The Offshore Voyaging Reference Site

SeaAngel SA15 AIS Crew Overboard Beacon Compared to The Ocean Signal MOB1

As those of you who have been reading here a while know, Phyllis and I are huge fans of AIS crew overboard (COB) beacons, as well as early adopters—we bought two Ocean Signal MOB1 beacons shortly after they were released.

We are such firm believers in this technology that we have completely changed our COB recovery planning based on the assumption that the person in the water will be transmitting an accurate position over AIS, see Further Reading.

So while I was at the boat show in Annapolis last October I searched out Friedrich Trobolowitsch, CEO of the company that makes the SeaAngel AIS COB Beacon, a competitor to the MOB1.

Friedrich not only plied me with delicious Austrian liqueur-filled chocolates, but also kindly undertook to send me one of his beacons free of charge for evaluation.

Here are my thoughts on the SeaAngel and particularly how it compares to the MOB1.

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Jeff Sowell

This is a great example of why membership is, for my money, the biggest bargain in yachting. You collectively save us all a ton of time and effort trying to research and test these things ourselves. For those of us with Spinlocks, hard to argue against getting the MOB1 given that they have been designed (after some teething pains) to work well together and not “kluged” as you say. That approach may work for less critical items, but not this.

Marc Dacey

I spent some time this afternoon installing two MOB1s in the Deckvests of my wife and myself. Your earlier article on them helped me as I found the instructions a tad opaque…literally as they weren’t printed very well! The little “safety wiindow” went in properly thanks to previous knowledge from you.

I was rather surprised to learn I couldn’t program our MMSI numbers in Canada for a DSC call, but I suspect the default MMSI will serve in the situations we hope never arise. I assume this is also the case with the SeaAngel SA15 units. Pity, as that might be a desirable feature.

Marc Dacey

As a native-born Canadian, I appreciate your commitment to lawful behaviour, John, and am glad to have you aboard. By the way, I may owe you a beer. We head to Canso and 10 further days of self-isolation tomorrow, so you might get it sooner than later.

Sean Collins

As another law-biding Canadian, I would be remiss to recommend using computer with a VPN to connect to another country, where one could easily download the required utility. 😉

Neil McCubbin

According to an email I received from Ocean Signal, the software will enforce the rules applicable to the location of the ISP you are logged to, so getting the software from an enlightened country would not work.
However, since Milvina is in Guatemala,. I will be able to program the MOB1 for maximum safety. Of course I will have to remember to disable that if and when we enter Canadian waters.

Stein Varjord

Hi Neil,
Using a VPN service, (virtual private network), you can move your online location to any country you’d like, no matter where you actually are. VPN also improves safety considerably, as it uses encryption. Lots of providers available, at quite low cost. We use Surfshark, which along with NordVPN is the best known, because they have the biggest marketing budgets. Others are better. Speed and stability are the properties to look for.

Matt Marsh

John, it sounds like the issues with the SeaAngel essentially boil down to:
– It needs better documentation
– It needs better mounting clips

The first issue is easily resolved by finding a couple of technical writers who sail, then giving them a short-duration contract to test the device and write some good clear instructions for it.

The second issue is easily resolved with a CAD console, a 3D printer, and a dozen or so iterations of design – print – test – evaluate – repeat, then send off the best thing you come up with to the plastics shop for production.

There’s a fair bit of thought and discussion involved in both of those, particularly since they’re the kind of problems that are nearly impossible for an engineer who’s deeply involved with the project to identify without outside help. But, once identified, they’re the kind of problems that a manufacturer can solve in weeks, or maybe a couple of months, at very little cost.

Stein Varjord

Hi John,
Thanks for not being too impressed by reading specs and rather connecting it all to reality!
The words “antenna gain” made me think of another potential issue. I’m no specialist in this, either, 🙂 but as I understand it, a higher antenna gain means a more focussed “beam”. The antenna is able to send the same amount of energy further away because it sends more of the energy in one plane, which means it sends less energy in most other planes.

An analogy is a bare light bulb and a flashlight. The bare bulb sends about the same amount of light in all directions, but the light intensity gets low even a short distance away. A flash light can brighten up one spot very far away, but needs to be aimed properly.

