The sun is out, a pleasant breeze sweeps across the pale blue water that seem to be yours alone today and you think you’ve come just about as close to perfect as one can here on earth. Then the boom catches your wife unaware, tossing her unconscious body into what seemed to be, just a fraction of a second ago, such a welcoming and benign patch of water.

Frozen, terrified, feeling as if you’ve been stung by a thousand needles at once, a wave sickness washes through your body. “Do Something!” screams your mind, breaking through a fog of fear that seemed to stretch on forever. You do something. Somehow – how, you yourself aren’t even sure – you get her back on the boat.

She is alive and you get her breathing again, but she is unconscious and is bleeding from her head wound. What now? You’ve done what you can, there is no one nearby to help, so you reach for your only lifeline, the one made of electrons, your radio.

You should have thought it through, made the emergency call sooner but there is no point in second-guessing now. With the call made, your wife is just a few minutes away from being choppered to a hospital by the Coast Guard. She will make it, but just barely.

Let us stop this all too common scenario right here. The line between life and death is perilously thin on the water. Wind, water, boats and people are constantly in motion leaving a collision with tragedy not just a possibility but, over time, a certainty. The only way to protect yourself and your loved ones is to be prepared.

In case you missed it: BE PREPARED

But let’s say that you know your stuff. You’ve taken that lifesaving course, your boat is in good shape and so is its safety gear. What about that radio though? Do you know how to operate it, is it working properly, are the batteries charged, are you sure it’s set to channel 16, does it have enough range to call for help?

If you can’t answer all of these questions in the affirmative without hesitation stay off the water. Stick to the swimming pool or puttering along close – very close – to shore. When things go wrong and you’ve done all you can, you need to be able to reach out for help and that invisible tether of radio waves is often the only way to do it.

For those of you new to the water, there’s a lot to think about here, but don’t be frightened or discouraged. The above scenario was chosen to frighten novice and expert alike into thinking what some would foolishly call unthinkable. Luckily, most people will never have to deal with such an event. But ask yourself “do I want to rely on luck for life and limb?” Of course not.

That’s why this article is going to tell you what you need to keep that tether to safety unbroken. It is a primer on choosing the right kind of marine radio that should be especially beneficial to those new to the water and a useful refresher for those with more experience as well. So here, without further scaremongering, is the nuts and bolts knowledge that every boater needs to know.

The Fantastical Electronical Safety Line

You need a VHF radio. It’s just that simple. It should be the first piece of marine electronics you purchase. Broadly speaking, VHF transceivers come in two form factors – handheld and fixed.

Fixed models operate off of your boat’s battery and transmit and receive via an antenna mounted as high as possible for maximum range. Handheld units are battery powered and resemble “walkie-talkies.” These can also be connected to a fixed antenna to augment their range.

A VHF will usually reach radios at least five miles away and often much further (regularly receiving stations in excess of 25 miles away is common). The range of VHF transmissions is limited by line of sight, which is why a higher antenna location (such as a mast) helps extend the unit’s range.

Fixed unit transmitter power is typically 25 watts (3-6 watts on handheld units) on the high power setting and 1 watt on low power, which is sufficient most of the time. A savvy buyer focuses on the quality of the receiver, which determines how good your reception is and accounts for approximately 75 percent of the unit’s cost.

What to Look for:

All VHF receivers are very sensitive. What makes for a better (and, typically more expensive) unit is greater selectivity. If you operate your boat in the middle of nowhere, a less selective receiver will suffice. If you operate in areas with heavy traffic, greater selectivity is a necessity.

The three specifications that impact performance are adjacent channel selectivity, IM or intermodulation rejection ratio and spurious response rejection ratio. A low-end unit should have a 60 db rating across all of these specifications while a high-performance unit will have 80 db IM and 70 db for the other two specifications.

There are plenty features of lesser importance available in these units as well. Many are able to receive weather channel from the National Oceanic and Atmospheric Administration (NOAA). Some sets have programmable channel memory buttons as well as an assortment of channel scanning features.

These options should be considered secondary to the qualities previously outlined as well as other basic features such as battery life or the ability to use normal disposable batteries in handhelds.

One feature found on new fixed installation VHF radios that is important to pay attention to is Digital Selective Calling or DSC. This mode is one component of the Global Marine Distress Signaling System (GMDSS). DSC comes in two flavors, Category A DSC and Category D DSC.

Both of these send a digitally coded distress call on channel 70, which is reserved wholly for DSC transmissions. Class A units have two receivers, one of which is tuned exclusively to channel 70, so that voice and digital transmissions can be received simultaneously.

With the press of a button,these radios can transmit an automated distress call that includes a unique identifier, known as a MMSI, and even your position if the unit is hooked up to a GPS. The automated nature of DSC should eventually reduce the need to monitor an always-crowded channel 16 for distress calls.

Form and Function

Which form factor is right for you depends on what kind of boat you have and how you use it. If you are strictly a day-boater who doesn’t stray from shore, a handheld model may suffice. A fixed installation is more appropriate for larger boats (meaning most anything north of twenty feet) that can venture further out for longer periods.

Ideally, every boat should have a backup radio. Another handheld unit in smaller boats can be a good hedge against the main unit going overboard (though many new models are waterproof and will float) or having a dead battery. On larger boats an extra radio, if it’s a handheld, is an important addition that allows you to attend to things anywhere on the vessel without losing radio communication.

This can be especially vital in emergency situations where the fixed unit may not be accessible or tasks (such as keeping an eye on a person who’s fallen overboard) require you to be at a different position.

Chit-chat a No-no

The Coast Guard, marine police, towing companies, marinas and other boats all monitor VHF transmissions on channel 16 which is used for distress calls and hailing other operators before changing channels so as not to clutter the distress channel. VHF is a “party line” meaning that anyone can hear all communications on the channel they are tuned to and only one party can talk at the same time. Needless to say radio etiquette is very important. A chat with your buddy on another boat that crowds out a distress call is a little more than a faux pas. Anyone abusing channel 16 may face a serious fine, or worse, if Uncle Sam catches up to them.