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AIS last known position

Chaktoura

Member
Joined
7 Feb 2007
Messages
473
Location
Southampton / Chichester
Just curious...
How long do vesselfinder et al continue to broadcast a yachts last known position? Its just that there seems to be a lot of very forgetful people at the moment who turn off their class B AIS at anchor (presumably to save power) and then fail to switch it back on again when they return to their permanent berth, leaving you with a load of last known positions at anchor the previous day. I wonder if they realise this? 🤫
 
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DJE

Well-known member
Joined
21 Jun 2004
Messages
6,869
Location
Fareham
Has switching off the transponder taken over from taking down the ensign as a sunset ritual?
 

Chaktoura

Member
Joined
7 Feb 2007
Messages
473
Location
Southampton / Chichester
Has switching off the transponder taken over from taking down the ensign as a sunset ritual?
That's the thing. It doesnt work. If you switch it off when you arrive, vesselfinder still shows you still sat there in the morning! Doesn't take a genius to figure out you are still there
 

AntarcticPilot

Well-known member
Joined
4 May 2007
Messages
6,675
Location
Cambridge, UK
The various AIS internet services are very error prone. I registered my MMSI with Marine Traffic some time ago. It currently shows my boat as being near Immingham on the river Humber, a place it has never been to! Obviously someone else has registered an incorrect MMSI, which Marine Traffic thinks is me. There's no cross checking in the system, so incorrect MMSIs aren't trapped. The point is that Apps like Marine Traffic see all sorts of data besides real AIS transmissions, and the "fake" AIS data is not verified in any way.
 

Chaktoura

Member
Joined
7 Feb 2007
Messages
473
Location
Southampton / Chichester
The various AIS internet services are very error prone. I registered my MMSI with Marine Traffic some time ago. It currently shows my boat as being near Immingham on the river Humber, a place it has never been to! Obviously someone else has registered an incorrect MMSI, which Marine Traffic thinks is me. There's no cross checking in the system, so incorrect MMSIs aren't trapped. The point is that Apps like Marine Traffic see all sorts of data besides real AIS transmissions, and the "fake" AIS data is not verified in any way.
Appreciate its not perfect but id put money on the vessels showing on vesselfinder in Newtown Creek this morning, with latest position updates from the previous day and no onward track, had spent the night there. The point being if you dont want people to know where you are you need to switch it off before you leave your home berth not when you get there 😀
 
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Just_sayin'

Well-known member
Joined
1 Mar 2014
Messages
1,384
Location
Arrived. But thinking of a bit more east.
The various AIS internet services are very error prone. I registered my MMSI with Marine Traffic some time ago. It currently shows my boat as being near Immingham on the river Humber, a place it has never been to! Obviously someone else has registered an incorrect MMSI, which Marine Traffic thinks is me. There's no cross checking in the system, so incorrect MMSIs aren't trapped. The point is that Apps like Marine Traffic see all sorts of data besides real AIS transmissions, and the "fake" AIS data is not verified in any way.
Found them very helpful when some incorrect photos of my boats appeared:

support@marinetraffic.zendesk.com
 

Sandy

Well-known member
Joined
31 Aug 2011
Messages
15,538
Location
On the Celtic Fringe
The various AIS internet services are very error prone. I registered my MMSI with Marine Traffic some time ago. It currently shows my boat as being near Immingham on the river Humber, a place it has never been to! Obviously someone else has registered an incorrect MMSI, which Marine Traffic thinks is me. There's no cross checking in the system, so incorrect MMSIs aren't trapped. The point is that Apps like Marine Traffic see all sorts of data besides real AIS transmissions, and the "fake" AIS data is not verified in any way.
Odd, I thought they took a data feed.

When I bought my present boat the previous owner had transposed two figures and she was showing up as a Swedish vessel, a few emails later with the AIS manufacturer sorted that out.
 

AntarcticPilot

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Joined
4 May 2007
Messages
6,675
Location
Cambridge, UK
Odd, I thought they took a data feed.

When I bought my present boat the previous owner had transposed two figures and she was showing up as a Swedish vessel, a few emails later with the AIS manufacturer sorted that out.
They do, but in addition they show users of the app as if it was AIS. People can register using any data they like.
 

Stemar

Well-known member
Joined
12 Sep 2001
Messages
12,973
Location
Home - Southampton, Boat - Gosport
Appreciate its not perfect but id put money on the vessels showing on vesselfinder in Newtown Creek this morning, with latest position updates from the previous day and no onward track, had spent the night there. The point being if you dont want people to know where you are you need to switch it off before you leave your home berth not when you get there 😀
Having seen the number of seriously twisted knickers on here, I could be very tempted to go to NC for lunch and turn the AIS off to come home, just as a wind-up ;)
 

bobgarrett

Member
Joined
10 Oct 2005
Messages
755
Location
Oxfordshire
The various AIS internet services are very error prone. I registered my MMSI with Marine Traffic some time ago. It currently shows my boat as being near Immingham on the river Humber, a place it has never been to! Obviously someone else has registered an incorrect MMSI, which Marine Traffic thinks is me. There's no cross checking in the system, so incorrect MMSIs aren't trapped. The point is that Apps like Marine Traffic see all sorts of data besides real AIS transmissions, and the "fake" AIS data is not verified in any way.
I had a similar problem with my yacht being shown between Dover and Calais. This happened at random times for a number of years with Marine Traffic being helpful by "removing the incorrect records" but not fixing the problem. They said it was probably someone with the wrong MMSI number of them but there was never a complete track. Then one day my yacht seemed to be moored in a ferry berth at Dover - I suggested to them that I doubted a ferry would have the wrong MMSI. They took one of their data suppliers off and the problem was fixed.
Bottom line, don't reply in Marine Traffic service as I once did so family could check my location.
 
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