A marine VHF radio is still the single most reliable way to call for help on the water. Unlike a mobile phone, it does not depend on network coverage, it lets the Irish Coast Guard and every other vessel in range hear you at once, and — with one button on a DSC set — it can send your identity and position automatically.
This guide explains, in plain English, what marine VHF is, the licence and operator’s certificate you need to use one legally in Ireland, how DSC and MMSI fit in, how to choose between a fixed and a handheld set, and exactly how to make a distress call when it matters most.
What is marine VHF?
VHF stands for Very High Frequency — the band of radio set aside by international agreement for short-range communication at sea. It is a channel-based system: the band is split into numbered channels, each with a set job. Some are for distress and calling, some for talking ship-to-ship, and some are reserved for the Coast Guard.
A VHF unit is a transceiver, meaning it both transmits and receives. Range is essentially line of sight, so the higher your aerial, the further you reach. A small handheld might manage a couple of nautical miles boat-to-boat, while a yacht with a masthead aerial can reach a Coast Guard station perhaps 40–50 nautical miles away.
Do you need a licence to use VHF in Ireland?
Yes — and it is really two separate things that people often mix up:
- An operator’s qualification — the Short Range Certificate (SRC). This belongs to a person and is earned with a short course and exam. It certifies that you know how to operate the radio and follow the correct distress procedures.
- A Ship Radio Licence (Ship Station Licence). This belongs to the vessel. Any boat, whatever its size, that carries a radio transmitter — fixed or handheld — must hold one.
The Ship Radio Licence is issued through the Department of Transport’s online licensing system (run by the Maritime Radio Affairs Unit). It gives your vessel a call sign — Irish pleasure craft carry an EI callsign followed by four digits — and an MMSI number. All transmitting equipment on board, including radar, an EPIRB or AIS, should be listed on the licence at no extra charge. The licence currently costs in the region of €100; always check the current fee on the official system before applying.
Common misconception: it is the boat that is licensed, not the individual radio. A handheld VHF still requires the vessel to hold a Ship Radio Licence, and the set may only be operated by an SRC holder (or by someone under their supervision). Using an unlicensed radio, or operating one without a certificate, is an offence.
DSC and MMSI explained
DSC stands for Digital Selective Calling — a digital paging layer that sits on top of ordinary voice VHF. It works a little like texting: at the push of a button, a DSC set can alert every DSC radio in range, or “ring” one specific vessel by its number.
Its most important job is distress. Press and hold the guarded Distress button and the set sends a digital alert on Channel 70 (reserved solely for DSC) containing your vessel’s identity and — if the radio is connected to GPS — your exact position, before you follow up with a spoken Mayday on Channel 16.
An MMSI (Maritime Mobile Service Identity) is a unique nine-digit number — think of it as a phone number for your boat. Irish MMSIs begin with 250. You need one for DSC to function, and also for an AIS transceiver and a modern EPIRB. You obtain it from the authority that issues your radio licence.
Leisure boats use the simpler, less expensive D-class DSC; compulsory-fit commercial vessels use A-class. DSC is not legally required on a private leisure boat, but it is strongly recommended — and every new fixed VHF sold in the EU is already DSC-capable. You can compare our PLB & AIS units if you are building out a DSC and AIS set-up.
Choosing a VHF radio: fixed vs handheld
Most boats end up with one of each, but they do different jobs.
| Fixed-mount VHF | Handheld VHF | |
|---|---|---|
| Power | Up to 25 W — far greater range | Typically 5–6 W — a few miles at best |
| Aerial | Connected to a proper masthead or rail aerial | Short built-in aerial, held at deck level |
| Power source | Wired to the boat’s battery | Self-contained rechargeable battery |
| Best for | The primary radio on any cruising or fishing boat | Backup, the tender or liferaft, small open boats |
A fixed-mount set is the mainstay of any seagoing boat: higher power, a proper aerial and usually DSC, and it can share GPS position with a chartplotter. A handheld is portable and self-contained, with waterproof and even floating models available — invaluable as a backup, in the liferaft grab-bag, or on a small open boat. Some handhelds now include DSC and built-in GPS too.
Buying tip: choose a CE-marked set with a Declaration of Conformity, and make sure it carries the M1/M2 (marina) channels used in Ireland and the UK. Radios made for other markets, such as the US, can use different channel plans and may not be legal to use here. Browse our full range of VHF radios, including trusted names such as Icom.
Antennas and range
Because VHF is line of sight, the aerial matters more than raw wattage. Height wins every time: mounting the antenna as high as you can — a masthead on a yacht, a good pole or rail mount on a powerboat — does more for your range than any increase in power ever will.
