Real, Synthetic & Virtual AIS AtoNs, can you see them?

[knuterikt]

Not wanting to hijack this thread http://www.ybw.com/forums/showthread.php?418688-Garmin-Plotters-and-Atons

This is a nice article describing all he useful information that can be displayed by an AIS AtoN.
http://www.panbo.com/archives/2015/01/real_synthetic_virtual_ais_atons_can_you_see_them_.html.

By putting an AIS beacon on a buoy It could report when it is out of it's assigned position or it would not be visible at all if lost.
AIS can also be used to display navigation warnings.

 

[tillergirl]

First I need to declare myself a Luddite. I have no plotter.

I can understand that a virtual AtoN can be useful. Take the Westerschelde for example where they are being tested by the Dutch. The channel moves frequently and as a consequence they are frequently moving the channel markers. What could be better than to save the money spent on the sinker, chain and buoy and have a survey vessel that defines the channel and provides the coordinates for the location of virtual AtoN which are then broadcast. Cheaper, quicker. Bit of a b*gg*r if you don't have a plotter, nor one that doesn't harvest AIS properly - or if your power does down.

But an AIS on an existing AtoN? So let's say there is one on the Sunk Inner (which there is). I trundle along and my plotter shows where the Sunk Inner is as a standard AtoN. But it also shows an AIS response. Not sure that has helped me. I knew where I was, I knew where the Sunk Inner was and I guess the AIS just tells me it hasn't moved out of position. I guess though it could transmit 'my lights are not working' if it can add nav. warnings. Useful. But that is already probably a Radio Nav Warning.

This time, however, I approach the Sunk Inner and I have the plotter telling me it is here and the AIS telling me it is half a mile away. Logic tells me that the Sunk Inner must have moved (if the transponder is actually on the AtoN - which the article suggests it doesn't need to be). Now how do I know whether the move is deliberate or not (assuming I don't follow NtM)? Presumably I would look for any nav. data also being broadcast by the AIS. In which case it is pretty important that my plotter (if I had one) showed all the data available. And going back to the linked thread, I understand that is not always the case.

Telling Trinity House that it is off position? Is this a useful function? I wonder. When I visited Trinity House a couple of years ago, I saw in their control room, a guy monitoring the country's AtoN. I cannot remember all the detail now but he certainly could tell if a light failed so there is something in AtoNs already sending data to TH. In which case, perhaps AIS is being looked at as a better option.

This is the current (2012) TH policy:

4.6 Automatic Identification System
AIS technology can significantly enhance and complement existing Aids to Navigation. In
particular, AIS technology can be used in the following ways:
■ To provide AtoN identity and AtoN status confirmation to the mariner
■ As Real or Synthetic AIS transmitted on behalf of an existing AtoN
■ As Virtual AIS AtoN, where no physical AtoN exists, for example for use in wreck marking
prior to deploying buoys, mitigating further the risk to mariners
■ To broadcast AtoN monitoring for the service provider
■ To facilitate traffic analysis by AtoN providers to assist in the provision of the appropriate
level of service and mix of AtoN
Under SOLAS, all ships of 300 gross tonnes and upwards engaged on international voyages, cargo
ships of 500 gross tonnes and upwards not engaged on international voyages and passenger ships
irrespective of size are already required to be fitted with an Automatic Identification System
(AIS). In addition, ships not engaged on international voyages and constructed before 1 July
2002 have also been required to be equipped with AIS since 1 July 2008. Over and above these
rules, there are now some international authorities that require all vessels transiting their area
of jurisdiction to be fitted with AIS.
As AIS develops, the GLA will seek to exploit all these benefits to enhance their service delivery
to the mariner by applying AIS technology to selected AtoNs. The use of AIS as an AtoN will have
a direct and positive financial impact on our service provision. Under certain circumstances AIS
may provide an appropriate alternative to permanent or temporary physical AtoNs. However, this
is not seen as a means of reducing the cost of service provision.
In order to maximise the opportunities presented by AIS, the GLA will:
■ Enable an operational AIS virtual AtoN service
■ Work closely alongside the MCA and IRCG to establish the necessary inter-agency service
level agreements
■ Continue our involvement in the development of relevant standards through IMO, IALA,
IEC and ITU
■ Monitor the development of new and evolving AIS technologies and assess their ability to
support new value added AtoN services to the user

 

[Lucky Duck]

Sort of following on from this, I am not at all clear on the purpose of the land based stations such as the Radar Tower between Walton on the Naze and Clacton and on the Bawdsey coastguard radio tower.