EPIRB, PLB, AIS Technology - What's the Difference?

Everyone wants peace of mind when boating offshore on either the ocean or the Great Lakes. By choosing the right emergency communications technologies, you’re able to enjoy boating with the assurance that if an emergency occurs, emergency personnel can be reached. However, it can be difficult to discern which technology is right for you with so many options to choose from.

Our PartsVu Xchange Talks Boating host sat down with Captain Frank Lecardo, the owner and an instructor at the Naples School of Boating, to discuss what boaters need to know about EPIRBs, PLBs, AIS and how to select the right technologies for their needs.

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Could we kick off our discussion by explaining what EPIRBs are?

Frank Lecardo: EPIRB stands for Emergency Position Indicating Radio Beacon. They are used to alert search and rescue services in an emergency. They transmit a 406 MHz distress frequency signal via satellite and earth stations to the nearest rescue coordination center.

The network EPIRBs work on is called Cospas-Sarsat, and it is an international collaboration. It’s up and running 24 hours a day, 365 days per year. In 2021, 263 people have been rescued so far—143 of those people at sea. Worldwide, over 48,000 people have been rescued since 1982.

It is essential for boaters to understand that this network is to be utilized in the case of genuine emergencies, not simply if your boat breaks down and you need a tow.

Can you clarify some of the differences EPIRB and PLB technology?

Frank:​ First, let's talk about PLBs, or Personal Locator Beacons. PLBs work the same way that EPIRBs do— they send a coded message on the same distress frequency and utilize the Cospas-Sarsat network. The most crucial difference is that EPIRBs are registered to a vessel, whereas a PLB is registered to a person. This means that if you switch to a new boat or you decide to use a friend's boat, the PLB will still be registered to you.

EPIRBS, on the other hand, would need to be reregistered if you buy a new boat. If you rent or use someone else's boat, you wouldn't be able to take the EPIRB from your boat. That's because if you did use it, it would send a distress signal describing a vessel that isn't yours. So, you will need to rent an EPIRB, which you can do relatively inexpensively from Boats U.S. Foundation and other sources.

Do you typically recommend manual or automatic deployment EPIRBs?

Frank: Once you decide that an EPIRB is the best emergency communications device for you, the next decision you'll have to make is whether to buy a manual or an automatic deployment unit.

• An automatically deployed EPIRB must be mounted in a place on your boat where if the boat were to sink, it can automatically be released and float free of its bracket. Once it does that, it begins transmitting your distress signal.
• On the other hand, a manual EPIRB means you physically have to pick it up and turn it on to activate the distress signal.

The key to making the right decision is looking at the mounting requirements for the unit and deciding if you have the appropriate place on board the boat to mount it. In my experience, the vast majority of smaller boats (under 40 feet) are better off with a manually activated EPIRB.

In addition to being more expensive, automatically activated EPIRBs have mounting brackets that must be serviced or replaced every two years. So automatic units create another maintenance task in addition to being more expensive to buy.

An automatically deployed unit is often not necessary. If you and your boat are in distress, you usually will have a few moments to grab your EPIRB, turn it on, and grab life jackets.

What are some of the benefits of PLBs?

Frank: PLBs are quite versatile . They can be used not only on the water but also for land adventures, like hiking or back-country skiing.

Additionally, boaters in some areas explore waterways in small boats where it is pretty easy to get lost, cell phone coverage is non-existent, and VHF radio signals can’t be counted on. A PLB is an excellent option for these scenarios.

What are the typical transmission times and battery lives of PLBs versus EPIRBs?

Frank: Once a PLBs is activated, it will transmit for a minimum of 24 hours. It can be stored for six years, which is pretty good battery life.

EPIRBs offer better battery life and longer transmission windows. Typically, about a 10-year battery life with 48 hours of transmission.

How are EPIRBs and PLBs activated?

Frank: By law, PLBs cannot be designed to be automatically activated. Automatic activation on portal units is more likely to be accidentally deployed, inadvertently activating search and rescue teams. These resources and groups around the world are simply too expensive to be misdirected.

On the other hand, some EPIRB units automatically activate when they hit the water. Other EPIRBs are manually activated.

Can AIS technology serve as a replacement for EPIRBs?

Frank:​ No, an AIS (Automatic Identification System) is not a replacement for an EPIRB or PLB. AIS uses a combination of GPS, VHF, radio, and sophisticated digital processing to automatically communicate between vessels without any operator interaction. This technology is somewhat like a digital radar, as it gives precise position information.

AIS technology is designed for vessel-to-vessel communication to avoid collisions. However, only vessels with transponders can be seen. If I’m on the water on my boat and I don't have an AIS transponder, and I'm not sending out an AIS signal, boats that have AIS receivers aren't going to know I'm there. Therefore, this technology isn't a replacement for radar. Radar will spot objects and vessels not equipped with AIS as long as they are above the waterline.

AIS can be a standalone unit or, in many cases with newer devices, included within VHF or GPS chart plotting units. While this technology is extremely valuable, it’s essential to know that AIS technology is not designed for search and rescue communications.