Antennas can be just as different as in the analogy, but in this case the difference is definitely much less dramatic, if there even is a difference at all. For now it’s just a guessed possibility.

Anyway, IF the Seangel gets better reach by having a higher gain antenna, it will by default be more sensitive to orientation. It will then send it signal a bit more like a light house and less like an open bulb. A lower gain antenna is also not entirely like a light bulb, but closer to it. Probably not a big difference between these two, but perhaps enough to sabotage the theoretically better reach often enough. At least it might make your point about a proper attachment to make sure the antenna orientation is good even more relevant.

Stein Varjord

Hi John,
Perhaps personal AIS beacons are another reason to develop PFDs a bit, so they get a small inflatable «mast» with a a flashing light and the antenna? Like a small Danbuoy. That way, the antenna should always be vertical and even gets elevated. A webbing loop for hoisting the POB could also be esier to get hold of from a boat if it had a lead line at the «mast» top. A 1 foot/30 cm “mast” might be enough to make a big difference, and would not increase the bulk of the non inflated PFD noticeably. Perhaps this could also be used to hold the spray hood up? I’ve experienced conditions when no hood would mean certain drowning, because of the layer of spray/foam on the water.

Yannick Piart

Thanks for this side by side comparison:)
Your initial article was very helpful to design our MOB strategy (along with a few years spent flying over the ocean in fast pointy nosed grey aircrafts..)
If any of you reading this are interested, I conducted a real life activation of the MOB1 in the middle of the Atlantic and filmed it. I also explain the strategy and mention another piece of equipment that I think is a must have on a life jacket in an “active survival” mindset!
Check it out here :

Geoff Sheridan

That is a fantastic and informative video. Immediately subscribed to your channel.Thanks!
The AIS was showing the MOB as being 200m away, but it was actually still on board, is that right?
Once you have got hold of the casualty, what is your procedure for hauling aboard?

Yannick Piart

Hello Geoff and thanks:)
Yes the AIS was onboard and the 200m makes sense because of the refreshing rate of the position sent by the beacon. To help a conscious MOB we have a ready to deploy floating line.
To be 100% covered we should have a way of hauling out an unconscious MOB but we don’t… Although being on a boat with scoops with access to water level would make it easier. The existing ideas including pulleys and ropes seemed to be too much for the remaining crew onboard to handle on top of everything else. Throw in darkness, stress and nasty weather…
In the end our current idea is : locate MOB, hook and haulout using a winch. Trying to keep legs level to avoid shock in case of hypothermia. But the main idea of all this is to be rescued in a reasonable time, right?

Neil McCubbin

Your idea of hauling a person out of the water with a winch should work on most boats being sailed in open waters today. My 70+ year old wife can winch me up the mast, so could haul a person out of the water.
I do not know why so many writers on recovery techniques show a 4:1 pulley system for this.

Denis Foster

Hello Yannick

Great video and expirement.

Finding the Greatland Green Rescue Flare in Europe seems complicated. On what site did you buy online?

Thank s


Yannick Piart

Hello Denis,

Back then I bought ours on their website
Seems a few other websites are selling them but all US based from what I can tell.
Their literature / customer support is good too!

Charles Starke MD

Hi All
I have a red Greatland Laser and understand there are two problems. One: blue and green are more dangerous for eye sight. Two: Coast Guard helicopters will leave the scene and refuse to help if a laser is shown at them.

So, at present, I don’t know what the safe thing to do is. This is a real problem since the Greatland Laser looks great at first glance.
Will a Coast Guard unit refuse to rescue if alerted by a laser? What color is safe to use?
Best wishes
Charles L Starke MD FACP
s/v Dawnpiper

Charles Starke MD

Addendum: The eye color photoreceptors are much more sensitive to green than blue or red so the assertion that blue and green are more dangerous to the eye in the article above does not make sense.
We have to elucidate the color safety, and the acceptable use with the Coast Guard.


