If you head offshore or participate in competitive sailing then you'll need to consider a PLB and/or an AIS beacon. Tech Editor and marine safety gear and comms specialist, Fox Morgan has tested an array of the current beacons on the market to help you decide what's the best one for you.

The best personal locator beacons on the market – hands on testing

Locating a crew member who’s fallen overboard in anything other than the most benign of conditions is a huge and frankly scary challenge for those onboard.

Your odds, as a person overboard being recovered are less than 50:50 according to the latest MAIB report stats. Add a lifejacket and your odds of being found are still marginally 50:50 but you at least might survive long enough to be rescued. That’s if your lifejacket has a sprayhood, light and reflectors. If you’ve been thrown a danbuoy or johnbuoy MOB marker then you have a slightly higher chance of being seen. But when you’re alone in mountainous seas feeling very small and insignificant, there’s a couple of pieces of tech that will up your odds of being found to over 90%. 

This is where a personal locator beacon can be a genuine life saver.

There’s an array of beacons on the market for a variety of activities and circumstances. I have picked out the  best on the market, across all sectors. From VHF enabled AIS beacons, to satellite radio poisitioning beacons and then to satellite trackers that have an SOS function

Jump to PLB
Jump to satellite trackers

At a glance: The best AIS beacon, The best combined beacon, Best PLB, Best satellite tracker



The best personal AIS beacons available right now

sMRT alert AIS beacon

Reasons to buy: A flat slim robust unit, powerful signal, simple to use, DSC automatic calling, NFC enabled

Reasons to avoid: This is not a satellite beacon and works only with localised rescue operations

Specifications: Battery Life  Minimum of 12 hours at -20°C, Battery Shelf Life at 20°C 5 years, Dimensions 137mm (H) x 62mm (W) x 26mm (D), Weight 212g, waterproofing: IP67, Alerting Radius Up to 5NM (depending on height of antenna)*

I was very pleased to be one of the first British media types to get my hands on this beacon, new to the market for Summer 2024. It is the first out of the blocks, so to speak to be class M compliant and meets new AIS transmitting standards.

It is a chunky item, and whilst it can be mounted inside a lifejacket, I have used this attached to my lifejacket belt or in a pocket. It doesn’t need the lifejacket to inflate to activate, simply fully immerse it for 2 seconds in water or press the big button.

There’s a really simple slide down switch behind a flap on the side to activate. If you’re in the water it will go off automatically and start transmitting your location to all local AIS receivers. It will also send a DSC alert to all VHF radios.

Using NFC on your smart phone there’s a sMRT beacon management app for ongoing devices checks and monitoring. The sMRT ALERT internal DSC receiver allows a confirmation when its DSC distress signal has been acknowledged.

It’s probably one of the most power AIS beacons on the market right now. I’m glad I have one in my kit bag.



McMurdo S20 Lifejacket AIS Beacon

Reasons to buy: A flat slim unit fits easily in most lifejackets, easy manual activation, designed to fit inside a lifejacket outer casing

Reasons to avoid: If you are sailing solo then this will not notify anyone by satellite and may not be much use if sailing far from many other people/boats.

Specifications: battery life when activated 36 hours. Battery service life: 5 years. dimensions 129x52x40mm (L*W*D), Weight 160 g, Waterproof IP68, operating frequency : VHF Frequency AIS 1, 161.975MHz,  AIS 2, 162.025 MHz, VHF Range 4nm typical with receiver antenna / > 5m above sea level

I have had this unit fitted to most of my lifejackets in the past. It is simple and easy to operate. A swift pull of the lanyard and the housing slides off and the beacon is working, giving a clear signal to boats nearby of the MOB icon on all AIS screens.
As standard this unit has to be activated manually, although if fitted professionally it can be set for automatic activation by way of a lanyard that pulls of the activation tab when the lifejacket bladder inflates. It’s quite a basically system but it usually works pretty well.

