Balti kábeles elemzés/összefoglalás:
Written by Tom Sharpe who was a Royal Navy officer for 27 years and captained four different warships
Two weekends ago data cables in the Baltic Sea – one between Sweden and Lithuania, the other Finland and Germany – were severed.
At the same time, ever vigilant maritime open-source intelligence gatherers (people looking at the internet) spotted that the Yi Peng 3, a Chinese-registered merchant vessel with a Russian captain, on its way from the Russian port of Ust-Luga to Port Said in Egypt, was above both cables at around the time they were severed.
What happened next was largely predictable. The online commentators were quick to judge, noting the vessel’s unusual movements and suggesting that it had slowed down to drag its anchor across the cables. Their view was clear, “if it looks like a duck and quacks like a duck, it’s a duck”. Pictures are now emerging of the ship showing twisted anchor flukes – guilty as charged.
Expert maritime analysts such as Sal Mercogliano were less quick to judge. As ever with events at sea, things are rarely as straightforward as the initial reports suggest.
Yi Peng’s movements from sailing on 11 November are a little unusual; going to anchor straight from alongside, then moving anchorage nearer the port – but then many shipping movements are unusual to anyone outside the ship or company, we just never take much notice. She then gets underway heading along the traffic lanes at about 9-10 knots until 17 November when she slows to seven knots. Again, this is a little odd but with 30 knots of wind on the ship’s head and 2.5-metre swells, hardly inexplicable.
As she crosses the first cable to be cut early on the 17th she is still doing just under seven knots. By midday, ship-tracking websites are no longer receiving updates from her Automatic Identification System (AIS) transponder and this remains the case for about seven hours. Then updates start coming through again and her speed during the dark period is estimated as seven knots.
It should be noted at this point that while AIS is invaluable as an aid to help avoid collisions (which is what it was designed for) it is often not accurate or reliable enough to assist in detailed investigations. I’m occasionally surprised by the weight attached to it during Russian ‘dark fleet’ investigations – back when I was doing fishery protection, it was not deemed reliable enough to be used as evidence in court. In other words, AIS data is useful but should not be treated as a smoking gun.
It should also be borne in mind that normally a ship’s AIS equipment transmits its data only by VHF radio. This means that other ships nearby can receive it – this is, after all, primarily what the system is for. Ship-tracking websites receive much of their data via shore-based AIS receivers connected to the internet, typically run by volunteer enthusiasts. The ship-tracking services will often give away receivers for free to people in places they would like to cover.
More and more these days, there are likely to be satellites overhead which will pick up AIS signals even if no shore station receives them, but not all such satellite constellations make that data available to others, and not all tracker websites use – or can afford – all the available satellite data. Also, satellite AIS data often takes a long time to update, as there may be a wait for another satellite to pass over the area.
VHF without satellites involved is generally fairly short ranging, and sometimes there may be no shore station that can pick up a ship’s transmissions. In that case it may disappear from the tracking websites, even if its transponder is actually on and transmitting. A ship ‘going dark’ doesn’t always mean that its transponder has been turned off on purpose.