Charles / John,
These lasers are used & known by SAR people (we have had ours for well over a decade – both green & red). Please just read all the good info at Greatland Laser before just asking questions about colors… These are eyesafe lasers and are also EXEMPT from the US federal law for pointing at aircraft in an emergency (& great for near shore pointing at land). Yannick made a great addition to this site with posting his video link. Lots of things taught in SERE should make its way into offshore sailing survival… thanks Yannick. Also, regarding the AIS receiver in his video, that is a great backup that most people dont think about… and the story regarding fishermen without running AIS but still using the MOB1. Thanks again Yannick for pointing this all out to others!

Yannick Piart

Hi Charles,
Here’s my take on it : if I end up as MOB one day, I want every possible chance to be found.
Lasers are annoying (as a former military pilot I have been targeted by some) but it’s not like they make you blind miles away. All they do is flicker on you as from a distance whoever operates it can’t accurately and continuously point the beam to his target. The danger lies more in the distraction they cause for pilots focused on their intermediate/final approach. And yes shining lasers at pilots should be unlawful, just like the article says.
Knowing a few SAR pilots believe me they won’t turn around because you shine your laser at them for a real life threatening situation. You’ll actually make their day and they’ll gladly add a life saved to their career:)

Matt Marsh

Signalling lasers would only be used when you think you can sorta-kinda see or hear the rescue ship or aircraft, but they can’t yet see you.

By the time you’re close enough for the laser to pose a safety risk, the rescue asset is within visual range, so you’d have already put the laser away. An omnidirectional light, eg. a strobe beacon, is much more useful by that point.

There is a world of difference, safety wise, between a 5 milliwatt laser with a current-controlled driver circuit and a 150 milliwatt laser hooked directly to a battery; the $20 stuff off eBay is often the latter.

Murray Fitzgerald

G’day John,
I think the MOB1 is the only unit available in Australia & we have purchased two. I witnessed a test in Pt Philip Bay, Australia, and the range was at least a couple of miles & there is no way the off watch person could sleep through the radio alarm.
Thanks for your work.

Dick Stevenson

Hi Matt,
Agree completely that lasers are best at attracting attention from a long distance and then put away. And can attest that, in practice, the Greatland laser (sends out a long thin very thin red stripe for ease and accuracy of aiming) works as advertised over a couple of miles. We found the red merely eye catching and in no way did we find the light problematic at a distance.
In my casual experience, I would suggest that strobes (like the laser lights) be considered long distance locator beacons for zero’ing in on. Close in I believe them to be very disorienting and, as many are quite intense, hard on vision, and, from memory, SAR folk report that strobes interfere greatly with depth/distance perception from the bridge of a boat or from a helicopter. A constantly lit medium-bright light might be best for the last distance in for a rescue.
My best, Dick Stevenson, s/v Alchemy

Dick Stevenson

Hi John,
Agreed. And especially exciting when clear it has attracted attention to your need for rescue!
SOLAS red parachute flares are amazing. I set up a “flare and fire session” in Portugal with the CG’s help and even in bright daylight they would be hard to miss. In a belt and britches kind of way, the Greatland laser I mentioned is in the Abandon Ship Bag (with extra flares) and the smaller Greatland flares are on our person at night.
My best, Dick

Michael Lambert

Thanks John,
Your mention of mounting one on life rings, got me thinking about how to add one to a Danbuoy, since little kids have neither inflatable pfd’s nor the wherewithal to activate manually. Also guests may not be wearing one anyway.

I hadn’t realized combined buoy/ais units existed; I think I shall invest in one.

Yannick Piart

Yes, KISS. Keep It Simple Stupid is best.
But I see the laser as the equivalent to a flare (multiple flares!) with less things that can go wrong. One instance it could be useful is going overboard with faith in the crew and the AIS but somehow something goes wrong. And now you’re back to “some help” that could be a few hundred meters of you and never spot the rather weak lights that are on the life jackets.
I like the multiple options but as said, to each their own. Isn’t that the beauty of discussing all this?:)

Yannick Piart

(On a fun note, back then I was able to pinpoint the clowns shining my aircraft for fun with their laser using onboard sensors, and pushed the lat long to the authorities. They managed to get them! They were doing this to be naughty. Very different from a rescue at sea situation)


Yes, and a SAR pilot is not going to run away when a laser is flickering… and neither is an airline pilot.

