Random AIS message

[BigAl.NZ]

I keep randomly getting this false AIS message. Sometimes 1/hr other times don't get it for hours. Its def not to do with speed as I have had it at anchor!

Background: my setup is a Vesper XB8000 and the chart plotter in the picture is a Raymarine Axiom.

I note the message says Position Lost which made me suspicious of the GPS fix on the Vesper, so I went down the rabbit hole of connecting Vesper to my PC and:
(1) Checked connections to antenna (external one) - all ok
(2) Check GPS fix (HDOP is always below 2) - good fix
(3) Watched the GPS window until an error happened (there was no apparent loss of fix) - HDOP was still good.
(4) I also watched the status LED on the Vesper during an AIS message - nothing unusual there.

So I am now getting suspicious of the Raymarine - its GPS antenna is also external and has a HDOP less that 1 with about 1 foot accuracy - so thats not the issue - but I wonder if there is something else triggering the message on the network?

There are no other AIS devices, but there is a second Axiom plotter, Autopilot and radar.

What next steps could I take to find this fault? I think there is a NMEA logging function on the Raymarine Axiom - might try that.

Suggestions?

[NYSail]

Many devised play nice….. when I was upgrading and adding ais, my guy told me to pair Garmin chart plotter with Garmin ais as well as all brands. Little differences may pop up.

Good luck

[dougweibel]

My guess is that your plotter is configured to use the Vesper as the primary position data source. If the Vesper gps has a glitch, or you have an issue with position messages getting lost on your sea talk network, then the plotter will probably switch to using its own gps. However it may generate this error message when it thinks position info is missing and before switching to its internal gps.

[BigAl.NZ]

Was working OK for ages.

[smac999]

to me that is a msg being sent to you by a boat or station... probably to all boats in the area. you can read and send msgs via class a ais. simular to dsc

no internal ais error msg is ever going to say reduce your speed

have you connected using the vesper app (instead of pc) to see if any msgs or errors are listed?

[HeywoodJ]

Originally Posted by smac999

to me that is a msg being sent to you by a boat or station... probably to all boats in the area. you can read and send msgs via class a ais. simular to dsc

no internal ais error msg is ever going to say reduce your speed

have you connected using the vesper app (instead of pc) to see if any msgs or errors are listed?

Exactly! And apparently an old problem in the Huaraki Gulf:

https://jeanneau.proboards.com/threa...-error-warning

Guess, from some online speculation, is that it is related to protection of Bryde's whales in the Gulf. Big brother is sending a message, either to you specifically or broadcast to all users, over the AIS system, to respect a 5 knot speed limit. If the Vesper screen shot was at the same time showing your SOG as 2.5 I'd guess either a system error (if specifically addressed to your MMSI) or a broadcast.

On the XB8000 you can probably get them off the N2K network by turning off PGN 129801 AIS Addressed Safety and PGN 129802 AIS Safety Related Broadcast, but that may also affect things like MOB beacons, so I'd suggest just living with it.

[stevead]

It's not a random message, just an AIS Safety Message, probably sent by a coast station or some other authority.

It's either addressed to you (AIS Message Type 12), or a broadcast message (AIS Message Type 14). Safety Messages do not have any position information associated with them.

If you can log the mmsi address of the sender, look them up on marine traffic and you can find out who it was.

[Marathon1150]

Originally Posted by BigAl.NZ

Was working OK for ages.

We have an XB-8000 connected to a Watchmate 650. It worked well for several years until we left Mexico for French Polynesia. About 2 or 3 days out, the Watchmate showed "no GPS signal" even though we could see the XB-8000 lat/lon output via the Watchmate app on several iOS devices, as well as two iCom radios.

Satellite email to Vesper elicited a response that there wasn't much they could do given our circumstances and that it was probably a problem with the Watchmate 650. Not too many days after that exchange, the Watchmate functioned normally for the rest of the passage. Never have been sure if the signal or connection to the Watchmate was bad, or did the Watchmate suffer from a short-lived, intermittent failure.

Experience with Vesper's support services has always been excellent. I fully understood that there wasn't anything that they could do.

As you may have noticed, Vesper was recently bought by Garmin. My most recent experience (October 2021) with the Vesper helpdesk was not productive. The above mentioned Watchmate, will no longer respond appropriately to key presses. All keys provide the same response and it isn't the most useful. Vesper's help desk responded by saying its an old unit, they don't make it anymore, it probably needs new buttons, and they couldn't help.

Hopefully you will have better luck.

[hjohnson]

Originally Posted by BigAl.NZ

I keep randomly getting this false AIS message. Sometimes 1/hr other times don't get it for hours. Its def not to do with speed as I have had it at anchor!


Suggestions?

I think this is a new feature that was introduced in the most recent firmware for the Vesper units. What you're seeing is a Class A AIS message, sent either by a coast guard coast station, or a commercial ship. Given that it doesn't include a position, it's likely coming from a shore station.

Anyhow, as part of SOLAS conventions, deep sea ships are required to test their AIS messaging system on a periodic basis. If you're in a major port, you can expect to see a test message a couple of times a day.

What would be nice is for the vesper to have a way to filter those out (I don't think it's part of the standard requirements for a Class B receiver), but I don't know if we'll see that. Until then, you basically just have to dismiss them and live with it. There's nothing wrong with your hardware.

[Hartleyg]

This is not being generated by your system, but rather is being received via the AIS system. Someone (probably an "authority" of some sort) is sending this out to tell folks to "REDUCE YOUR SPEED IN A 5K ZONE" - heck, it might even be getting tripped by some sort of speed radar sensor in a channel nearby.


Hartley
S/V Atsa

[HeywoodJ]

Doesn’t need a speed radar - your own AIS tells the “authority” where you are, so they know if you are in the speed restricted zone, and how fast you are going, so they know if you are exceeding the speed restriction (are speed limits STW or SOG?). Easy enough to have their system then send you an addressed (12) or broadcast (14) safety message to slow down. Only outstanding question - when does the type 12 message get followed by a citation in the mail?

[BigAl.NZ]

Originally Posted by Hartleyg

This is not being generated by your system, but rather is being received via the AIS system. Someone (probably an "authority" of some sort) is sending this out to tell folks to "REDUCE YOUR SPEED IN A 5K ZONE" - heck, it might even be getting tripped by some sort of speed radar sensor in a channel nearby.


Hartley
S/V Atsa

Plenty of people are reporting getting this message when doing under 5 knots (including me!) - heck I have had it at anchor.

I believe AIS safety message are broadcast traffic anyway (not unicast). I have also spoke to the Harbour Masters office (I got the MMSI of the Safety Message finally) and its not registered.

Also that message makes no sense since if its broadcast all sorts of people would get it that its not relevant too.

Intereating the Position unavailable refers to the person broadcasting - so I think this message is a prank.

I have reported it to the local authorities and turned of AIS safety messages for now.