The Offshore Voyaging Reference Site

AIS Crew Overboard Beacons—Setting Up The Boat Alarms Right

When working toward making our boats safer, it’s easy to just buy a piece of gear and then pat ourselves on the back and move on. And I have to confess that’s pretty much what we did in the spring of 2017 when we bought two MOB1 AIS crew overboard (COB) beacons.

But Phyllis and I have learned over years of going offshore, that voyaging safely is a lot more about good installation and developing procedures taking into account the gear’s strengths and weaknesses, then it is about just buying lots of cool safety gear.

So last winter we really thought about how the one of us left on the boat would use an AIS COB beacon to help recover the other in the water, and then documented that in great detail (see Further Reading).

And this spring we dug into how these beacons actually work. In the process we learned some important things, and that’s what this and the next two chapters are about.

Yes, a lot about just one piece of gear, but I make no apology for that since I firmly believe that AIS COB beacons are the most important advance in COB recovery gear of my lifetime.

Let’s start off this chapter by looking at the boat side of the equation, and more specifically what alarms will, or maybe will not, sound in the event of a crew overboard.

And we even have a video at the end to show what a full-on (not test) AIS COB beacon alarm looks like on Morgan’s Cloud.


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Denis Foster

On Panbo website : Lessons learned by causing a false AIS MOB alert
BY BEN ELLISON · AUGUST 8, 2017

This a detailed story of false activation of a Mc Murdo S10 Ais beacon by electromagnetic field and by the way some flaws with NMEA2000 and a Vesper xb8000.

Lessons learned :

Not fool proof device, the battery would of gone dead after a few days of activation.
The Nmea2000 didn allow the Ais alarm and icon to show up.

On our HR46 we both have Vesperxb8000 with Nmea 183 and 2000 so I will check. Our life jackets have Mc Murdo s20 and Oceansignal mob1 so does our MOM ocean safety Jon buoy.

Thanks for this article that reminds us to check installation and its potential week points.
Denis

Dick Stevenson

Hi John,
Once again, I am very admiring of the quality and quantity of work that goes into these reports. You do the offshore cruising (and racing) community a great service.
I am curious about whether you feel that the setting up of the POB system to work effectively had to be such an effort (I hesitate to call it an ordeal, but I suspect that would have been my experience). From my outside observation, you were executing R&D (research and development) which should have been done by the company (ies) involved. I do recognize that there are a number of companies involved (ICOM, Vesper, Ocean Signal, etc.), but it does appear that OS had some obligation to be clear which ancillary units their product plays nicely with, the ones that need tweaking etc. possibly even working with the other companies to develop a (more) seamless package.
My best, Dick Stevenson, s/v Alchemy

Bill Wakefield

John,

Thanks for your continuing efforts for the betterment of all.

We went through a couple of iterations with hardware and device upgrades, and feel comfortable with, and confident of our current MOB alert system set-up. [We still have earlier generation AIS only MOB beacons.]

We test the beacons routinely, but as you point out, that isn’t the same as testing an actual MOB event.

With current generation Vesper AIS units [we replaced our Watchmate 850 with a Vision last year] we are able to test our instruments reaction to an actual MOB alert transmission without having to activate a beacon. [True MOB transmission (over our NMEA networks) from the Vesper, but in a test only mode.]

This is truly useful for confirming things still work as expected– especially after upgrades and tweaks along the way.

Ben Ellison at Panbo just happened to publish an article regarding this feature today:

https://www.panbo.com/vesper-smartais-mob-simulation-a-little-known-nifty-test-tool/#lightbox-gallery-bGlnaHRib3gtMw==/0/

I thank you and Phyllis, once again, for all your efforts.

Cheers! Bill

Marc Dacey

Very good, John. You do the sailing community a real service with these sort of tests. Certainly AIS is in the early days, and I suspect “virtual buoyage” based on AIS will change things even further. But the POB issue is a compelling one. I think AIS tags combined with these sort of alarms (and assuming one has crew that find one charming!) have the potential to superannuate the older PLB tech. I have a ACR ResQFix with 406 GPS broadcast ability that I bought for an offshore delivery in 2009, but it’s the size of a cellphone from 1991 and I wouldn’t mind retiring it. This tech gets us closer.

Devon

Thanks John,
Excellent Article! I have been considering how exactly to set-up our system. We have the Vesper 8000 AIS with both NMEA 0183 & 2000 wired to our system. I didn’t know Ocean Signal had the Alarm Box…..so thanks!!!
I agree: being able to use the AIS as a MOB recovery tool is the biggest safety innovation I have seen as well.
Cheers,
Devon