PLB vs AIS Beacon – What’s the difference and which one will save you?

As a professional skipper and regular offshore sailor, a question I am often asked by boat owners and new skippers, “which beacon should I get? is AIS or PLB better for me?” Well, let me make a case for BOTH…

PLB vs AIS Beacon – Which One’s Going to Save You

What’s the best beacon or PLB for me? Let me explain how they work and suggest, perhaps you might need both…

You’re bobbing around in the drink. Not planned. Not ideal. So, which emergency beacon’s going to get you spotted, scooped up, and sipping tea in the cockpit again?

That’s where understanding the difference between a PLB and an AIS beacon really matters. They’re both small. They both have buttons you hope never to press. But they do very different things, in very different ways.

What’s a PLB?

A PLB is a Personal Locator Beacon. Think of it as a direct phone call to the international rescue network. When you trigger it, it sends a distress signal via satellite (the COSPAS-SARSAT system or the European Gallileo system), along with your GPS position, to a global emergency coordination centre.

From there, the alert gets relayed to the local coastguard. They’ll launch a full-scale rescue, with helicopters, lifeboats, all the bells and whistles. It works anywhere in the world, land or sea. But, and this is important, it can take a bit of time. The signal’s going via space, then bureaucracy, before anyone launches. If you have one of the newer return link service versions. you’ll get a notification that your signal has been received, either way of a flashing light or a scrolling message on a screen. This is reassuring but if you are bodily in the water, without an immersion suit then time is of the essence. If you’ve just climbed into a liferaft or are clinging to an upturned hull, then you have a little more time. 

What’s an AIS Beacon?

An AIS beacon, on the other hand, is localised. It sends your GPS position straight to any nearby boats (including your own, assuming it’s equipped with DSC and AIS receiver) via Automatic Identification System (AIS)—the same system that shows ships on your plotter if you have one, or on your separate AIS screen like I have on my own boat. 

So when you fall overboard and trigger it, your crewmates get your exact location on their chartplotter or AIS screen within seconds. If another boat’s within 3–5 miles (range varies with antenna height), they’ll see you too. No middlemen, no satellites, just real-time help, right there.

If you’re a solo sailor and plop overboard out of sight of anyone and miles away from the nearest boat with AIS receiver, then you’re whistling in to the wind waving an AIS beacon about. But, let’s say you are sitting in your liferaft,  and you spot a ship not too far away, your AIS beacon can be used to accurately locate you.

If for some reason your AIS system isn’t functioning, perhaps your VHF antenna has been damaged, or you’ve dismasted, a quick way to view and MOB during this time is by way of a a handheld VHF radio equipped with AIS, such as the one I have reviewed from Icom. The Icom 94 AIS unit could be a lifesaver in an emergency., 

So, which is better?

Neither is “better” they’re different tools for different jobs:

	PLB	AIS beacon
	Alerts the coastguard via satellite	Alerts nearby boats via AIS
	Global coverage	Local coverage (~5 miles max)
	Slower response (but big rescue)	Faster local help (if someone’s near)
	Registered to you, works anywhere	Usually integrated into lifejackets
	No satellite gear? Doesn’t matter	No AIS on your boat? No local help

If you sail offshore, you want a PLB. If you’re regularly inshore or coastal, or racing with crew, get an AIS beacon. Ideally? Carry both. One gets your mates to turn the boat around. The other brings the helicopter.

One finds you fast. The other finds you from space.

And remember: none of these work if they’re sculling about at the bottom of your kit bag. Clip them on. Learn how they work. You’re not going to read the manual when you’re armpit deep in cold water watching a mast vanish behind a mountainous wave. 

I have created a buyers guide to Personal Locator Beacons, showing the best beacons on the market right now.

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