The casing can take quite a sharp pull to remove it from the body of the unit so it is worth practicing this if you have the opportunity to familiarise yourself with the force required.

The main thing to note is that under the red removable case is a secon slide out piece of plastic with a magnet. This must be all the way out to activate the unit and the aerial must be pointing as high and skyward as possible for the best signal.


Ocean Signal RescueMe MOB1 AIS

Reasons to buy: very slim design fits almost every lifejacket,

Reasons to avoid: If you are sailing solo then this will not notify anyone by satellite and may not be much use if sailing far from many other people/boats.

Specifications: operating  Frequency 161.975/162.025MHz, Waterproof 10m depth, Weight 92 grams, Dimensions 34 x 38 x 27 mm / 5.3 x 1.5 x 1.1 inches

This compact personal AIS beacon was introduced in 2015 but remains very popular.

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.

This is the smallest lightest AIS unit currently on the market that I know of at the time of writing.


ACR AISLink MOB Personal Beacon

Reasons to buy: ACR is a tried and trusted name in the marine safety gear market, Simple activation, can be autoactivated

Reasons to avoid: If you are sailing solo then this will not notify anyone by satellite and may not be much use if sailing far from many other people/boats.

Specifications: Manual or Automatic Activation, Battery Life 7 Years from date of manufacture or after emergency use, 24+ hours operational battery life, Waterproof 10 Meters, Weight 0.2 lbs (92 g), Dimensions 4.52 x 1.81 x 1.06 in. (115 x 46 x 27 mm), LED Strobe Light, operating Frequency AIS channel 1- 161.975 MHz, AIS channel 2 – 162.025 MHz, DSC 156.525 MHz

ACR are to emergency maritime equipment was Hoover was to Vacuum cleaners. In the USA people don’t refer to personal locator beacons and AIS, they simply refer to them as ACRs.

This model from ACR is an AIS unit only.

When activating the unit the central grey panel is pulled away which reveals a sprung antenna that unfurls rapidly to stand at 90 degrees to the unit. Beware of your eyes when inspecting how this part works.

The unit comes with a range of lifejacket methods for fixing.



Weatherdock Easy 2-MOB

Reasons to buy: works with a small group of vessels as a loop using bluetooth, works as a regular ais device for all ships, built in buoyancy

Reasons to avoid: risk of accidental trigger if sailing in extreme conditions, uses a salt capsule for autoactivation, this is not a satellite positioning beacon

Specifications: Displays: 9 LEDs – 1 x Program LED, 2 x Status LED, 6 x Flashing Light LED, Frequencies: AIS 161,975 and 162,025 MHz, DSC: 156,525 MHz., Dimensions (L x W x H): 195 x 50 x 30mm, Weight: 120g. red LED torch. Fully automatic activation on contact with water. 12+ hour battery life. DSC distress call up to 8 different ships in the ‘closed loop’ process. DSC distress call in the ‘open loop’ procedure automatically after 10 minutes.  Self buoyant

The easy2-MOB automatically activates upon contact with water and immediately begins to send emergency signals to a group of up to 8 vessels, including the mother ship in a closed loop.
These MMSI numbers can be programmed via a Bluetooth connection from a smartphone with the free Weatherdock app.

To fit the AIS MOB, simply open the life jacket outer casing enough to allow a space to slide the unit into.Push the unit upside down between the folded bladder. The safety line is attached inside to a secure point within or on the lifejacket.

To activate the automatic activation, the yellow slider has to be moved from ‘disarmed’ into the ‘armed’ position at the left side.

Buy it now from Force 4



Reasons to buy: Small compact unit, manual operation is very simple, fits easily in a lifejacket

Reasons to avoid: the manufacturer is not very well known in this area of tech, not a satellite positioning beacon

Specifications: Dimension 115 x 40 x 22mm, weight 95g. 7 year battery built in which will operate for at least 24 hours continuously when activated. waterproof.

