VHF Radio & Phonetic Alphabet

VHF (Very High Frequency) radio is the primary means of communication at sea. Unlike a mobile phone, VHF works ship-to-ship, ship-to-shore, and is monitored by the Coastguard 24/7. In an emergency, a VHF radio can save your life.

In the UK, you need a Short Range Certificate (SRC) to operate a marine VHF radio. This is a legal requirement under the Wireless Telegraphy Act and is administered by the RYA on behalf of Ofcom.

Key advantages of VHF over mobile phones:

• Distress alerting — DSC (Digital Selective Calling) sends an automated distress alert with your position to all nearby vessels and the Coastguard at the press of a button.
• Broadcast capability — You can call all ships, not just one number.
• Works offshore — No cell towers needed.
• Position included — Modern sets with GPS send your lat/long automatically.

The NATO phonetic alphabet is used internationally to spell out letters clearly over radio. Each letter has a specific word to prevent confusion — for example, "B" and "D" sound alike, but "Bravo" and "Delta" do not.

Marine VHF operates on designated channels between 156.0 MHz and 162.025 MHz. Each channel has a specific purpose — using the wrong channel can block emergency traffic.

Standard calling procedure:

1. Check Ch 16 is clear (listen before transmitting).
2. Press and hold the PTT (push-to-talk) button.
3. Say: "[Station name] x3, this is [your vessel name] x3, over."
4. Release PTT and wait for reply.
5. Agree a working channel, then switch.

There are three levels of priority message on VHF. Using the correct one ensures the right response.

The MAYDAY procedure:

1. "MAYDAY, MAYDAY, MAYDAY"
2. "This is [vessel name] x3, callsign [your callsign]"
3. "MAYDAY [vessel name]"
4. "My position is [lat/long or bearing and distance from known point]"
5. "I am [nature of distress, e.g. sinking, fire, crew overboard]"
6. "I require [immediate assistance]"
7. "[Number of persons on board]"
8. "[Any other useful info: vessel description, EPIRB activated, etc.]"
9. "Over"

Good radio discipline keeps the airwaves clear, ensures your message is understood, and keeps everyone safer. Here are the golden rules:

• Listen before you transmit — make sure the channel is clear.
• Think before you speak — plan your message. Be brief and to the point.
• Speak clearly and slowly — hold the mic 5–10 cm from your mouth, speak across it (not into it).
• Use standard phrases:
  • Over — I have finished speaking, I expect a reply.
  • Out — I have finished, no reply expected. (Never say "over and out.")
  • Roger — I have received and understood your message.
  • Say again — Please repeat. (Never say "repeat" — in military use it means fire again!)
  • Copy — I have received your message.
• Keep Ch 16 clear — initial calls only, then switch to a working channel.
• Never use profanity, music, or unnecessary transmissions — it is a legal offence.

MMSI Number: Every DSC-equipped VHF radio has a unique 9-digit Maritime Mobile Service Identity. This is programmed in by a licensed installer and links your radio to your vessel details in the Coastguard database. It is your "phone number" at sea.