With the advent of the personal locator beacons (PLBs) and personal AIS units, rescue operations at sea are now much easier to perform. We take a look at the best PLBs and AIS on the market and explain the difference between them

This article was originally published in November 2021, it was price checked and updated on 14 Feb 2023

Not so long ago simply locating a crew member who had fallen overboard in anything other than the most benign of conditions was a massive challenge, but thanks to personal locator beacons (PLBs) and personal AIS units this has fundamentally changed.

Personal Locator Beacons (PLBs) are small devices, typically fitted on a lifejacket, that send a distress message, including GPS position, via satellite to a coastguard operations centre. They work in a similar manner to EPIRBs, but require manual activation and have a shorter operational battery life (usually 24 hours). The beacons location/signal can’t be seen onboard the boat you fell off though. You’ll need an AIS for that. If you accidentally trigger a PLB, you should notify the coastguard straight away to cancel the distress alert.

The personal AIS beacon works using a local radio signal which can be picked up on your chartplotter if it is able to receive AIS signals and on your DSC radio. The typical range for an AIS unit is between 2 to4 miles. These don’t notify the rescue services via satellite, but instead present as a small red circle with a cross target on your chartplotter to help you locate your casualty. If you accidentally trigger an AIS unit, then simply close off the aerial and deactivate the unit and transmit an all ships VHF message cancelling the AIS alert if you are within short range of any other vessels.

In many situations, personal AIS will be a better bet than a personal locator beacon that only transmits a position to a remote location ashore. Some personal AIS units can also be set to activate automatically when a lifejacket inflates. It’s important to understand the fundamental differences between the two types of device.

The best personal locator beacons available right now

N.B. Make sure to check each product is registered for your location before buying.


Ocean Signal PLB3

The Ocean Signal PLB3 won a DAME award at METS trade in Amsterdam 2022.

What’s so special about this PLB?

Well,  it’s the first combined unit that has BOTH 406MHz and AIS radio transmission signals.

Essentially they’ve combined the PLB 1 and the MOB 1 and have this resultant big stick of both.

As you can see, the unit is considerably larger than any of the current personal locator beacons or ais units,  but it’s also no larger than having one of each of the smallest units available from the same manufacturer.

It can be set to auto activate with lifejacket inflation with an arming plate that pops off, and after hands-on testing we can confirm that this does fit into the majority of lifejackets.

Price: £509

Buy from Amazon.co.uk

ACR return link

ACR ResQLink View

Also see our head to head comparison review of the current ReturnLink Service enabled Personal locator Beacons available from ACR and McMurdo

This personal locator beacon, unusually, incorporates a small LCD screen which fundamentally improves the user experience. The return link service pings back a confirmation that your

The PLB425 is supplied with fittings to attach to a lifejacket or to a belt, or around your arm. The estimated battery life is five years.

RRP: £317

Buy from: Global Telesat Communications UK

Buy from: Global Telesat Communications ROW

Buy from: Amazon.com

Buy from: West Marine

ACR ResQLink 400

Alternatively, the ACR ResQLink lower-cost PLB400 without the screen or RLS is available.

RRP: £276 / $299

Buy it now on Amazon

Note: We may earn a commission when you buy through links on our site, at no extra cost to you. This doesn’t affect our editorial independence.

fast find RLS PLB

Fastfind ReturnLink Personal Locator Beacon with RLS

The FastFind is a reassuringly sturdy unit. It feels like a quality bit of kit in the hand, the rubberised sections make it easy to grip. It comes with a wide array of alternative fitment options to fasten this to your life jacket or onto a belt or harness, plus it comes with a neoprene belt pouch.
You can read our head to head comparison review here

Price: £318

Buy from: Global Telesat Communications

Ocean Signal RescueMe personal locator beacon

This compact product is designed for easy single-handed operation. It’s supplied with fittings for attachment of the personal locator beacon to a belt or to a lifejacket.

