As most of you already know, I believe that AIS person overboard beacons are the biggest advance in person overboard (POB) recovery in my lifetime.
In fact, Phyllis’ and my enthusiasm for this technology has led us to change our POB recovery strategy to be 100% reliant on the Ocean Signal MOB1 beacons that we bought in the spring of 2017.
That said, we recently discovered that for much (maybe most) of the first season after we fitted them to the Spinlock lifejacket/harnesses that we wear at pretty much all times when underway, they would not have self-activated.
And, while much of the fault lies with us, our experience does bring to light two potential problems that others relying on the auto-activation features of this beacon, particularly those who bought before mid-2018, need to be aware of.
How Auto-Activation Works
To understand the problems, we need to first look at the mechanics of how the MOB1 activates:
A small plastic piece called the “activation slide” contains a magnet and has a ribbon attached to it that is wrapped around the bladder of the lifejacket, so that when the jacket auto-inflates, the slide is pulled off the MOB1, thereby inducing an activation signal.
To clarify all this we have made a short video. Please watch it before reading on. We have also included rearming, as the process can be a bit intimidating with only the written instructions for reference.
Potential Auto-Activation Failure
So that’s how activation should work, but here’s where it gets scary. In the fall of 2017, when I checked on the beacons installed on Phyllis’ and my Spinlock lifejackets, I found that the slider was hanging loose on both beacons, so that neither would have auto-activated if one of us went overboard.
On finding this, my first reaction was to question why the beacon had not activated after the slider fell off (probably just from normal movement around the boat), and thereby warned us of the problem, both from the strobe light flashing on the beacon, which I would expect to be visible through the fabric of the jacket, and the alarm on the boat going off, not to speak of all the VHF calls we should have received asking if we had a POB.
Now, most of the reason for this problem was our fault. That said, it’s a mistake others could have made, so I’m going to go into some detail.
When we installed our MOB1 beacons back in the spring of 2017, we neglected to install the small plastic clip-on cover with “ARMED” stamped into it (shown in the image at the start of the article and in the video), which prevents the activation slide from being removed gently.
Stupid mistake? Well, yes, but there’s more to know. We bought our beacons from Spinlock and at that time they came with different instructions for installation on their lifejacket than those provided directly by Ocean Signal.
And, in addition, Spinlock had a video on their website showing how to install the MOB1 on their lifejackets that I’m near certain made no mention of the plastic cover.
I say “near certain” because since that time Spinlock have removed said video, both from their site and from YouTube, and simply link to the instructions from Ocean Signal.
But lest you think I made this up to make Phyllis and I look less stupid for making this error, you will note that the product images for the installed MOB1 on the Spinlock site still do not show the plastic cap in place.
That said, there is no question in my mind that Phyllis and I should have followed up with Spinlock and/or Ocean Signal to find out what the plastic cap was for and whether or not we should install it—big mistake and ours alone—particularly since I have now verified that the Ocean Signal instructions packed with our beacons do mention the plastic cap.
Still, when doing this sort of tricky installation, it is always tempting to just watch and follow the video, as we did, and so I fear others could have made the same mistake.
Shipped Without Plastic Cap?
I strongly recommend that all owners of MOB1 beacons, but particularly those who bought early on in the product’s life, or who used the Spinlock installation video, immediately check for the presence of the plastic cap.
And Ocean Signal did tell me that they would mail free plastic caps to anyone who asks for them.
Wait, there’s more. I also discovered when I opened one of our jackets, that the Spinlock-branded activation ribbon had broken at the small added loop made of thick thread.
So even if we had installed the plastic cover, one of our MOB1 beacons would still have failed to auto-activate.
The Ribbon Has Changed, Twice
I called Ocean Signal to share this finding and they sent me two replacement ribbons without the Spinlock branding and with a loop in only one end.
However, I have now found that the latest MOB1 fitting instructions (see image above) show an activation ribbon with no loops at all and a new locking toggle, which would seem to indicate that Ocean Signal and/or Spinlock have decided that the thread loops were a fundamental weakness—I would agree.
I have not checked with Ocean Signal, but I assume (and hope) that they will supply these new ribbons for free to all who request them.
