AIS/Marine Traffic "image" not moving??

[Robert Wilson]

The last twice I've been out in my home waters my trace as shown on Marine Traffic has been intermittent or not moved.
The image was also visible on my mobile/Marine Traffic app in one location for three days, even thought I was on the mooring all the time.

My boat shows up on my plotter screen and is accurate to my actual position.

Also, occasionally, the Stornoway Ferry has been visual to me, but not showing on the plotter screen.

Any thoughts on what might have gone awry?

I'm more concerned about my own trace not showing, as this may mean I'm not visible to other craft/shore people monitoring me (for safety etc)

TIA

 

[[70521]]

Marine Traffic relies on shorebased receiving stations and is not part of the AIS transmission/receiving system. One reason why when posters say I've got this exciting new APP on my phone we all say it is a toy and get a proper transceiver/receiver.

 

[Robert Wilson]

Sandy, I accept what you say, but in the four years since I fitted the AIS and the plotter (

NMEA etc)​

, the trace has never jammed or remained "on screen" on my mobile. Neither have "shore" folk reported this problem.
I can't comment on whether or not I've been visible on others' screens as I haven't had the chance to ask/test.

What do you mean by a "proper transceiver/receiver".

Thank you. ​

 

[[70521]]

So you are happily pinging out AIS transmissions, seen by other ships.

A packet of data arrives at the radio mast on top of "The Jolly Sailor" pub but it has been raining hard and the connection to the telephone system has got damp or there is a problem with the exchange or the router has been turned off that turns the AIS signal into something that can be send down the internet to the Marine Traffic servers, I think they are part of a Greek University. A lot of variables to go wrong there.

 

[bobgarrett]

Not just that problem of Intermittant Receivers on shore, they can also get the data seriously wrong.
One of their sites sometimes reports my yacht as being on its way from Dover to Calais or vice versa. On investigation it seems one of their sites screws up the data for ferries and picks random yachts to assign to it. Each time I report it they take that station off line to solve it. Then a year or so later they connect him again and the data is screwed again for a few weeks before they take him off again!
Not a serious service. It may be useful but not considered reliable.

 

[Robert Wilson]

Not just that problem of Intermittant Receivers on shore, they can also get the data seriously wrong.
One of their sites sometimes reports my yacht as being on its way from Dover to Calais or vice versa. On investigation it seems one of their sites screws up the data for ferries and picks random yachts to assign to it. Each time I report it they take that station off line to solve it. Then a year or so later they connect him again and the data is screwed again for a few weeks before they take him off again!
Not a serious service. It may be useful but not considered reliable.

Of course, the old techniques are indispensable - i.e. keeping a proper look-out at all times.
However, my shore people do like to see what I'm doing and where I'm going (faithful bunch!!)
And I like to "read about" what craft that is which is in "my" sea!

I'm still perplexed as to why, suddenly, my image hadn't moved for three days.

 

[duncan99210]

It’s the nature of the beast, as others have said. The shore based coverage round Greece is patchy. In some areas, our signal shows up where we are in real time. In other areas, we disappear. More often, Marine Traffic will simply continue to display our last position until we reappear on another shore station’s input.
Marine Traffic shows our current position as Preveza Marina. It shows an accurate time for a last position as it was just before we turned the AIS off. However, we turned the AIS back on three days later to move to Ionion Yard on the other side of the strait. Despite having the set on for over an shore based people didn’t pick us up..... It’s a fun app/website but doesn’t reflect reality very well.

 

[prv]

I'm still perplexed as to why, suddenly, my image hadn't moved for three days.

The hobbyist whose receiver normally covers your area has gone on holiday and his mum has unplugged "that pile of junk" in his room.

Pete

 

[Lon nan Gruagach]

Of course, the old techniques are indispensable - i.e. keeping a proper look-out at all times.
However, my shore people do like to see what I'm doing and where I'm going (faithful bunch!!)
And I like to "read about" what craft that is which is in "my" sea!

I'm still perplexed as to why, suddenly, my image hadn't moved for three days.

Ahh, technology is a wonderful thing, and techbabble even more so.
What has been said a few times, but perhaps in geekish is that Marine Traffic rely on many many (amateur) shore based receivers which relay your (totally) reliable AIS transmission to Marine Traffic HQ.
Sometimes, as with most volunteer services they drop out from time to time. This is one of those times for the shore station local to where you are.
If you want to keep nearest and dearest up to date on which pub you re absconded to in a more reliable fashion then you will have to "roll your own" and keep it ship shape and Bristol fashion.
Whats required is an AIS receiver, something that can monitor all the signals it receives and a web dohickey to make that visible to all and sundry. You place all that on the shore where the leccy and tinterweb are guaranteed.
Or.. If you are always within mobile data coverage you can use any of the wayward teenager tracking systems.

 

[prv]

Whats required is an AIS receiver, something that can monitor all the signals it receives and a web dohickey to make that visible to all and sundry. You place all that on the shore where the leccy and tinterweb are guaranteed.

Then you can also feed that data into Marine Traffic and become another of their volunteer stations improving the coverage

Pete

 

[Robert Wilson]

Ahh, technology is a wonderful thing, and techbabble even more so.
What has been said a few times, but perhaps in geekish is that Marine Traffic rely on many many (amateur) shore based receivers which relay your (totally) reliable AIS transmission to Marine Traffic HQ.
Sometimes, as with most volunteer services they drop out from time to time. This is one of those times for the shore station local to where you are.
If you want to keep nearest and dearest up to date on which pub you re absconded to in a more reliable fashion then you will have to "roll your own" and keep it ship shape and Bristol fashion.
Whats required is an AIS receiver, something that can monitor all the signals it receives and a web dohickey to make that visible to all and sundry. You place all that on the shore where the leccy and tinterweb are guaranteed.
Or.. If you are always within mobile data coverage you can use any of the wayward teenager tracking systems.

Gotcha.
Thanks, I now understand.

As posted above, the local techky must have gone away for the winter and his mum is still trying to his bedroom door open...….!

 

[BrianH]

I am lagoon-berthed in NE Italy and my nearest MarineTraffic receiver is in Koper, Slovenia more than 25nm across the northern Adriatic. My AIS antenna is pushpit mounted and somewhat shielded by a wind-generator pole, so not too efficient for long-distance coverage ... but efficient enough to be fully functional for its purpose of close-distance collision avoidance.

Only when I emerge from the lagoon entrance 5nm from my marina can I expect the Koper receiver to relay my presence to MarineTraffic and be shown on the web-site display.

VesselFinder however, without revealing their contributing receivers as MarinTraffic does (click on ship icon to see "AIS Source:" ), reports my position consistently and seems far more able to report targets throughout the Mediterranean. Probably they have a receiver closer to me in Italy but are too coy to publicise where it is.