How to use a VHF radio

Marine band VHF radio is the most common communication system used at sea and on the UK’s inland waterways. It refers to the frequency range between 156.0 and 162.025 MH and is a good way for vessels to communicate with each other and with the shore.

VHF radio is always installed on large ships and is also on most seagoing smaller vessels and other boats used in land. The regulations are slightly different on rivers and lakes, however, the basics remain the same. VHF can be used for a number of purposes, including calling for rescue service and communicating with harbours, locks, marinas and bridges.

Nowadays, VHF radios aren’t simply used for basic transmit and receive capabilities. Seagoing vessels will tend to have permanently mounted marine VHF's, which are required to have certification of some level of “Digital Selective Calling" (DSC) capability, to allow a distress signal to be sent with a single button press.

It is important that you're using a VHF radio if you're out on the water, as this is the primary communication used by all of the rescue services at sea. Therefore, it's very good practice to ensure that we're all on the same communication system, making it quick and easy to contact the services if and when they're needed.

Your VHF radio isn't simply for use in emergencies, as all of the harbour authorities and marinas in Britain use these systems to communicate to vessels. So, you would use these communication systems to book a berth for a short stay, to check if the fuel pontoon is open or for mooring advice.

Range
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When it comes to the range of one of these radio systems, the general rule is, if you can see it, then you should be able to contact it. Basically, it's a line of sight radio system, and the waves can be reflected or sometimes blocked by larger objects, such as headland or harbour walls.

Whilst this is usually the case, the range of your radio tends to be affected by the Antenna and the power of the transmitter. Even if you own the best VHF out there, it'll still offer disappointing performance if it's linked to a poor quality or badly installed VHF antenna. You should also remember that the height of the antenna is also a factor that can have an impact on how good your signal is.

Remember, it's the antenna that actually sends and receives the signal, and, as previously mentioned, a VHF radio is a line of sight radio. This means that the higher the antenna, the further the range should be.

The power of your radio also has an impact on the range of your signal. It's relatively simple, the higher the wattage of your device, the further your signal should reach. This doesn’t mean that you should always whack it onto full power straight away. More often than not a lower power will suffice, and using your radio on its highest setting all the time will drain your boat’s battery.

It's wise to start off on a lower power, and if the communication with your target is difficult then simply turn up the power. A higher power level can also help to counter obstacles such as sea conditions or large walls etc.

Handheld and fixed VHF radios
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You're able to opt for one of two options when it comes to installing your VHF radio. These are handheld and fixed models. Both devices work in a similar manner, and both have their advantages and disadvantages. Whilst handheld VHF radios essentially share the same features as their fixed equivalents, they do differ in a number of ways.

One advantage of a handheld VHF radio is that they're smaller and more portable, and they also run using a separate energy source from the rest of the vessel. They also use a separate antenna, and are very useful in an emergency. They do have their disadvantages as well. For example, the handheld radios tend to have a weaker power output and battery life.

Fixed radios have better battery power, and are the more advantageous choice of the two options. Many models are now available with waterproof fascias which allow secure installation in open boats such. On a fixed, or mounted, VHF radio, the controls tend to be larger and easier to use and they also tend to have a large LCD display.

Again, most of the basic radio functions on these two designs are the same, however, the recent advent of Digital Selective Calling (DSC) in fixed radios has now simplified the way in which distress calls are made. Now, if you have a model with this feature, you're able to press a single SOS distress button in the event of an emergency and summon the rescue services.

Using Digital Selective Calling in an Emergency
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A VHF radio that has DSC enabled can be used in an emergency to send an automatic distress message quickly and simply. The user only has to hold the SOS distress button, and the signal is then sent out. These radios are also designed to be connected to a GPS receiver, which means that the digital message won't only include your unique MMSI number (Maritime Mobile Service Identity), but it'll also include your vessel’s current location.

The message that's sent out when using the DSC function, will be transmitted to all of the vessels in your area, as well as the Coastguard, who will then be able to see your boat’s details and other information like your home contact number.

Once the Coastguard has received your message, they will then attempt to contact you through the VHF channel 16. In order to receive this transmission, your VHF radio will have automatically switched to channel 16 as soon as it's sent the distress message. And, to ensure you're heard, the VHF radio will continue to automatically send the distress message every four minutes until the Coastguard responds.

In order for you to specify your distress message most DSC type VHF radios will allow you to attach a number of ‘headers’ or titles to your message. This means you can send the message out with the word SINKING or MAN OVERBOARD attached. In doing this you're able to help the Coastguard understand the nature of your SOS before they've even contacted you.

VHF Licensing
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Every marine VHF radio, requires the user and the vessel to hold a license. The license for the vessel is very similar to a tax disc that you'd have on your car. In sorting this license, you're also able to obtain your MMSI number for a DSC VHF radio. The license is free of charge and you are able to get it from OFCOM.

In order to show that they've been properly trained to use a VHF radio, every user will be required to have an operator’s license, which is similar to a driving license. VHA radio courses are available around the country and are run by the Royal Yachting Association.

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