AiS range !!!!!!!!!!!

[mhouse]

I must say I am well please with my AIS.




Picked up this last year . It took a lot of zooming out on the plotter to find it.
My previous furthest was 4500 miles.
When should I have taken avoiding action ?

 

[RichardS]

My furthest AIS contact was 500 miles which I thought gave me a good enough safety margin.

Richard

 

[prv]

It took a lot of zooming out on the plotter to find it.

So where was it?

My first guess was “zero island” - the place off Africa where the Prime Meridian crosses the equator and thousands of uninitialised GPS receivers claim to be - but the distance is too big even for that.

Is there an Australian AIS manufacturer who use their office location as some sort of test value?

Pete

 

[Mendit]

It must have been very good cmdts for signal bounce. The plotter was cluttered the North sea was full. From the Ore I was picking up ships from the Humber to Calais docks.

 

[lw395]

THLS = Trinity house lightship?
'Virtual' AIS means the beacon does not actually transmit from its charted position.
'Test' = 'apprentice is fiddling with something', ignore it.

 

[prv]

THLS = Trinity house lightship?
'Virtual' AIS means the beacon does not actually transmit from its charted position.
'Test' = 'apprentice is fiddling with something', ignore it.

Sure - it’s the MMSI below, starting with 286, that we’re looking at. That’s reporting a position almost 10,000 miles away.

Clearly that one’s not transmitting from the location it’s reporting, so I was curious where it was claiming to be and whether there was anything significant about that location.

The Trinity House ones could be perfectly legit, especially if the antenna is omnidirectional and the OP is on the opposite side of it from the reported location.

Pete

 

[prv]

It must have been very good cmdts for signal bounce. The plotter was cluttered the North sea was full. From the Ore I was picking up ships from the Humber to Calais docks.

The OP wasn’t picking up signals from the other side of the world, however good the VHF conditions

Since the transmitter wasn’t sending its own position, it could have been half a mile away for all we know.

Pete

 

[pyrojames]

I have seen signals from vessels with the (presumably) correct latitude, but 0 longtitude. It gives rise to all sorts of spurious positions over the land.

 

[wully1]

There is often a log jam of AIS positions at the entrance to the narrows in Loch Sunart as there is no receiving station in the Loch and VHF propagation is poor.

( Also Navionics / GPS positioning is well out in the narrows...)