MQ Moving

Tall Stacks 06

And little did we know that would be only 3 months before the end of her cruising days...

AIS Question

There is some talk on this thread about AIS tracking. I have a question; Is AIS reliable? I've looked at the Ohio River several times, and I've never seen any traffic indicated between Cincinnati and Parkersburg. Nor have I seen any traffic below the Louisville area. What gives here? Are there "dead spots" on the river? Maybe we have an expert on this out there.

-Denny Hamilton-

I think the AIS coverage in the Ohio valley is not quite complete. There are dead-spots that aren't covered by relay stations. Madison to Vevay Indiana is mostly dead on AIS, probably because of the high hills along the river and lack of relays. I had some info from Jeff Yates on how anyone with a dedicated internet connection along the rivers could become an AIS relay, but have misplaced it. Dan Owen might have this info as well(?)..

As for marinetraffic.com I think it´s mainly their "problem" with blanc spots. They have to get a signal and they don´t have all relays covered. It´s also not really a live signal they are getting. So usually the signal is a couple of minutes later than reality.

I´m pretty sure that the signals used for real traffic on the rivers is much more accurate and there´s a complete coverage.

Carmen

Not only is this a problem when trying to track vessels from shore, but it is a problem on board the vessels as well. Often vessels show up on the AIS device itself or on the electronic charting system as a number, or they may not even show up at all until they are very close, say a mile or two away, which obviously negates the purpose of the AIS entirely. This sort of thing can happen in any area. Also, since AIS in connected to satellites, the information is not really "real time", though it is very quick. These are the reasons that AIS cannot be relied upon to the exclusion of everything else. That is not to say AIS is unreliable, but it must be used with care.

AIS is one tool, and is a very nice and useful tool, but it does not take the place of visual piloting, radio communication, radar, etc. All are simply tools in the arsenal, useless if one does not have the skills to interpret and use them as part of professional conduct.

Actually, there are holes in the coverage. I was invited to join the network of AIS "reporting stations" to help cover the "hole" in my area, but I didn't have the dedicated internet connection at that time. There was an offer ($50/month) where you would receive a no-cost AIS receiver if you agreed to be setup as a host AIS reporting station to improve coverage. I'm not sure if that offer is still available, but I was not able to take advantage of it at that time, and so there remains reduced coverage between Madison and Vevay... (a problem not limited to marinetraffic.com).