BLUEMOMENT

Fancy a discussion on IRPCS? Or even a conspiracy?

On Saturday 4 August 2012 at 0800hrs BST, I had the VHF on 16 whilst waiting for the 0810 forecast.

I overheard a exchange between Isle of Arran and Statengracht on 16 – actually I could only hear Isle of Arran and had to guess the response from Statengracht.

There was mention of “I intend to abide by the regulations of IRPCS” and “what are your intentions?” and I was intrigued enough to search out the AIS data.

Have a look at these scenes

http://www.aisliverpool.org.uk/historymap.php?map=IsleofArran&hh=7&mm=40&date=20120804

http://www.aisliverpool.org.uk/historymap.php?map=IsleofArran&hh=7&mm=50&date=20120804

http://www.aisliverpool.org.uk/historymap.php?map=IsleofArran&hh=8&mm=0&date=20120804

http://www.aisliverpool.org.uk/historymap.php?map=BrodickBay&hh=8&mm=0&date=20120804

http://www.aisliverpool.org.uk/historymap.php?map=BrodickBay&hh=8&mm=10&date=20120804

http://www.aisliverpool.org.uk/historymap.php?map=BrodickBay&hh=8&mm=20&date=20120804

So what happened to the AIS signals at 0800? This was the time of the VHF transmissions. Would this block out the AIS? Have the positions / speeds been deliberately ‘lost’ by someone? Knowing what was being said, I would have found the positions at 0800 very interesting. Look at the speed of Isle of Arran at 0810.

Ash

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"This is a sailing Forum"

I'm surprised the commercial traffic stopped (if it did) but if the aerial was common to both the VHF and the AIS, the ais data would be lost/suppressed during voice transmission.

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Just because you're paranoid
doesn't mean they're not out to get you.

These AIS plots are all done by amateurs who stick up receivers and upload the data to various servers. I expect the receiving station just went off line or had some other glitch. The Caledonian Isles, Argyle, Loch Shira and Cameron all disappeared as well. In fact the only two which didn't were the Zagreb (moored at Hunterston?) and the Paul Schulte (anchored off Brodick?).

In short: I sure the signals were there and just weren't logged.

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Never attribute to malice that which is adequately explained by stupidity - Hanlon's Razor
But don't rule out malice - First Corollary to Hanlon's Razor

Is there any other site that provides a 'history' as opposed to 'live' AIS information?

Can you get Lat/Lon info so that positions can be plotted on a chart?

Ash

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"This is a sailing Forum"