Any AIS experts out there?

[MK101]

Wondering if anyone can explain what might be happening with our AIS - in particular the fact that when we're not on our boat, she is often alleged (via Marine Traffic and so on) to be in completely different places to where we left her! This is accompanied by other unlikely readings... according to the internet, our 1980s vintage Jeanneau was last seen travelling at 32 knots.

These spoof readings never happen when we are on board (family use MT, or Vesselfinder or whatever to keep an eye on what we're up to, and it's always been accurate when we've actually been switched on, on board). But if we're not there, more often that not our boat pops up (according to the internet) in different places. Often she then 'stays there' for some time. They are always credible in the sense of being on the water, quays, harbours etc - never in the middle of an industrial estate. It doesn't cause us any problems - except some intense nervousness that our boat might have been nicked the first time we saw the discrepancy - but it seems... odd.

All thoughts welcome! (I've no idea if this has relevance to the question or not but we're in the Netherlands, not the UK). MK

 

[lustyd]

Does it generally move to a specific location? Could be someone has entered your ID (or you entered theirs!) and so any time they switch on the record moves to their location.

 

[Refueler]

How are you filtering to get the position of the boat ? usually people use 'Ships name' and then select from the list that pops up...

Are there other boats with same name ?

 

[Alex_Blackwood]

Wondering if anyone can explain what might be happening with our AIS - in particular the fact that when we're not on our boat, she is often alleged (via Marine Traffic and so on) to be in completely different places to where we left her! This is accompanied by other unlikely readings... according to the internet, our 1980s vintage Jeanneau was last seen travelling at 32 knots.

These spoof readings never happen when we are on board (family use MT, or Vesselfinder or whatever to keep an eye on what we're up to, and it's always been accurate when we've actually been switched on, on board). But if we're not there, more often that not our boat pops up (according to the internet) in different places. Often she then 'stays there' for some time. They are always credible in the sense of being on the water, quays, harbours etc - never in the middle of an industrial estate. It doesn't cause us any problems - except some intense nervousness that our boat might have been nicked the first time we saw the discrepancy - but it seems... odd.

All thoughts welcome! (I've no idea if this has relevance to the question or not but we're in the Netherlands, not the UK). MK

From the above we assume that when not on board you are shut down and switched OFF. Therefore it must be the "Tracking" system that is causing the false readings.

 

[MK101]

Does it generally move to a specific location? Could be someone has entered your ID (or you entered theirs!) and so any time they switch on the record moves to their location.

I wondered that. There are a number of locations which pop up - but they don't seem to be coherent. For instance, for a while it was in a relatively confined part of Amsterdam (not accessible to the biggest commercial barges) but one of the recent readings was right in the big locks at Ijmuiden, and there have been 'sitings' in the middle of the commercial docks as well. And there's never a track attached.

 

[Refueler]

From the above we assume that when not on board you are shut down and switched OFF. Therefore it must be the "Tracking" system that is causing the false readings.

Many people don't realise that such as Marine Traffic - a 'target' can be displayed long after the AIS Tx is switched off ... it also works that it can be significant time before you are on the map when AIS Tx is switched on ...

You can test this yourself .... switch on your AIS ... wait till you are plotted on the map. Switch off AIS .... see how long it is before you are no longer plotted ... it can be quick .. or can be hours ... even a day literally.
Do a search for a boat or ship ... then look at the time / date it was updated ...

Full actual real time plot is 1) expensive subscription ... 2) only partially available to normal / pro users ..

 

[MK101]

How are you filtering to get the position of the boat ? usually people use 'Ships name' and then select from the list that pops up...

Are there other boats with same name ?

Actually, as far as we can tell, we are the only one!

 

[MK101]

Many people don't realise that such as Marine Traffic - a 'target' can be displayed long after the AIS Tx is switched off ... it also works that it can be significant time before you are on the map when AIS Tx is switched on ...

You can test this yourself .... switch on your AIS ... wait till you are plotted on the map. Switch off AIS .... see how long it is before you are no longer plotted ... it can be quick .. or can be hours ... even a day literally.
Do a search for a boat or ship ... then look at the time / date it was updated ...

Full actual real time plot is 1) expensive subscription ... 2) only partially available to normal / pro users ..

Yes understood. What's odd though is that we've never been close to some of these locations. As I say it doesn't cause me any trouble - it's just confusing!

 

[Refueler]

Yes understood. What's odd though is that we've never been close to some of these locations. As I say it doesn't cause me any trouble - it's just confusing!

I have to say that as a daily user (Pro) of Marine Traffic - we use it for tracking our ships .... I have never noted spurious locations for any of ours as you have found for your boat. The only awkward we've seen is where ship gets out of tracking and position displayed is old.

Interesting !

 

[dunedin]

AIS is based upon MMSI number, not boat name.
It is possible another vessel is using the same MMSI - due to accidental entry of wrong digits or intentionally using a false identity.