The estimated battery life is seven years.

RRP: £261/ $329.99

Buy it now on Amazon

Buy it now on eBay

But it now from West Marine

McMurdo FastFind Ranger PLB

The McMurdo FastFind Ranger Personal Locator Beacon (PLB) is a rugged and waterproof GPS-enabled 406 MHz rescue beacon, though it doesn’t float, so make sure it’s tethered on.

The Fast Find Ranger is subscription-free and does not rely on commercial call centres, meaning your request for help is received directly by Search and Rescue authorities. When triggered, the Fast Find Ranger broadcasts a unique registered distress signal that not only tells rescuers where you are, but who you are. This is typically within 5 minutes, but can be up to 45 minutes depending on satellite coverage.

The Fast Find Ranger features a 121.5 MHz secondary homing transmitter which means that once Search and Rescue teams have been deployed, they are able to home in on your exact location. The unit also features a flashing SOS light which can be used to attract attention. The Fast Find Ranger has a minimum 24hr battery life when activated and the battery lasts for 6 years in storage before it needs to be replaced.


Buy McMurdo Fastfind from Global Telesat Communications


The best personal AIS beacons available right now

McMurdo S20 Lifejacket AIS Beacon

As standard this unit has to be activated manually, although if fitted professionally it can be set for automatic activation.

Battery life is again seven years, with 24 hours of continuous operation.

RRP: £175 / $260

Buy it now on Amazon

Ocean Signal RescueMe MOB1 AIS

This compact personal AIS beacon was introduced in 2015 but remains one of my favourites.

It’s a slim device that fits next to the oral inflation tube of a lifejacket. It can be set to activate automatically when the lifejacket inflates, although this is fiddly to set up and needs to be re-done every time the lifejacket is serviced.

An integrated strobe light helps with the final precision locating of the casualty at night.

RRP: £259 / $309.99

Buy it now on Amazon

Buy it now from West Marine

ACR AISLink MOB Personal Beacon

This is another model that has a choice of manual or automatic activation and includes an ultra-bright LED strobe light.

The battery has a seven year lifespan and an operational life of 24 hours. The unit weighs only 92 grammes.

RRP: £260

Buy it now on Amazon


This compact model has to be activated manually, rather than being automatically triggered when a lifejacket is inflated.

However, its size and shape mean it can be easily carried by crewmembers even if they are not wearing a lifejacket.

Price: £218

Buy it now on Amazon

What’s the difference between a personal locator beacon and a personal AIS unit?

Personal AIS transmits locally and enables the casualty’s position to be displayed on the chartplotter of your own boat and others nearby, including lifeboats once near the scene.

By contrast, personal locator beacons transmit their primary 406MHz signal only to a remote rescue coordination centre. This can be helpful in raising the alarm and in deploying search and rescue assets, but doesn’t help your own boat and others around you to locate a person in the water.

Personal locator beacons transmit a secondary signal on 121.5MHz, which is helpful for lifeboats homing in on a casualty, but other vessels are rarely equipped to receive this signal. In addition, although the units are generally buoyant, all PLBs need the antennal to be held in the air manually and the body of the unit must be supported out of the water for the GPS antenna to work.

For some time there has been talk of combining both types of Personal locator beacon and AIS into a single product. We know that development of this has been in progress for some time, but getting a new product through the rigorous testing and licensing takes an inordinate amount of time and expense for the manufacturer. ACR are currently developing something but we have yet to see it.

What’s the best option? Ideally both a personal locator beacon and personal AIS for each crew member – that’s what I have when racing offshore or undertaking long passages when cruising. Don’t underestimate the massive step forward this represents – having both devices all but eliminates the search element of a search and rescue mission. Their adoption therefore ought to become widespread.

If forced to choose only one type, providing my boat was equipped with an AIS receiver, I’d likely plump for the personal AIS, particularly if sailing with other people on board and in an area in which there are generally other boats around.