Charles Starke MD

I wrote to Greatland laser and received their cogent reply:

Thank you for contacting us. First of all, Greatland Laser Rescue Lasers are not laser pointers. They send out laser generated light in an expanding fan pattern, dispersing the beam and making them eye safe at distances greater than 13 feet, so for their intended use, they are safe.

The specific bill that you reference is still in committee in the Senate, so I am not sure if it will be modified or passed, but the applicable section in HR 3409 is Sec. 309 Aiming a Laser Pointer at a Vessel, and it references amending Chapter 700 of title 46 section 70014 in the United States Code to make it unlawful to use a laser pointer to strike a vessel in US waters. Item "C" in the bill defines the term laser pointer specifically and our Rescue Laser does not fall under that definition.

As for aiming at aircraft, there is a specific exception made in the current US laws allowing the use of laser signaling devices in case of emergency to signal for rescue.

You are correct that green lasers are considered more dangerous, but the reality is that it is more due to people selling illegal high-powered green laser pointers that it does with the specific wavelength. The green color is a bit more conspicuous and in our testing has a longer range, but there is a tradeoff on battery life due to the extra power required for the diode.

Because our Rescue Laser is not a focused point and the light is diffused, not only is it safe at distance, but it does not "present" itself as a laser strike to a pilot or other possible rescuer. They just see a flash of light. It doesn't "light up" the cabin or anything like that, while illegal higher power lasers may do that. It is very unlikely that a Coast Guard helicopter or vessel would turn back after seeing a flash of light from a Rescue Laser because they would not think they were hit by a laser pointer.

Our Rescue Lasers have been certified by Underwriters Laboratories and have been tested for eye safety by the US Navy and the UK Ministry of Defense. They are used by military units around the world, including by the US Coast Guard and Canada's Coast Guard. We also sell individual units to active duty USCG members that carry them as a personal safety device.

Finally, I have spent years working with the Radio Technical Commission for Maritime Services (RTCM) organization, specifically on a subcommittee concerning electronic signaling devices alongside senior Coast Guard safety officials. I am well aware of the challenges that illegal high power laser pointers cause for both the Coast Guard and aviation in general. I have demonstrated our Rescue Lasers many time to USCG personnel that literally design maritime safety regulations and they agree that our devices are fine and not the types of devices that they are working to control the use of.

I hope that I have been able to answer your questions, but please write back if there is something I've missed. We definitely share your concern about safety and we welcome reasonable regulations that add to the safety of SAR flight crews, as well as commercial and general aviation, and of course, mariners.


Andy Little, President
Greatland Laser


I also called SAR headquarters in Virginia and spoke with several officers. They were not aware of any laser signaling device and thought that their use may be problematical. They expressed that if it wasn’t SOLAS approved it might not be legal. Their awareness may be very different than actual rescue teams, and I do not know any rescue pilots to see what they are are aware of.
The retina is much more sensitive to green light than red or blue. That may be the reason for longer apparent range of the green laser, but the trade off is the higher expense of the green Greatland Laser and the higher power use.
I do rely on my red Greatland Laser and carry it full time in my float coat, both on my own boat, and on various trips for signaling, and to prevent abandonment on the ice on various trips to Antarctica, the Arctic or Svalbard.
Best wishes,
Charles L Starke MD FACP
s/v Dawnpiper


I knew all the above from talking with them a long time ago & some other training, but THANKS for taking the time to contact them & getting a new reply & posting it.

Yes, lots of other good signal uses for these and can be used to reflects off SOLAS tape (dinghy /person down the beach at night etc). Also the green will show up better if the pilots are using NVGs. And there are some IR versions (restricted)… and work where needed.

But back to the MOB1 (& also having/using a Greatland Laser), our plan has always been: 1) stay tied to the boat – John has also made this point many times VERY VERY IMPORTANT 2) when crap happens & for some reason you are not now tied to the boat (or never were: dinghy ride – someone elses boat with no option to clip in etc), hope the MOB1 (or previously a PLB) is working 3) have the laser so you can signal because if you are in the water & the other electronic RF stuff does not work, you being in the water is going to suck & you need to stay calm & at least think you are going to be found & these tiny things are much easier to carry on you then a good parachute flare (we previously carried good mil spec pen flares).

