Many of us have come to paddling, whether it be kayak, SUP, surf ski, OC1 or OC6, from backgrounds other than traditional boating like power boats or sailing. Because of this you may not be familiar with the venerable marine VHF radio that has been the mainstay of the boating community since 1950. Advances in electronics have shrunk the size and cost of the VHF radio to a small hand held device that can be bought for under $100. For these reasons a handheld marine VHF radio should be in everyone's safety kit.
I hope that you already have a safety kit in your dry bag or PFD vest, if not stop reading this right now and go read Safety Items to Bring on a Paddle article on setting one up. But lets face it, you can only bring so much and those items will only help you in a finite number of circumstances. The VHF radio is your trump card. With it you can call for help from nearby vessels, your harbor patrol, or the Coast Guard no matter how messed up your situation may have gotten. It's like having a search and rescue helicopter in your dry bag, and that is why I call it the most important part of your safety kit.
These days we use our cell phones for everything and you might be thinking that you can just use that instead of shelling out $100 for a VHF radio. If you only bring your cell phone you are making a dangerous mistake. Don't take my word for it, check out this fact sheet from the US Coast Guard. The cell phone is an amazing device that usually does the job it was designed for very well. But the cell phone system was never designed to be used for maritime communication whereas the marine VHF radio was designed exactly for that purpose.
The first problem with your cell phone is its range and coverage. In order to get good range in a radio communication you need three things; a relatively unobstructed path between transmitter and receiver, a large receiving antenna mounted up high, and lots of transmit power. Cell phone towers are expensive to build and your provider will only put them where their customers are, and that is primarily in urban areas, not on open water. So getting an unobstructed path to a tower from open water is problematic. And while the tower has a big antenna mounted high, your cell phone has almost no antenna and you are down at sea level. Your cell phone was designed to use very little transmit power so you can have long conversations on a tiny battery. All of these combine to limit the range and coverage of a cell phone. I have trouble making a call from my phone when I am parked on the cliffs along the ocean! The VHF radio has an antenna (yours may be small-ish, but other boats and the Coast Guard have big ones up high) that radiates 360 degrees around you using up to 6 Watts of transmit power, and you only need to reach the nearest other VHF radio, not a tower in an urban area.
The next problem with your cell phone is that it was designed for a private connection between two people. That boat 100 yards from you that could rescue you in a minute? You are never going to reach them with your cell phone. The VHF radio was designed to use shared channels that everyone monitors. Your distress call will be heard by every VHF radio in range, and they can relay your message to other radios until rescue services can be reached. It is a Coast Guard regulation that all vessels underway with a VHF radio must monitor channel 16 for emergency calls. Even if you can't receive a transmission or hear it faintly, there is a good chance you are being picked up by other vessels with better antennas.
Another problem with your cell phone is that is simply was not made for the harsh marine environment. It can't get wet and it does not float. You can drop your VHF radio into the drink, pick it up and make a call.
Another technology that you might be considering is a Personal Location Beacon or PLB like the Spot device or an EPIRB. These are really cool devices that use satellite communications to receive your GPS location, and then relay that via another satellite to a central server. EPIRBs are big expensive devices and are not practical for paddlers. Devices like the Spot or Fast Find are small and easy to carry. The downside is that these only send your position, and an optional tag that says either 'here I am' or 'rescue me!' you can't talk to a person or reach that nearby vessel. These devices also require a subscription to their service that in the long run will cost a lot more than a VHF radio, even one with GPS built in.
Marine VHF radios have 50 different channels that they can communicate on. Each of these has a role defined by the FCC, and most of them are allocated for government or commercial purposes leaving only seven we can use. Of those, two have reserved uses and the other five are open for anything. The two special ones you want to remember are channels 9 and 16. Channel 16 is reserved for emergency use only. Channel 9 is used for non-emergency use and from there you can arrange with another VHF radio user to move your conversation to one of the other 5 channels available for general use; 68, 69, 71, 72, and 78. All radios have a button that will flip between channel 16 and 9 directly. All radios have a scan feature that will periodically scan channels 16 and 9 for activity and stop on the channel if they hear something. You can add other channels to the scan if you want to. In addition to this all radios have a second receiver for NOAA weather stations. This is extremely useful for getting the current conditions in your area. You can add weather alerts to your scan too. All radios will have a button to change the output power so you can save battery and not overwhelm nearby receivers when making a call, usually between low (1 Watt), medium (2.5 Watts) and high (6 Watts). Make sure you get a radio that goes up to 6 Watts of power.
The two other controls you will use are the volume and squelch. These can be knobs that you turn or they can be up and down arrow keys depending on the radio. Squelch is used to set a receive signal level below which the radio will not enable the speaker, so that you don't hear constant noise. Setting this too low will cause you to hear a lot of static, but setting it to high may block distant signals.
You can use your VHF radio all over the world, however the US, Canada, and other international countries don't exactly agree on the channel frequency bands. There will be a setup button to select between US, Canada, and International.
An example of a basic radio with all the features mentioned above is the Cobra HH350 (shown at top) that sells for $99. Other manufacturers are West Marine, Standard Horizon, ICOM, and Uniden. You can spend more to get additional features like a big screen or longer battery life.
A radio, and so much more...
The VHF radio is a 60 year old analog technology that has been tested by time. But you can teach an old dog new tricks, and now you can get a VHF radio that has built in GPS and a relatively new feature called Digital Select Calling or DSC. This brings the old VHF radio into the digital world.
The built-in GPS acts like a normal GPS giving you your location, time and date, and a compass that will show heading and speed. You can setup waypoints to your favorite locations, and the compass will show bearing and distance to the waypoint you select. But coupling the GPS feature to DSC is where it really gets interesting.
DSC adds the ability to send and receive digital information on a special channel. With this you get a unique number assigned to your radio called an MMSI for Maritime Mobile Service Id. If you know the MMSI of another radio, you can call it like a cell phone and only it will ring. When you place a DSC call you request a channel that you wish to speak on. When the other radio answers the ring it will automatically switch to that channel. This alleviates the need to pre-arrange the channel manually using channel 9 first.
But wait, that isn't the best part. The other bit of information you can send is your GPS position, and you can send that via an automatic distress call by pressing a distress button located under a little safety door. When you are in trouble, open the door and press the button for three seconds. That's it. It will continually send a digital distress message to all DSC equipped radios with your updated position until one answers and rings your radio back. Your harbor master and the Coast Guard monitor this channel at all times as well as any other DSC equipped radio out there. When you sign up for your MMSI number, you tell the Coast Guard your name, vessel name and type. So they know who you are, where you are, and what your vessel looks like without you needing to speak a single word.
Your DSC radio can ask another DSC radio what its position is. So if you know the MMSI of another vessel, you can poll it for its position, and even set that as a waypoint to get bearing and distance to it as well as an estimated time to intercept, even as it continues to move.
You can also setup a group MMSI. This is a second MMSI that any number of radios can share. With this you can poll for the position of everyone in the group, and see their location as dots on your compass. This is great for regattas or races. The higher end radios can even send this to a chart plotter via a built-in NMEA connector.
A radio with GPS and DSC will set you back about $200. Don't cheap out on something that could save your life. I know you, you will spend $200 on some unobtainium part that might make you go a little faster. But you won't go faster if you are dead. Get the one with GPS.
I hope you see that a VHF radio should be a part of your safety kit and you should never be on the water without one.