AIS - essential kit these days for channel crossing?

RichardS said:
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So, on that point GHA, please tell us all why you believe that an AIS transponder does not receive and transmit AIS data. :rolleyes:

Richard
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I don't think that he, or anyone else, ever said any such thing here... It is certainly true that they are often referred to as "transponders", but it is not really the correct term. A "transponder" is a device which receives a signal and transmits a response to it - that's where the "pon" in the name comes from. AIS does not work that way - the transmit and receive sides are independent of each other with the small qualification that the transmit side does take notice of the timing of received packets in order to reduce the probability of collisions between multiple transmitters. The transmit side does not wait for an incoming packet before transmitting anything - in the way that an active radar reflector does, for example.
 
awol said:
[pedant] An AIS device that receives and transmits is NOT a "transponder" - you ignorant lot![/pedant]
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maby said:
I don't think that he, or anyone else, ever said any such thing here....
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All I said was that a device which receives and transmits is a transponder ..... which is exactly the same as saying that a transponder receives and transmits AIS data, although you need to go back to post #30, quoted above, to follow it through.

Awol and GHA will simply not accept this statement of fact. :)

Richard
 
awol said:
Which despite RichardS's assertion does not describe an AIS transceiver as presently used by ships and other craft.
Pedantic, indeed yes, but if words are used wrongly, credibility in the message is diminished as is that of the sender. Arguing that "we all know exactly what we mean" is just another of the dumbing down, anti-expert attitudes that is only too prevalent in present times.
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SRT are the experts IMHO, they call class B in particular a 'transponder'.
I think the transmission is responding to the 'population' of class A emitters as a whole, is a legitimate view of what is going on in general.
AIUI, class b devices can also be polled by some class A devices, which makes them transponders by most definitions.


You can beat yourself up too much with defintions of technical terms.
 
RichardS said:
All I said was that a device which receives and transmits is a transponder ..... ...


Richard
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That is certainly not true! I have a walkie-talkie on the table next to me as I type this - it both transmits and receives, but it is a "transceiver", not a "transponder" - it does not automatically transmit anything in response to receiving something. Trust me on this - I'm a radio engineer...
 
maby said:
That is certainly not true! I have a walkie-talkie on the table next to me as I type this - it both transmits and receives, but it is a "transceiver", not a "transponder" - it does not automatically transmit anything in response to receiving something. Trust me on this - I'm a radio engineer...
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Jeez. This discussion is getting more like kindergarten.

We are discussing AIS devices (see thread title if you need confirmation) and I have repeatedly said that an AIS device, like the ones which are being discussed in this thread, which receives and transmits includes both a transponder/transceiver depending upon your position on this discussion. :)

Please go back to post #55 if you really need the detailed explanation, or simply refer to the second part of my quoted statement which you understandably deleted. :rolleyes:

Richard
 
Interesting comments,

I've made a number of crossing over the years without AIS or Radar and poor visibility has always worried me as it can come down out of nowhere.
Last year I bit the bullet and bought a DSC with AIS built in it had it's own spiliter so basically plug and play and i'm delighted with it.
On a night crossing mid channel 2 large cruise ships came up crossing S to N. AIS allowed me to see their exact course and CPA which was very reassuring.
Total cost about £350 and well worth it for peace of mind.
 
Further to a previous discussion, here's ' The flying lifeboat ' - I have asked a chum who used to fly Nimrods if the new Poseidons carry liferafts to drop, he's enquiring and getting back to us, though I may have lost it by the time they decide I'm worth an expensive liferaft ! :)

https://en.wikipedia.org/wiki/Airborne_lifeboat

- Edit - wrong thread but I suppose it may be of interest to some, you can see the evolution of the Fairey Atalanta. :)
 
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I prefer pencil and paper over GPS and my AIS stays off unless I'm crossing the channel but for crossing traffic it's been a game changer. No more stress of trying to guess ship speeds and trying to work out whether the bouncing around bearing is changing, I can see when something has made its 2 degree heading change to avoid me and concentrate on the next ship and the next one. Never mind poor vis, it's taken most of the stress out of a daylight crossing. The only reason I'd care about losing GPS data on a cross channel is if it happened in the middle bit where I want to plot AIS targets. Essential? No. Makes the crossing vastly more enjoyable? yes.

If I never crossed the channel or other high-density offshore commercial routes AIS would be a waste of money and space but for this specific purpose it's ace.
 
awol said:
Which despite RichardS's assertion does not describe an AIS transceiver as presently used by ships and other craft.
Pedantic, indeed yes, but if words are used wrongly, credibility in the message is diminished as is that of the sender. Arguing that "we all know exactly what we mean" is just another of the dumbing down, anti-expert attitudes that is only too prevalent in present times.
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You make a reasonable point but if you are committed to not using words wrongly then please reconsider your assertion that "An AIS device that receives and transmits is NOT a transponder" because that is not only pedantic, it is wrong. :)

Richard
 
RichardS said:
You make a reasonable point but if you are committed to not using words wrongly then please reconsider your assertion that "An AIS device that receives and transmits is NOT a transponder" because that is not only pedantic, it is wrong. :)

Richard
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Give up Richard, just because it transmits and receives, does not make it a transponder. And try not to denigrate people that happen to disagree with you.
 
Seajet said:
What does the panel think of the ICOM AIS kit & display ?
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(a) I sail short handed and am usually helming
(b) I like to be able to instantly compare what I can see on the screen with what I can see

AIS targets plotted on a plotter at the helm are far more useful to me than a radar style display at the chart table so it's a "no" from me.
 
DownWest said:
Give up Richard, just because it transmits and receives, does not make it a transponder. And try not to denigrate people that happen to disagree with you.
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Errrrr .... check out my post #38 please. A perfectly friendly post with smilies as a semi-serious response to Awol calling us "ignorant" with a total absence of smilies. Then see who starts with the denigrating "it's your problem" comments, sans smiley.

Then, come back on here and tell us all who started the denigration and who continued it in his totally unprovoked assault in his post #54. I look forward to your conclusions. :)

By the way, if you wish to discuss the technical issue, please note that "just because it transmits and receives, does not make it a transponder" and neither does it make it a transceiver. :encouragement:

Richard
 
laika said:
(a) I sail short handed and am usually helming
(b) I like to be able to instantly compare what I can see on the screen with what I can see

AIS targets plotted on a plotter at the helm are far more useful to me than a radar style display at the chart table so it's a "no" from me.
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Thanks but I have a swing out display panel visible from the cockpit usually, or from below if cowering in bad weather - so I'm really asking if anyone knows how the ICOM AIS performs, is it worth the £630 ?

I'd really like the display ' it's over there on such and such course ' to make my course decisions rather than relying on an RTE I can't tell if ships have picked up.

Sorry RTE fans but I always like active rather than passive stuff for things like crossing the Channel - now I'm older I need all the help I can get. :rolleyes:
 
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