Digital Yacht teamed up with SIMY to create this particular AIS MOB Beacon. Never heard of SIMY? No, me neither until I saw this. SIMY is a division of leading space company Syrlinks (designers of the Rosetta probe) who specialise in miniaturising and low power electronics.

The AIS MOB100 Beacon incorporates 72 channel GPS and AIS SART transmitter.

When activated the red cover is slid off downwards revealing a coiled antenna that slightly resembles a slinky spring. After acquiring a GPS signal, it sends the current location as an AIS transmission which can be detected by any vessel equipped with an AIS receiver.

Range stated by the manufacturer is 5-10nm, but in reality you’ll be lucky to get 4nm range from any AIS unit when it is floated at water level amongst 1m waves.

If activated accidentally, the MOB100 can be physically reassembled and reset.

The new MOB100 measures just 115 x 40 x 22mm and weights just 95g. It’s designed for manual activation or can be attached to an automatic inflation lifejacket onto either a strap or the lifejacket inflator which will allow it to automatically activate when the life-vest inflates. The unique cover design requires just a 1cm downward movement created by the strap and lifejacket inflation to auto activate and deploy the spring antenna. On foam filled life-vests, the unit would be fitted to the outside and set up for manual activation.



Best Personal Locator Beacons (Satellite radio beacons)


The best combined AIS and PLB

Ocean Signal PLB3

Specifications: 406hz satellite radio beacon | AIS radio beacon | return link service | near field communication to battery check and device status | Size 20 x 3.6 x 3cm | Weight 190g | Operational Life 24hrs at -20ºC

Reasons to Buy: A single device that covers both AIS and satellite location beacons, only one battery to replace when the time comes for replacement, can be semi-automatically activated by a lifejacket inflation

Reasons to Avoid: At the top end of the price range for PLBs, quite large and may be a struggle to fit inside some lifejackets

There’s currently only one beacon offering a combined AIS and PLB function n one unit and thats this formidable beacon from

It is the first beacon to combine both PLB and AIS units in one. It is something people have been asking for since small wearable beacons were created.
Now a little reality check, the beacon is not small. Yes it fits in the hand and by SHIPS epirb standards it’s small, but it’s essentially the MOB1 and the PLB1 combined if you stacked one atop the other. It creates a longish stick style of beacon.

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 offshore lifejackets.

But buyer beware, this is quite noticeable within a 170n lifejacket. You will feel it stiffens up one side of a lifejacket considerably. It’s also a bit big/long to fit into a pocket.

The auto-arming procedure is quite fiddly. If you are at all unsure, then I highly recommend taking this to a reputable lifejacket service centre or ocean signal office and getting the experts to show you how it’s armed when fitted to the bladder of your lifejacket. If you have to frequently inflate your lifejackets for safety protocols and inflation testing then it might be a bit of a faff. I have one fitted to my own Spinlock Deckvest 6D (it’s a squeeze) but I’ve familiarised myself with the unit and plan to manually activate it should I need to.

Read our review of the PLB3 here


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

Specifications: 406hz satellite radio signal | return link service | 28hr battery life when activated | strobe light | weight 148g | 11.48 cm (L) x 5.16 cm (W) x 3.78 cm (D)

Reasons to Buy: A smooth easy to operate PLB, return link service, comes with an array of methods of attachment to a lifejacket

Reasons to Avoid: the casing feels like it might be less robust compared to other ruggesdised competitors

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 ACR reQLink View works in the same was as the ACR 400 unit with the aerial mounted in circumpherence around the body of the unit. SLide the end of the antenna out of the little slot on the side and then rotate it manually around using the hinged based. This reveals the activation button.

With the unit being mounted inside a lifejacket for example, it is possible for the aerial to be pushed loose of its holder and given the style of the aerial wrap around, stowing this in a pouch can be fiddly to extract in an emergency. The clear housing does make it easy to inspect though to check for any water ingress.