 

[GHA]

when it's wrong does it show up in the wrong place on both vesselfinder & marinetraffic at the same time? Tried a mmsi number search just to see what comes up?

Also, when it's wrong you can see where the reporting station was in marine traffic, just checked a position of mine sent online & it said in the middle of Holland . It wasn't there

 

[onesea]

Absolutely no use at all to your issue, however have you thought about logging the miles sailed?

You just need to get a position in the states and you could have your ocean Yacht Masters!

Other ideas above more valid!

 

[Refueler]

AIS is based upon MMSI number, not boat name.
It is possible another vessel is using the same MMSI - due to accidental entry of wrong digits or intentionally using a false identity.

Correct for AIS itself - but search on Marine Traffic can be via boat name.

Every day I am inputting Ships name to check latest ... or you think I'm dreaming ??

 

[dunedin]

Correct for AIS itself - but search on Marine Traffic can be via boat name.

Every day I am inputting Ships name to check latest ... or you think I'm dreaming ??

Yes you can search using boat name - but the database is based on MMSI. So if the OP is getting spoof locations it could be somebody using the same MMSI on a different vessel.
Marine Traffic keeps a vessel database holding extra data like pictures, and i believe boat name, which it then associates with an MMSI.

 

[AntarcticPilot]

The problem arises because Marine Traffic not only tracks real AIS transponders but also tracks imaginary ones where a user of the app enters details and Marine Traffic tracks their phone. When your real AIS is transmitting, it takes priority, but I'm pretty sure that the ones you see when not on your boat are generated by someone using the app to generate their own tracking information. They have - probably inadvertently - entered details that match yours. My own boat often shows up at Grimsby or Immingham - she has never been there!

Marine Traffic, at least in the incarnations most of us use, is dependent on a network of amateur receiving stations; I am afraid it is also not unknown for them to inject incorrect data, too.

@Refueler probably has a professional subscription, which will be more robust.

 

[Refueler]

Yes you can search using boat name - but the database is based on MMSI. So if the OP is getting spoof locations it could be somebody using the same MMSI on a different vessel.
Marine Traffic keeps a vessel database holding extra data like pictures, and i believe boat name, which it then associates with an MMSI.

Think you are transposing the system ... looking at it from wrong end ...

Yes AIS is transmitted and identity is by MMSI. But that MMSI also gives up from the International Communications Database - the vessel name and details. (Primarily for Rescue services to know what they are dealing with in emergency.... but that's another matter).

But here OP is talking about a boat being displayed in various locations ....

When asking MT for display of a boats location etc. - user inputs boats name - not MMSI. If I put in my boats name - I get a list of 4 or 5 boats ... I choose the one that fits my boats data best ...
If I put in a ships name - I get a list which can be 10 or more ... the range of locations can then be significant - in fact anywhere in the world ... but that's extreme.

Do you input MMSI ? If so - I would suggest you are unusual in that ...

 

[Refueler]

The problem arises because Marine Traffic not only tracks real AIS transponders but also tracks imaginary ones where a user of the app enters details and Marine Traffic tracks their phone. When your real AIS is transmitting, it takes priority, but I'm pretty sure that the ones you see when not on your boat are generated by someone using the app to generate their own tracking information. They have - probably inadvertently - entered details that match yours. My own boat often shows up at Grimsby or Immingham - she has never been there!

Marine Traffic, at least in the incarnations most of us use, is dependent on a network of amateur receiving stations; I am afraid it is also not unknown for them to inject incorrect data, too.

@Refueler probably has a professional subscription, which will be more robust.

Tracks their phone ??? Never heard that one ... not saying it doesn't - just saying I've never heard of it ...

The Network is a combination of Official, Professional and Amateur stations ... along with satelite.

 

[AntarcticPilot]

Tracks their phone ??? Never heard that one ... not saying it doesn't - just saying I've never heard of it ...

The Network is a combination of Official, Professional and Amateur stations ... along with satelite.

But most of us use the free service, which (I think) uses only amateur stations. I may be wrong, but we certainly don't have access to the satellite data. That requires a fairly hefty subscription, which a commercial organisation can easily manage, but which is expensive for a private person.

If using the app, you can certainly set it up to mimic an AIS - I did that when bringing Capricious from the Clyde to East Anglia, so my wife could see where we'd got to. Of course, it requires a mobile signal.

I use it a fair bit to see where a friend who is a ship's officer is!

 

[RunAgroundHard]

Regarding the phone tracking, or rather AIS tracked from cell network, I have recent experience of this. A ship I was involved with could be tracked on the free version in real time, via the cell network as it was quite close to shore for about a week. Then as soon as it moved offshore, in the free version, it stopped tracking and remained more or less where the last cell station reported it to be, until it approached the shore again.

That is how I understood it, happy to be corrected,

 

[Roberto]

Sorry posted this already, one can do funny stuff with Marinetraffic