And if anyone is getting the MOB1 for their jackets/harness, please get the Alarm for the boat (John is correct on this one… again).


Denis Foster

Thanks Yannick i willtryyto find a a a te haaips to EUROPE

We have added an. ais mob1 to our Jonbuoy individual MOB life raftt.



Andre Langevin

Hello John,
I had purchased 2 MOB1 to install in our Spinlock vest and i did make test 1 month ago to verify that the ICOM + Furuno Navnet was able to display the target position so that we can GOTO on it. It worked as expected very nice little device ! However you claim having tested the DSC, i guess you have an US version of the MOB1? The ones i purchased at Binnacle are the canadian version and i was not able to program them as US version, only canadian and these don’t seem to support DSC (only AIS) ?

Andre Langevin

In fact i saw it was an IP country restriction so i used a VPN to simulate a connection from USA, but even so i got the application ready to program the MOB1, the MOB1 refused to be programmed. I concluded that DSC has been disabled by the company for Canadian market.

Andre Langevin

Hi John totally with you about the Alarm Box. Unfortunately Binnacle which is my source for Ocean Signal product doesn’t carry it. Can you disclose where you purchased it if its in Canada ?

Chuck Batson

Hello John! Regarding: “…buying one [SeaAngel] to pack in the life raft to help guide SAR assets in for the last five miles, which 406 Mhz EPIRBs don’t do well…” For that I think the McMurdo SmartFind G8 AIS EPIRB would be worth consideration (No affiliation or relationship.)


Bruce Brown

I have been involved with maritime safety equipment and training for over 30 years.
A few comments about AIS COB locator beacons:
1. Inflatable Life Jacket oral inflation tubes were never designed to be the mounting location for various devices. Most often a whistle is attached via an elastic with a string connecting the whistle to the elastic. To continue to mount equipment to the oral inflation tube one might consider the consequence of failure of this piece of the inflatable life jacket.
2. Various signal devices using spring loaded antennas can/have come in contact with the life jacket wearer. Think about the direction of the antenna deployment, the location of the beacon when the life jacket is inflating/inflated and then consider what happens when the antenna uncoils.
3. USCG pilots and co-pilots wear infra red night vision goggles – LED strobe lights do not show up to them. LED running lights, masthead lights, deck lights, spreader lights and personal lights are not visible in the IR night vision goggles. This was relayed to me from a USCG flight crew after we had an opportunity to debrief them about an rescue from a boat i regularly sail aboard.
4. Simple personal light that can be seen with the IR goggles is a chemical snap light.
5. Manufacturers of life jackets are constantly pushed by the consumer to make the devices fit close, pack flat and have smaller profiles. Don’t think that an inflatable PFD was designed to house all the gear you might want to carry. Consider wearing a personal pack with the gear you might need in an emergency on board (fanny pack).

Yannick Piart

Hey Bruce,
I’m just surprised about #3. Are you sure they said IR? I’ve worn some night vision goggles in my previous line of work and they are light amplification device, making that green slightly snowy vision. I don’t recall having any problems seeing any kind of lights with them. But maybe the CG wear something different for SAR?

Bruce Brown

I verified that the goggles they wear are IR goggles.
It came as a surprise – but on further research, i found that LED lighting around airports has been acknowledged as a problem for helicopter pilots using IR night vision goggles. › engineering_briefs › media › eb-98-NVG


Yannick Piart

Interesting, thanks Bruce!

Yannick Piart

Could be. The sensors in optronics can lack a chunck of the visible spectrum or… have a little more! I used to work with a pod that was swing visible + close IR. It would suck (for their own sake and ours) that those USCG choper pilots can’t see LED wavelength:///

Stein Varjord

Hi all,
I’m also certainly no expert, and have no info on the type of night vision gear preferred by who. I also suspect that you all already know all I’ll say, but since some sentences could mean the opposite, I choose to “mansplain”. 😀

I’ve tried both mentioned types of night vision systems, InfraRed and light amplification. They work very differently and enhance different types of objects. The light amplification amplifies the actual light present. I don’t know how it’s done, but the image (on the gear I’ve tried) is rather grainy and “flat”. It’s not easy to find details, but it’s good for getting the bigger picture, situational awareness.

