax call. It is dangerous and a serious offence.
• Identify your vessel at the start of a call and keep messages concise.
• Lower your radio volume of non-urgent traffic if a distress call is in progress, and stay off the air unless you can help.

Learning to handle the radio confidently is a core skill for any skipper, and in many places a formal radio certificate is required. The boatingexamine course explains VHF procedure alongside the wider safety syllabus, so you understand not just which buttons to press but why the procedure exists.

FAQ

Do I need a licence to use a marine VHF radio? In most countries, yes. Using marine VHF typically requires an operator’s certificate, and the radio equipment itself may need to be licensed. Check the specific rules for your country before transmitting, since operating without the correct authorisation is usually an offence.

What is the difference between channel 16 and a working channel? Channel 16 is the international distress, safety and calling channel, used to raise the alarm and to make initial contact. Once you have reached the other station, you both switch to a working channel to continue the conversation, leaving 16 clear for emergencies and new calls.

What does DSC do that voice radio does not? DSC sends a digital message that automatically includes your identity and, if linked to GPS, your position. In an emergency, one button press alerts the coastguard and nearby vessels instantly, far faster than reading out details by voice. Always follow it with a spoken Mayday for the full details.