ACR ResQLink 400

Specifications:  dimensions 11.48 X 5.16 X 3.78cm, Weight 144g, Battery Replacement: After 5 years or emergency use, whichever is first., battery life in use: 24+ hours. Waterproof: 5 Metres @ 1 hour | 10m @ 10 minutes..

Reasons to buy: buoyant, good value, easy to use

Reasons to avoid: difficult to use this with a pouch as the aerial is wrapped around the outside, will not alert nearby vessels using AIS

The ACR ResQLink 400 is a simple unit with fewer bells or whistles than the return link model we have featured. It still activates an emergency response by satellite signal when activated. The aerial wraps around the unit externally on this so deployment is simple. Slide out the aerial tab from the slot on the side and then rotate it on the built in hinge. This exposes the activation button which is at all other times protected behind a piece of trim attached tothe aerial.

I like this simple way of opening up the aerial, but the downside s that it does make keeping the unit in a neoprene pocket or protective case a bit of a faff if you need to deploy it. The clear casing allows the user to see inside at the electrical gubbins inside. You’ll also be able to see if there’s any accidental water ingress too. So it’s very easy to inspect when periodically testing it.


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.

McMurdo Fastfind ReturnLink Personal Locator Beacon with RLS

Specifications: dimensions 36 x 50 x 112 mm (1.42 x 1.97 x 4.41 in) | Weight 164g (5.9 oz) | return link service | transmit duration > 24 hours @ -20 °C

Reasons to Buy: reassuringly ruggesdised outer casing, Return link service, easily fits into a pocket or lifejacket, has lots of methods for attachment included in the box, plus a spare top cap.

Reasons to Avoid: some may not like the fusible top cap that is a single use plastic item, it doesn’t have any built in floatation. It isn’t an AIS unit so nearby, non SAR vessels won’t see the signal from this.

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. Activating it is quite simple, pull up a small lever and pull hard. This breaks a tab inside and allows the top cap to be removed. The aerial unwinds to stand vertically at 90 degrees to the unit. The beacon is activated by pushing the on button.

This is one of the best PLB’s on the market in terms of PLB function. just remember, this does not have built in AIS so if you want nearby vessels to be able to find you, then you will need an AIS beacon too.
You can read our head to head comparison review here

Buy from: Global Telesat Communications


Ocean Signal RescueMe personal locator beacon

Specifications: battery life when activated 24 hours. Battery service life: 7 years. dimensions 7.7cm x 5.1cm x 3.25cm, Weight 116g

Reasons to buy: tiny beacon fits in a pocket, on a belt or inside the lifejacket casing. easy to operate singlehanded.

Reasons to avoid: some may find it too small to handle with cold hands. Doesn’t give a location signal to the vessels in the nearest vicinity, (you’ll need an AIS unit for that)

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

The outer casing is smooth to touch with a neat design to stow the aerial. Unlike others, this aerial needs to be pulled out manually and rewound back in using the little finger winder on top.

You won’t accidentally have your eye out with this one as the aerial springs to attention as you’ll be manually operating it, however this does mean that you could forget this part when you go for the trigger button in a bit of an emergency and your brain  malfunctions.
This beacon has un-doubtably saved the lives of quite a few people as documented in some of the mainstream press articles. Including one of our own from a stort in our sister title Yachting Monthly, when a “PLB saved my life

You can see just how small this device is in the hand of the fellow whose life it saved.


McMurdo FastFind 220 PLB

Specifications: Size W x D x H 112 x 36 x 50mm, 6 year replaceable battery life, Minimum of 24 hours continuous operation, Waterproof to 10m, signal frequency: 406 MHz international distress signal and 121.5 MHz homing signal, SOS LED flash light

Reasons to buy: Good value for money, simple robust design, comes with good range of attachments in the box.

Reasons to Avoid: does not have inherent buoyancy, does not inform local vessels using AIS of your location – you will need a different beacon for this function.

The McMurdo FastFind 220 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 or wearing a float jacket..