IR is heat radiation. That also gives an image of the bigger picture, since different types of materials and surfaces radiate different amount of heat. To me it seems kinda like a photo negative, so it feels hard to navigate in the image. With practice and better equipment I assume that gets far better.

What I notice as a massive advantage with the IR is that living bodies and most human structures stand out very clearly, like they shine. The image greatly enhances the focus on objects that a rescue pilot would mostly be interested in finding. A LED light also emits heat, but about one tenth of an old type running light and with a tiny surface area. With IR, they are very hard to see unless they are close. They just show up as a tiny dot among loads of other dots that I perceived as noise.

I assume rescue units have access to all kinds of high quality equipment, but I can totally understand if the operatives prefer IR with its great ability to highlight humans very clearly, even in a stressful situation and hostile environment.

Bruce Brown

The night vision goggles used on USCG Aircraft are issued by the USCG. I do not know of any choice that is available to the flight crews other than the issued equipment.
My comments about the LED light visibility is for information as before the debrief – i was unaware of this information.

Bruce Brown

I see lots of boaters with inflatable life jackets and many using the AIS COB locator beacons in various training classes. Few have ever tested their units, fewer have considered the installation (read the guidelines from all manufacturers – COB AIS Locator and PFD). Very few life jacket manufacturers supply information about installing gear on oral inflation tubes. (Spinlock offers the MOB1 so they do include information about installation on their vests,) It is incumbent on owners/users of this gear to insure it will operate as expected. My comments about antenna deployment comes from observations in training exercises with inflatable life jacket deployment.


Hi Bruce,

I have no relation to Greatland Laser but I have been personally involved in real world use of these lasers including rescues & signaling. They work VERY WELL! 

Green (seen with naked eye & NVGs).
Red (seen with naked eye & NVGs).
IR (only seen with NVGs – mostly gov use only).

Get green if you can only carry one.

I have used them all and carry a red & green now everywhere (in a daypack on land & in a vest at sea) & still sometimes IR.

Regarding NVGs, they all see IR light & also amplify most all other light wavelenghts.

The problems with some other lights are with how some LED lights are made, not with NVGs & NOT with these lasers. 

There are thermal image pods with display screens that look for heat/cold and some wont see any light & there are also NVG/thermal binoculars. Maybe whomever you were talking to regarding not seeing lights was using just some thermal when they should have been using all technologies including the naked eye…?

Most issues with NVG use is tunnel vision & that is why there are co-pilots… AND training training training…

Regarding #4: lightsticks either in color or IR versions might be fine for marking a landing zone or clearing a room BUT should not be used as a #1 signal (same size or bigger than a laser & they last way less time). Sometimes it is taught to attach a string to a lightstick & swing above you head but that does not work in the real world for more than 30 seconds on land & is next to impossible in the water.

Regarding #5:
In the video that Yannick did, that is the best current way to light up a jacket. AND since this post is about the MOB1 (I dont care if the antenna hits someone in the face – that person is DEAD if they dont get rescued!) & users should get the stand alone alarm for their boat.

Since we are talking about marine rescue, unless someone is always wearing that fanny pack and has a very good one like the First Spear EE version, it is useless & will be even more under water and the user better have their layout down and make sure it does not hang up while doing all their on deck tasks. And train, train, train.

These lasers work.
The MOB1 on a good jacket works.
Staying tied to the boat (or airframe or vehicle) works best.


David Short

For several of the reasons you have stated, I bought 2 Weatherdock easyONES in 2017. Water activated, spring loaded antenna releases when “pill” dissolves in water, unit is designed to float free tethered with a small line, and float with antenna vertical. Testing time of DSC & AIS reception has had similar times, 30-45 seconds. Looks similar in size to the MOB1.
The original retaining arm for the pill & antenna was easily prone to breakage but they have issued a redesigned component that is beefier. It took me complaining to get it though, the vendor (MRT Sebastian FL) did not go back over sales files to see who had them. They don’t seem to advertise to yachties, concentrate on oil rigs etc.
In 2017 they seemed like the best bet to me. They also say 7 years for the batteries so at that point I will reevaluate. They’re somewhere around $325 I think.