A quality antenna, well mounted with sound cable and connectors and kept free of corrosion, is one of the best-value upgrades on the boat. See our marine antennas, including Glomex.
How to make a distress call (Mayday)
Channel 16 (156.800 MHz) is the international distress, urgency and safety calling channel. When you are at sea, keep your set on Channel 16 — use the Dual Watch facility if you also want to monitor a working channel at the same time.
On a DSC set, send the DSC distress alert first (press Distress, then Send), then make the spoken call on Channel 16 in this order:
- “MAYDAY, MAYDAY, MAYDAY”
- “This is [boat name, spoken three times]“, followed by your call sign
- “MAYDAY [boat name]“, call sign
- Your position — latitude and longitude, or a bearing and distance from a known point
- The nature of the distress (for example, “holed and taking on water”)
- The assistance you need
- The number of people on board
- Any other useful information — liferaft launched, EPIRB deployed, and so on
Then release the button and listen. The Coast Guard should be the first to answer; other vessels wait until they are sure a Coast Guard station has heard you.
Three levels of call, in order of severity: Mayday — grave and imminent danger to life or vessel; Pan-Pan — urgency, a serious situation that is not yet life-threatening; Sécurité — safety, such as a navigation or weather warning.
Channel etiquette and everyday use
- Keep Channel 16 for calling and emergencies. Make contact, then switch to a working channel — 6, 8, 72 or 77 — to have your conversation.
- End a transmission with “Out” — never “over and out”; the two words mean opposite things.
- Listen to Channel 16 whenever the vessel is in use; it is a condition of your licence.
- Do not use marine VHF ashore, or for non-ship chat — both are prohibited by your licence.
- For a radio check, call the Coast Guard on a working channel rather than tying up Channel 16.
On the inland waterways: Coast Guard radio stations also cover Lough Ree (Channel 62) and Lough Derg (Channel 61), and broadcast a dedicated inland lakes forecast — a VHF is just as worthwhile on the Shannon lakes as on the coast.
VHF and your wider safety kit
VHF is your first line of communication, but it works best as part of a layered system. When you are beyond VHF range, or in the water and separated from the boat, a 406 MHz beacon takes over — an EPIRB registered to the vessel, or a PLB carried on your lifejacket. AIS makes you visible to nearby shipping.
Together with flares, a liferaft and properly serviced lifejackets, these form the safety net the Irish Coast Guard relies on. If you carry an EPIRB, make sure it is registered — see our guide on registering your EPIRB.
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Getting qualified — the SRC course
The Short Range Certificate (SRC) is a short course — typically around a day and a half including exams — accredited by the Department of Transport and recognised worldwide. It covers DSC operation, distress and safety procedures, EPIRBs, SARTs and NAVTEX, with hands-on practice on real radios.
Courses run around the country, including in Galway and Mayo. Offshore sailors venturing well beyond the coast may go on to the Long Range Certificate (LRC), while professional crew on SOLAS vessels take the ROC or GOC. For most leisure boaters, the SRC is all you need.
Frequently asked questions
Do I need a licence to use a marine VHF radio in Ireland?
Yes. You need two things: an operator’s Short Range Certificate (SRC), held by a person, and a Ship Radio Licence, held by the vessel. Any boat carrying a radio transmitter — including a handheld — must hold the licence.
What channel do I use in an emergency?
Channel 16 is the international distress and calling channel for voice; DSC distress alerts go out automatically on Channel 70. Keep your set on Channel 16 whenever you are afloat, using Dual Watch if you also want to monitor a working channel.
What is DSC and do I need it?
Digital Selective Calling lets your radio send a one-button digital distress alert — with your identity and GPS position — and call other vessels by their MMSI number. It is not legally required on a private leisure boat, but it is strongly recommended, and every new fixed VHF sold in the EU already has it.
What is the range of a marine VHF radio?
VHF is line of sight, so range depends mainly on aerial height. A handheld may reach only a couple of nautical miles boat-to-boat, while a yacht with a masthead aerial can reach a Coast Guard station perhaps 40–50 nautical miles away.
Should I choose a handheld or a fixed-mount radio?
A fixed-mount set is the primary radio on any seagoing boat — more power, a proper aerial and usually DSC. A handheld is best as a portable backup, in the liferaft or on a small open boat. Many boaters carry both.
Can I use a marine VHF radio on land?
No. Marine VHF may only be used afloat for ship-to-ship and ship-to-shore-station communication. Using it ashore, or for non-ship conversations, is prohibited under your licence conditions.
Licensing details, fees and procedures are set by the Department of Transport and can change. This guide is for general information — always confirm the current requirements with the official Irish maritime radio licensing system before you buy or operate a set.