Live AIS Via Internet

[hoppy]

Originally Posted by mattkab

Wait, you can download porn on the internet?

You can upload it too, but I suspect that is not advisable for most of us here


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[hoppy]

Originally Posted by valhalla360

That's pretty much what some people are suggesting is an option with full AIS. Once you accept that it's not, having data that's a couple minutes old, really loses almost none of the value.

Of course if congested harbors, high speed motor boats are typically very common. On open uncongested waters, AIS is a nice but really not of much use for collission avoidance. Trusting AIS to tell you where boats will be in a congested harbor setting, is foolish.

A couple of minutes old is useless, even slow vessels can move a long way in that time and remember, class A transmits much more often than B and for most people that is what AIS is all about.

I pass other sailing vessels quite closely at times and that is fine, but a big ship I want to keep well clear. When they are travelling at 20 knots and transmitting every few seconds, I want the constant updates. If it's 3 to 5 minutes old info, then there is just no point, I would only use my eyes

If you want to know what AIS Targets there are beyond visible range or at least are just a dot on the horizon, the phone app or web browser is more than sufficient to tell you if you might need to keep an eye on a distant ship


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[jt_kilroy]

That would help, but nothing will ever get rid of it all. The ship to ship component is what is important, all this other functionality is secondary. Hopefully our government doesn't screw it all up in their never ending desire to monitor everything all the time.

Originally Posted by boat_alexandra

what about using lots of ais receivers each with directional antennas? This would help to avoid the problem of two distant ships talking over each other.

[jt_kilroy]

I agree totally with caveat.

I am pretty sure I have had a hand in the deployment in more AIS units (140+) that just about anyone else on this board and this has not been my experience.
I have yet to see a class A unit fail to function as designed. Granted I have not deployed thousands, but I have experienced ZERO failures with class A devices. No doubt that only applies to units made by the suppliers that I use in my business.

Now you sure can't extend that to antennas and cables! The inability of folks to properly construct a cable is mind blowing, to the point that I expect there to be some kind of issue 100% of the time and I am sometimes pleasantly surprised when there is not. But that is the first thing I look at every time.

Originally Posted by valhalla360

The point is even the full blown tool with reciever on the boat fails and in that case an obvious failure is less like to result in a mistake than one that is kind-of good.If you want true collision avoidance, you need second by second data.

[RhythmDoctor]

Originally Posted by valhalla360

...I would much rather have data where the position part of the data is wrong, 1 out of 10 times vs one that is wrong 1 out of 100 times...

That is just wacky. And wrong.

You seem to build your argument entirely on an assumption that all vessels are reporting every 30 seconds. That's just the class B guys. Class A typically reports every 2 seconds or so. Much better and accurate. And it's the Class A guys that I really care about, because they are often stand-on. Since I am usually under sail, the class B guys are usually give-way. There are always exceptions, but as a general rule if a class B vessel is approaching me at 30 knots in close range, I pretty much have to stand on, because even with my motor assisting me, I'm not going to be able to get out of his way. And he can turn on a second's notice, so my best bet is to show my intentions and stick with it.

The big commercial vessels who are going 10-15 knots and unable to turn are the ones that I need to plan ahead to avoid, and fortunately those are the ones transmitting every 2 seconds. In fact, that is exactly why they are required to transmit every 2 seconds. Or in your words, they are transmitting second-by-second data.

[hoppy]

Someone just posted this on another forum detailing the differences between AIS units

http://www.navcen.uscg.gov/pdf/AIS_C...n_By_Class.pdf

Interestingly, someone blasting around at over 23 knots with a Class B transmitter will be sending an update every 5 seconds, not 30 seconds as thought.


internet AIS


If a real AIS is out of your budget, then you are best using these until you can afford AIS

[DotDun]

Originally Posted by hoppy

Someone just posted this on another forum detailing the differences between AIS units

http://www.navcen.uscg.gov/pdf/AIS_C...n_By_Class.pdf

Interestingly, someone blasting around at over 23 knots with a Class B transmitter will be sending an update every 5 seconds, not 30 seconds as thought.

I think (could be wrong) most of the Class B units sold are 'CS', the right-hand column on the document you reference. Hence, 30 second updates.

[hoppy]

Originally Posted by DotDun

I think (could be wrong) most of the Class B units sold are 'CS', the right-hand column on the document you reference. Hence, 30 second updates.

Ooops you are right. I just checked my RM AIS650 manual. It is 30 seconds.

Looks like the Class B SOTDMA is something very new


Panbo: The Marine Electronics Hub: SOTDMA Class B AIS, the "new" middle way?