The Fast Find 220 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 220 has a minimum 24hr battery life when activated and the battery lasts for 6 years in storage before it needs to be replaced.


Kannad SafeLink SOLO

Specifications: Size W x D x H 112 x 36 x 50mm, 6 year replaceable battery life, Minimum of 24 hours continuous operation, Waterproof to 10m, signal frequency: 406 MHz international distress signal and 121.5 MHz homing signal, SOS LED flash light

Reasons to buy: Good value for money, simple robust design, comes with good range of attachments in the box.

Reasons to Avoid: does not have inherent buoyancy, does not inform local vessels using AIS of your location – you will need a different beacon for this function.

The SafeLink SOLO PLB is good value for money.
Waterproof to 10 metres it is easily activated by snapping off the topcap and pressing the activation button concealed under the cap facia.

It comes in the box with a lanyard, a buoyancy pouch and a universal carry pouch; which can be attached to a belt or strap.

The SafeLink SOLO is a 406MHz beacon which operates on the global COSPAS SARSAT satellite communication system, supported by international government search and rescue authorities around the world

It also transmits on the 121.5MHz homing frequency so that when the emergency services are nearby they can ‘home in’ on the signal. This is not an AIS signal though so only vessels equipped with the receivers to home in on 121.5 can do so. If you want local vessels to be able to find you, then an AIS beacon is also required.

It also has an SOS LED flashing light that is manually activated to be seen/identified visually in the dark


The Best Satellite trackers / personal beacons


best satellite messenger - garmin inreach mini 2

Garmin InReach Mini 2

Specification Dimensions: 5.17 x 9.9 x 2.61 cm, Weight: 100g, Waterproofing: IPX7, SOS button, Voice calls: No,  2 way messaging: Yes

Reasons to buy tiny device fits into any compact gear set up, easy navigational experience via the app

Reasons to avoid some may find the interface fiddly, might be a bit small for some to handle

The smallest tracker currently available on the market the Garmin Inreach Mini 2 is a wearable device. Clip this to a bag or belt loop and you’ll virtually forget it’s there.

It can store 100 waypoints or favourite locations and has a battery life of up to 90 days, but this will be much less if you set the tracker to a short interval of say 10 minutes.

You can hook up to it via the Garmin App and send and receive texts using bluetooth connectivity with a smart phone. If your phone battery dies, you can still send pre-set messages directly from the unit.

A typical subscription cost for an average frequent user would be:

“Recreation Plan”
Activation Fee: £25.00
Monthly Fee:  £32.00*
Minimum Term 30 Days
Suitable For  Frequent users sending regular messages/track points
Inclusive Allowance  Unlimited SOS, Up to 60 Text Messages or 600 Tracking Points
Overage Charges : £5.80 per 1,000 Bytes Used, Text Message: £0.50 +/- , Track Point: £0.05



Buy from Global Telesat Communications

best satellite messenger - zoleo


Specification Dimensions: 9.1 x 6.6 x 2.7 cm, Weight: 150grams, Waterproof: IP68, SOS button: monitored 24 hrs, Voice calls: No, 2 way messaging: Yes (via a smart phone and app)

Reasons to buy handy built in clip, rugged outer, simple interface, useful accessories for multiple ways to mount the device

Reasons to avoid needs a smart phone and app to send messages, doesn’t support voice calls

A smart little satellite messenger, the Zoleo relies on your mobile phone to function fully using an app.
With the app you can message others with the same app on their phone. The Zoleo will use your phone signal if it has one first rather than use your satellite credit/allowance, only using it when your mobile phone is out of range of any land signal.

I like the fact the Zoleo gives you an assigned number that doesn’t change for receiving SMS texts and there’s a dedicated email address too which the Zoleo can check periodically for you.