Terence Thatcher

I couldn’t find a better spot for my safety question. Sorry. I have a 20 year old Ocean Signal EPIRB. Regularly send it for replacement batteries and check-up. Should I buy a new one? Are they now better somehow than those made 20 years ago? Thanks.

Chuck Batson

Also, at least one of the newer EPIRBs (notably the McMurdo SmartFind G8) also transmits AIS, which may assist locating you in the last miles, especially if your rescuer is a vessel that’s not usually in the business of search and rescue operations.

Bruce Brown

As a piece of information: USCG SAR helicopters are not equipped with AIS receivers. They do have the homing receivers to home in on the 121.5MHz signal transmitted by all 406 MHz EPIRBs and PLBs however. Don’t expect the USCG helicopters to be using AIS to locate a victim during a SAR event. Know they do have AIS on board USCG vessels and also can home in on the 121.5 MHz transmissions.

John Cobb

I was about to buy an EPIRB but it looks like ACR is going to release some new models that meet those requirements. I’ll wait to see what they look like. ACR has implied in their press release that they will be available by July 1.

Chuck Batson

McMurdo G8 SmartFind EPIRB has already had this for a year or two now — no need to wait.

Charles Hendricks

I came here looking for MOB info because I just knew you would have it covered. Holly and I each have an Ocean Signal MOB1 and their PLB in/on our PFDs

We feel a bit safer knowing we have these devices from a reputable company. The manual for the MOB1 says to do a functional test monthly, a DSC test twice a year, and a AIS/GPS test three times a year.

We have this in our schedule and follow it.

The devices are all two years old.

We recently completed a long offshore passage where we tested the devices before leaving. Then at anchor for a week, we tested them again before setting out to complete our trip.

One of the MOB1 devices was completely dead. Did it die on passage? How long was is dead? This worried us a bit so we reached out to Ocean Signal for help. Over a month later and a couple messages from us, they have not gotten back to us.

The battery tests fine, the unit is just dead.

That brings up another concern. If you only test the DSC, AIS, and GPS only a couple times a year, how can you trust this device that can simply stop working?

I’m now on the hunt for a larger unit that has a user replaceable battery or at least made by a company that responds to customers.

Chuck Batson

Hello Ray, Thank you for sharing your experience. This is indeed alarming (no pun intended). I have two of these units as well. I’m confused by your statement, “The battery tests fine, the unit is just dead.” How are you able to test the battery on a dead unit? Would you please elaborate on this failure mode so I know what to look out for on my units? Thank you! I do hope you get some resolution from Ocean Signal…

Eric Klem

Hi John,

It appears that ACR just released the first combined PLB and AIS unit to the market and I know at least 2 other companies are working on similar units. These seem interesting to me, particularly for inshore singlehanders. Has any of your thinking changed with your new use case?


Stein Varjord

Hi Eric,

Ocean Signal got the main Dame Award for just that last autumn.
The ACR unit looks like it might be just a rebrand version of that one. I’m just on my phone, so I can’t say for sure.

Either way, as far as I can see, the Ocean Signal product is a very interesting update of their MOB1 unit. Not only the extra functionality. It’s also got NFC, meaning it can communicate with a cellphone (very close range) without using power. That way, we can program it and check it’s status, including battery level. Seems like a pretty important feature.

Eric Klem

Hi Stein,

Yes, I have been watching the Ocean Signal PLB3 but as far as I can tell, it doesn’t appear to have FCC certification yet and in their press release in November, they stated that they can’t sell it without that. A quick google doesn’t give me any hits for buying it but maybe it is available in places where the FCC regs don’t apply? It would seem weird to win an award for a product that is not approved but the most up to date thing I can get from their website is: ” This device has not yet been authorized as required by the Rules of the FCC. This device is not, and may not be offered for sale or lease, or sold or leased until such authorization is obtained.” dated 11/13/2022. I would love to hear that they have gotten approval and somehow I missed it.

The 2 devices do appear amazingly similar in appearance as you point out.


John Cobb

I’m interested in their new EPIRB’s. I asked about them via email back in December and they responded by saying they expected the approvals in the first quarter of this year. Perhaps the PLB’s will be approved by then too.