Not a Witch Hunt
Now, at this point, some of you are probably thinking that my purpose in revealing all this is to in some way punish or get back at Spinlock and/or Ocean Signal.
Nothing could be further from the truth. I have a huge admiration for both companies and a deep appreciation for how difficult it is to design and build advanced safety equipment, particularly for a small market like offshore sailing that will never generate big revenue.
Bottom line, there will always be weaknesses in any safety product (particularly first generation ones like the MOB1), and so it’s our job as responsible boat owners to not assume perfection, but rather take the trouble to understand the products we buy to the point that we can identify and manage those inevitable weaknesses.
That said, I am disappointed that despite the fact that I brought both of these weaknesses up in a conversation with an Ocean Signal staff member in June of 2018, that, although they have fixed the problems, they have not, at least as far as I can find, issued any sort of public warning to existing owners. Or enlisted the media to help spread the message as far and as quickly as possible.
In addition, based on this experience, Phyllis and I feel that, even with the improvements to the MOB1 lifejacket installation suggested above, auto-activation is by no means 100% guaranteed.
Therefore, we strongly recommend that all crew members on MOB1-equipped boats should regularly handle and activate the beacon with the goal of firmly fixing in their minds the two methods:
- By rapidly pulling the slider off.
- By pressing and holding the activation button if the slider is not present or if removing it fails to activate the beacon.
Suggestions To Ocean Signal and Spinlock
As I said above, this is a first-generation product for both companies, so expecting them to get it perfect is simply unreasonable. That said, I would make the following suggestions for the MOB1 going forward:
- Both companies should immediately issue press releases to the media detailing these issues and offering free caps and activation ribbons, without loops and with toggles, to anyone who asks for them.
- Both companies should immediately set up an online registration screen on their web sites so that owners can register their products. As it is, neither product even ships with a registration card.
- If improvements are made to the products in the future, an email should be immediately sent to all registered owners.
- All products should be shipped with a card urging owners to register.
Recommendations two and three are trivial to set up using an email service like the one we use here at AAC (Mailchimp). I’m talking seriously-trivial, no more than half-a-day’s work.
Note: Don’t confuse my recommendation above with PLBs and EPIRB’s that are registered with the applicable government authority, because it is they who will receive a signal (via satellite) and verify any activation.
On the other hand, AIS beacons. like the MOB1, are short range devices (max 5 miles) so there would be little point in governmental authorities keeping track of them, and even if they do in some countries (like VHF radios) that would not obviate the need for registration with the manufacturer.
Possible Product Improvements
As I said, the MOB1 is Ocean Signal’s first AIS POB beacon and, I think I’m right in saying, the first in the industry to include automatic activation when installed on an auto-inflating life jacket. Given that, I think they did a great job.
That said, I have two suggestions for Ocean Signal and one for Spinlock, to think about when designing future products:
- Manual activation if slider activation fails should be way easier than on the MOB1, where even finding the red activation button, particularly taking into account the realities of having recently hit the water, probably with cold and maybe gloved hands, could be very difficult.
- Reliable auto-activation should not depend on an add-on plastic cap.
Lifejackets that are intended to have AIS POB beacons installed on them should have a transparent window to allow crew members to easily inspect the status of the beacon without the need to unpack and repack the bladder, a process that is both fiddly and time consuming, and therefore unlikely to get done often enough, particularly at sea.
We are now seeing more beacons coming to market, and some may incorporate my two recommendations above.
Here are some I found as the result of a quick Google search:
That said, I need to make clear that I have not evaluated any of these beacons, and am only including the above links so that others can investigate before making a purchase decision. Also, I’m sure there are a bunch more options and more coming on the market all the time—all to the good.
- Has anyone else found on inspection that their MOB1 beacons were not going to activate properly?
- Does anyone have first-hand experience with alternative auto-AIS POB beacons other than the MOB1? (If you are considering suggesting the Weems and Plath CrewWatcher, or other smart phone-based “beacons”, please read this first.)
We are publishing this article for free as a service to the offshore sailing community. That said, testing, researching and writing about these kinds of issues is very time consuming, and it’s our members (not advertisers) who pay for this work.
- Person Overboard Prevention and Recovery Online Book, including much more in-depth information on AIS POB beacons.