As with all of these satellite messengers, this one has an SOS button which Zoleo the company have specified as being monitored 24 hours.
You can control how often ZOLEO checks the Iridium satellite network for new messages. Choose a shorter interval for a better messaging experience or a longer interval to extend battery life of the device.
Without a mobile phone you can still press the check in button (the tick button seen in the picture above) which notifies a designated person of your GPS coordinates and you can of course use the SOS button if there’s a genuine emergency with imminent threat to life.

Typical costs for subscription

Monthly Fee for a mid range user £32
Satellite Messages Included: 250
Additional Messages £0.55/ea
Satellite Check-in Messages: unlimited
Mobile Network & Wi-Fi Messages: unlimited

Location Share+ is an additional £4.50 per month


Buy Zoleo from Amazon


best satellite messenger - Bivy

ACR Bivy Stick

Specification Dimensions: 11.35 cm x 4.7 cm x 2.11 cm, Weight: 100grams, Waterproofing: IP67, SOS button: 24/7 monitoring provided by Global Rescue, Voice calls: No, 2 way messaging: Yes (via a smart phone and app)

Reasons to buy easy app interface, roll over credits, you keep the same number

Reasons to avoid not ruggedized, no built in screen,

The Bivy Stick and Bivy App from ACR transforms your smartphone into a fully-functioning piece of satellite communication equipment.

There are no activation fees; simply connect your phone to the Bivy Stick via Bluetooth to access the Iridium satellite network.

Features including two-way SMS messaging, SOS calls, location sharing, one-touch Check-in, and in-depth weather reports sent to your smartphone.

On activation you are assigned a dedicated phone number and email allowing you to maintain the same contact details throughout, unlike some other systems that assign a new number with each message making it impossible for outsiders to initiate contact. In the past I have used a sat device that gives me a random number which can be confusing when contacting friends and family initially. The bivy stick does away with that.

The Bivy App gives stats including current pace, mileage, altitude, as well as offline maps.

Typical mid range user contract might look like

PLUS plan based annually (monthly plans are also available)

Cost Per month £24.99
80 Credits
Overage Charge Per Credit: £0.50/Credit
Dedicated Phone Number & Email
Includes Tri-Network Coverage
Satellite, Cell, or Wifi
Unlimited Check-In Messages
Customisable preset messages with GPS coordinates


Buy now from Global Telesat Communications

How to choose the right personal locator beacon for you and your boating activity

You have two choices: an AIS type beacon which when activated shows up as a circle with a cross on any AIS radar screen of nearby vessels (upto 5 mile range) and allows any vessel that can see this signal to home in on it locally. Some handheld AIS radio devices can also help target a MOB signal too. – Icom M94DE VHF Marine Radio
You could use a personal AIS beacon from a liferaft to assist in local SAR efforts where small craft are trying to locate you as part of a coordinated effort. This is how Kirsten Neufshafer found Tapio in his liferaft when his boat sank rapidly in the Golden Globe race 2022. Accidentally triggering an AIS beacon can be cancelled by simply switching off the unit and an all stations call by VHF to nearby vessels who may have seen the MOB signal appear.

There’s also the PLB which communicates with overhead satellites in the same was as a ships EPIRB (electronic position indicating radio beacon) and works on a  frequency picked up by satellites alerting search and rescue teams ashore. ( via a network of control centres). This type of device does NOT give a localised AIS signal that a small vessel could pick up.  The battery life is a little less than a ships EPIRB but essentially it does the same thing, just in a very small device. You might use a PLB of this type to signal a mayday situation, such as from a grab bag or life raft and you might not necessarily be a person overboard to use this, but it should only be used in case of grave and imminent danger to life. Accidental triggering of one of these requires a call to the coastguard to cancel the distress signal officially.

If you are looking for other safety gear then we have several buyers guides you may find useful

Marine safety gear, all the essentials you’ll need for safe sailing

Best EPIRB: 5 emergency beacons for leisure sailors

Best lifejacket (170 to 275N)

Best liferaft (6 tested)

Pip Hare reveals the 15 essential items she packs in her grab bag