For those in peril on the sea

Simrad VHF Marine Radio

How do we call for help?

We all hope it will never happen to us but if you spend time at sea on any craft, you have to accept that things can sometimes go wrong. The ability to deal with problems afloat is a fundamental part of seamanship and seafarers have a long history of self-reliance.

However, there may come a time when you need outside assistance, whether from nearby vessels or the Search and Rescue (SAR) authorities. When events conspire against you, you need to be able to summon help quickly and effectively.

Boat on fire
It’s not just bad weather that presents a danger at sea: fire on board a vessel is often devestating and calls for a quick distress alerting method

There are a whole host of different methods for alerting people to your distress at sea. For commercial vessels over 300grt or those that carry 13 or more passengers, the distress alerting equipment carried is governed by the Global Maritime Distress and Safety System (GMDSS). In simple terms, it says that these vessels must carry at least two independent means of transmitting a distress signal.

GMDSS does not apply to small commercial vessels or recreational craft but that does not mean we should ignore the advice, as the sea presents exactly the same hazards to any vessel. The area in which a vessel operates, be it coastal waters or further offshore, helps to guide the type of equipment carried. However, distance from the shore does not always equate to a higher probability of something going wrong and coastal waters are where the vast majority of rescue incidents occur.

In this first article, I am going to look at our primary method of calling for help at sea- the marine radio.  In subsequent articles, I will look at some of the other options available, both recommended and desirable.

The first choice: marine radio

Marine radio has been in existence for over a century and forms the foundation of communication at sea. In coastal waters, where most recreational sailing takes place, as well as a lot of commercial activity, Very High Frequency (VHF) radios are the most common method of communication.


Simrad RD68 VHF radio
My Simrad RD68 VHF training radio is an early example of a DSC capable radio. Although an older design, it has all the same DSC capabilities as more modern radios

How far can we communicate?

VHF radio is essentially a ‘line of sight’ system, so range is governed by the height of the transmitting and receiving antennas. On the average cruising yacht, with the antenna mounted at the masthead, a VHF set can achieve a maximum range of around 30-40 miles, if transmitting to a large shore based antenna (as used by the coastguard).

This range is normally sufficient for the majority of coastal sailors and VHF radios are primarily used for routine voice communication between vessels and from vessels to shore stations. They are also our primary source of weather and safety information when at sea, delivered through the coastguard’s regular Maritime Safety Information broadcasts.

Calling for help

Above all else though, a VHF radio gives us the ability to call for help when we are in distress*, in the form of the traditional ‘Mayday’ voice message on Channel 16. Being a broadcast system, anyone listening on Channel 16 (which should hopefully be all vessels and the coastguard) and within range, will hear the distress message.

This broadcast feature of VHF radio is one of its major advantages over a mobile phone- everyone will hear your call for help, as opposed to just the person at the other end of the phone. At sea, your nearest help is often another vessel, so the benefits of this method are obvious. Other advantages of VHF over a mobile phone include greater battery life and the ability for SAR services to ‘home in’ on a VHF transmission. The biggest development in recent years though has been DSC.

What is DSC?

Although sometimes still referred to as a ‘new’ system, Digital Selective Calling (DSC) has been in existence since 1999 and forms a crucial part of GMDSS. It allows ‘bursts’ of digital information to be sent and each VHF-DSC set is given a unique Maritime Mobile Service Identity (MMSI), a bit like a phone number.

DSC has many advantages, the primary one being the ability to instantly send a digital distress alert. Normally in the form of a red, protected button, when pushed this feature allows the user to quickly send an automated distress alert, which will be received by all DSC capable VHF sets within range, including the coastguard.

The digital distress alert


Red Distress Button
The red distress button, normally protected in some way, either by a flap or sliding cover, is the giveaway for a DSC capable VHF radio

This digital distress alert contains a small amount of information: the vessel’s unique MMSI, the time the alert was sent, the nature of the distress (if selected) and the vessel’s position. The position can be entered manually, in the form of a lat/long but this is laborious and prone to error.

Nearly all vessels these days carry some form of GPS or chart plotter, which can be interfaced with your VHF to automatically include your position with any distress alert (even some handheld GPS sets can provide this output). This set up is strongly recommended, as your position is by far and away the single most important bit of information in a distress situation. There are even some fixed VHF sets on the market now that contain their own internal GPS for this purpose.

After pushing the ‘red button’ to send a digital distress alert, if there is time, you should still send a follow-up voice Mayday message. This will contain useful additional information and help the Search and Rescue authorities make a better assessment of the situation. Just as importantly, it also ensures that any vessel not fitted with a VHF-DSC set (and there are still plenty out there), is still aware you are in distress and they can offer assistance if appropriate.

Handheld VHF-DSC radios

Icom M91D
My Icom IC-M91D handheld DSC-VHF. Note the lat/long displayed on the screen, courtesy of the in-built GPS

All new fixed VHF sets sold in the UK have to be DSC capable and in the last few years, a number of VHF-DSC handheld radios have also come onto the market. This new generation of handheld radios, admittedly still comparatively expensive, are a great option for those that don’t have a fixed set, such as small powerboat users or sea kayakers. They all have the red distress button function, as well as a built-in GPS, which will provide your position and can also be used as an aid to navigation.

Icom M91D distress button
On the rear of the Icom M91D is a red distress button, exactly as you would find on a fixed VHF set

It makes sense…

The UK Coastguard (MCA) strongly recommends that all vessels fit a DSC capable VHF radio and with fixed sets now available from as little as £100, there really is no excuse not to fit one. When fitting a new VHF-DSC radio to a vessel, you need to apply to OFCOM for a unique MMSI number, which you must program into the set.

Lastly, it is important to note that in a distress situation, anyone can send a distress alert and/or message and this is something all boat owners and skippers should brief crew and passengers on. Having a dedicated Mayday procedure card next to the radio is a very sensible idea, as this means anyone can send a distress message if necessary.

Mayday Procedure Card
A copy of the Mayday Procedure card I have mounted prominently next to the VHF radio on board my own boat. I always draw people’s attention to this the first time they come on board

Get some training

For those people who intend to regularly use a VHF radio which is voluntarily fitted on board a British Flagged vessel, it is a legal requirement to hold the Short Range Certificate. This certificate of competence is awarded after a short written and practical assessment, normally preceded by a 1-day classroom course. These courses are run on behalf of the MCA by RYA training centres across the UK.

* The definition of a ‘distress situation’ is very specific and the ability to send a distress alert so readily now, means it is even more important to know when to use one. The official definition is when ‘a vessel, vehicle, aircraft or person is in grave and imminent danger and immediate assistance is required’. Examples would be things like sinking, fire or a man overboard but there is no exhaustive list and each situation must be judged by those involved.

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