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Old 08-02-2018, 16:31   #1
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Weirdest AIS seen!

We're back in Nassau and once again we are seeing weird AIS transmissions.
Why not a thread to document some of these transmissions.
Have look at MMSI 377636000 in this VDR recording! Their heading keeps doing continuous 360's, with a steady course!!??

weird.txt.pdf

Thomas
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Old 08-02-2018, 16:46   #2
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Re: Weirdest AIS seen!

Perseverance II 38 m pleasure craft, St Vincent & Grenadines reg. Spends a lot of time going back and forth between Miami, Nassau, and Freeport.
Probably mounted the unit in the rotating restaurant?

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Old 08-02-2018, 17:17   #3
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Re: Weirdest AIS seen!

What an ugly boat.
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Old 09-02-2018, 02:51   #4
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Re: Weirdest AIS seen!

AIS antenna mounted on top of the radar antenna???
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Old 10-02-2018, 10:51   #5
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Re: Weirdest AIS seen!

Not bad.....doing 7.7 kts while aground!
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Old 10-02-2018, 11:10   #6
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Re: Weirdest AIS seen!

^I remember ogling one of the earliest GPS units on a friend’s boat. The numbers would drift around, indicating that we were zooming from one side of the bay to the other, (while firmly tied to the dock.)
“Hold on, here we go again!”
*Crew practices Star Trek maneuvering poses*
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Old 10-02-2018, 12:39   #7
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Re: Weirdest AIS seen!

It's probably not the fault of the AIS transponder. The position/SOG/COG comes from it's GPS and you are seeing a steady course. But the heading data comes from an external sensor. On smaller boats it's often from the A/P but on this boat it might be separate. Maybe the heading sensor is mounted to close to large metal or more likely is malfunctioning. If it's only being used by the AIS then the boat may not even be aware. The manifestation will be the boat's icon rotating around or pointing the opposite direction from the course.
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Old 10-02-2018, 13:16   #8
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Re: Weirdest AIS seen!

And nobody tells them. As you can't discover this by yourself but viewing Vesselfinder or Marinetraffic. Or your boat on a different plotter.
It might be advisable to give a short notice to the vessel.

Sometime ago we had here in the Barcelona harbor two vessels with the same MMSI thus littering the OpenCPN MMSI file. Visually the boat(s) was jumping and as the static message was different, the two vessel names were shown.
Got the yard manager on the phone and then the installer of the AIS and they fixed it. They were using the same test MMSI on the two installs while in the yard....
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Old 13-02-2018, 05:59   #9
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Re: Weirdest AIS seen!

OK! Try this on for size! These SART alerts are the most annoying things that will appear on your OpenCPN screen. Here in Thailand, they are a daily event and it's not unusual to see 2 or 3 of them active at any one time.

I have confirmed "sightings" of 3 of these annoying alerts. Two were very small, local Thai longtail fishing boats. One doing about 10 knots! The other was anchored and I waved when we went by, all was well. The third was in open open water, 1/2 mile away and it was doing 20kts!! The only thing I saw in that location was a jet ski flying across the water with 2 people on board. These types of SART sometimes transmit for days!

To minimize the annoyance, I've resorted to dragging the alert box as far as possible off the screen so I don't have to see them anymore. I was anchor the other day and the one in the screen capture popped up. This one is special!!! I'd love to see the radio transmitter that sent this one!! Sadly, it was too far away for me to lend assistance!
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Old 13-02-2018, 07:32   #10
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Re: Weirdest AIS seen!

https://opencpn.org/wiki/dokuwiki/do...led_or_ignored
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Old 13-02-2018, 14:20   #11
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Re: Weirdest AIS seen!

That's someone with an activated AIS-SART (not AIS-MOB). Not a proper use of course. We've seen cases where people use AIS-SARTS to locate fishing nets so perhaps that's what's going on here.

And the manufacturer number #85 isn't in the list of registered manufacturers so who knows what the device is.

A good example of AIS being misused and creating a nuisance (at best) for others.

AIS-SART Manufacturer IDs
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Old 13-02-2018, 14:39   #12
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Re: Weirdest AIS seen!

I'm sitting in Big Majors Spot anchorage and there's a Ketch here named "Sunday Morning" and its AIS symbol shows up as a helicopter. Never seen that one before.
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Old 13-02-2018, 19:57   #13
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Re: Weirdest AIS seen!

Hi Jeff!

I'm not at all surprised. Thailand instituted some rules a couple years ago requiring all foreign vessels to be equipped with an AIS transponder. They also supposedly required all Thai commercial vessels to have AIS. I've rarely seen any of the Thai fishing vessels transmitting, but lots of passenger speedboats are using it. It looks like they have developed some low cost AIS device for use by fisherman, jet skiers and anyone else that wants to produce false alarms.

This isn't an isolated event. Although, seeing one that was supposedly 4000+ miles away was a first!! These are going off every day, sometimes 3-4 at a time and it's getting worse.

I don't know if you will remember, but Sheri and I met you back in 2003 in Samoa.

Rgleason:

We really need a better way to handle these false alerts. I suspect after a few months, I'll have 100+ MMSI numbers blocked and will never see them again even if they were real. We need a simple way to be able to click on the alert to ignore the alert for a time frame or possibly, until OpenCPN restarts. These are not the same devices that keep showing up. They are different depending on your location. One thing for certain... They are really annoying when a completely worthless SART pops up while you're navigating a narrow channel!
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Old 13-02-2018, 20:07   #14
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Re: Weirdest AIS seen!

Here's another that's unusual. Notice the green airplane symbol near the river on the right side of the screen? It was labeled a SAR Aircraft and was doing over 100kts. I've actually seen 2 of these. On another occasion we saw a helicopter identified as an Aircraft(icon was an airplane) circling a big tanker a few miles offshore of Sumatra. At first we thought it was an actual rescue but as we got closer it appeared to be some kind of a training exercise.
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Old 13-02-2018, 20:38   #15
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Re: Weirdest AIS seen!

Since I've got Jeff's attention, here's another one that you do NOT want to see on your OpenCPN screen. This is from the last time I crossed the Singapore Straits. OpenCPN was reporting 874 AIS targets!!

With this number of targets, the AIS system was almost worthless. Ships doing 20+kts were only updating sporadically. Sometimes 5 minutes between updates. Updating every 5 minutes for a vessel 1/4 mile away doing 20kts is not helpful.

I've crossed the Straits on 2 other occasions when there were about 400 targets and the AIS system was a life saver. It worked as intended and designed, but at nearly 900 targets, it appeared to be overloaded. It seems I did some research and there is a physical limit to the number of targets that the AIS system can handle. I seem to recall it was around 2200.

As governments require more and more vessels to have AIS I worry there will be a breakdown in the effectiveness of the AIS system. On this last trip through the Straits I noticed a number of large tankers and cargo ships at anchor had their AIS systems turned off. I think the commercial operators are aware there is a potential problem.

I'm very interested to read Jeff's comments on this.
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