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Old 29-05-2006, 07:36   #46
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Coot, if it was my comment you were responding to, I apologize it was meant in jest. I should have put a on it. Of course that doesn't mean Homeland Security won't pick up on it. After all they have secured our coast line from all those terrorist with yachts. If it weren't for their checkin procedures our coast line would be constantly bombarded by suicide Catalinas. (remembered this time)

Phiggins, I don't know what the first 3 fields are, they don't seem to ever change. The fourth field I believe is the channel ID for the frequency on which the message was received. I think this designation (A or B) is specific to NASA, as I believe the ITU specification refers to the frequencies as channel 1 and 2. If you have a late model NASA engine it will toggle between the channels every 36 seconds so you should see this field change periodically. You got a lot further than I if you can decode the data field. I found the document on the ITU website that defines the message format, but they want 25 Swiss Francs for the privledge. I wasn't that interested.

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Old 29-05-2006, 08:08   #47
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John, I got the information from the ITU site to decode the AIS data field. That site actual allows you 3 free downloads but you have to register for a special userid and password, their site explains how. You would think the document would explain the other fields but if it does I can't find it. Those other fields do change:

!AIVDM,2,1,9,A,55N0dR01gdl`dpH@0010th5:1@EP5<000000001@000,0*78

which is from the sample file from the Fugawi website. I know the sample files from the NASA site do not change those fields, always 1,1,,.

To decode the AIS data you really need a program as it uses 6 bit ASCII. I'm writing one just to see if I can and also to possibly write a program to translate the AIS (VDM) data to ARPA (TTM) so I can possibly display it on my Furuno radar that doesn't support AIS (I think the new Furuno radar units do support AIS but I not willing to pay another $3000+ for one). Plan to test a basic program today to see if my radar will accept the translated data.
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Old 29-05-2006, 08:21   #48
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Phiggins,
Thanks for the ITU info. I saw the signup screen, but just assumed it would take me to membership fee screen. I'll check it out.
The problem I believe with the other fields is they are NMEA specified and the ITU doesn't have anything to do with it. I think we all know NMEA does not give anything away for free. Since you are a Fugawi user you might try calling their technical support and see if they would give you the information on the fields.
I certainly don't recommend trying to get the info out of NASA. I know at least three of people in addition to myself, who have tried to get technical support form NASA by email or telephone without a response. As far as I can tell the telephone number on their website is not connected to a real phone or it is in the office of someone who long ago left the company.

Good luck with your programming effort.

John
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Old 29-05-2006, 10:34   #49
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If you download those recommendations for ITU-R M.1371 on www.itu.int get the newest revision and the old one if you want to see all the sentences.

I think I've figured out those fields. They indicate the number of sentences in a message. For instance the sentence I sent you in my previous message:
!AIVDM,2,1,9,A,55N0dR01gdl`dpH@0010th5:1@EP5<000000001@000,0*78
is followed by:
!AIVDM,2,2,9,A,004000S000000000000000000000,2*7A
So the 1st field (2) says there are two sentences to this message and the second field says this is sentence number x of 2 .
I think the third field just identifies which sentence the message belongs to.

Haven't figured out the one byte in the sixth field.
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Old 29-05-2006, 14:45   #50
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"with a state requirement for smallboats being required to have VHF or EPIRB if going one mile offshore." That one baffles me. How does a state get any legal authority to require *anything* in federal/international waters, where the states have no jurisdiction? Something different in Hawaii?
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Old 29-05-2006, 14:51   #51
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hellosailor,
I think the requirement is at least partially justified because there are a number of vessels who head off-shore and then require a very expensive search and rescue. Those two items are pretty basic to being found and rescued. If that is all that is required it doesn't sound very onerous, stuff that any cruising sailboat should have anyway. Of course you can always sneak away in the night.

Oh, and I don't think 1 mile puts you in international waters.

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Old 29-05-2006, 15:33   #52
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Mark-
"How can you improve "homeland security" by requiring all cruising boats to carry AIS?" Oh, that's an easy one. Any terrorist would of course program their AIS transponder to read "TERRORIST ATTACKING" so any dumy would be able to spot them and intercept them. I say any dummy because we all know, the dog and pony show designed to mollify the sheep is more important--and way less expensive--than real Homeland Security. (sigh).

JT-
While it may or may not be cost effective to require that equipment, I wasn't aware that any states could regulate equipment carried by boats going offshore to any particular distance. Inland waterways, maybe. But offshore? Outside the COLREGS demarcation lines? I thought, perhaps incorrectly, that was federal only. Unless Hawaii is requiring this for *motor*vehicles* which are registered in that state, which is the way that most US states regulate boats with engines or auxiliary engines--but not boats per se.

Just curious to learn what the real basis under this is.

Personally, I think we need some kind of an opt-in/opt-out registry, i.e. where you could sign up and say "I am/not carrying the suggested safety equipment...Please don't bother responding to my distress calls...And if I don't have the equipment, I agree to pay you all rescue expenses plus overtime for those nice folks who had to come get me."

You know, something that gives real sailors their freedom, and gives the SAR folks a clear line to know when they can stay home and let the idiots prove Darwin knew his stuff.<G>
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Old 29-05-2006, 15:57   #53
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Hellosailor,
In the words of our former president, "I feel your pain"
Unfortunately in the litiguous society we live "opting out" doesn't seem to be an option. Just like those "Do not resuscitate" directions we put in all sorts of legal documents, the health industry is less concerned about out our sueing them for keeping us alive than they are of someone else sueing them for letting us die. The same way with the rescue services and the state and federal agencies that fund them. So buy an EPRB, but not the battery. Make that your statement. The battery is a major portion of the cost, and without it they'll never come looking for you. I know it's caving to the bureaucrats, but sailing, like life, is one compromise after another.

John
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Old 29-05-2006, 19:22   #54
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Homeland security for small boats is a joke

Hellosailor,

The only thing homeland security has done for small boats is increase the frustration level of the operators by implementing meaningless regulations and procedures that only the law abiding adhere to. Case in point: if there is more than one cruise ship in Government Cut going into Miami, all small boats cannot go through but must take a detour behind Dodge Island. Last fall, going into Miami, I was right up to the cruise ships before I realised that there was more than one cruise ship tied up there. Nevertheless I had to turn around and take the detour. The reporting requirements are just as silly. The bad guys would simple not report in, the good guys, of course, have to jump through all the hoops. I guess the authorities have to be seen as doing something, no matter how asinine it might be. Nobody seems to be analysing these measures as to their effectiveness. The "optics" are what counts. End of rant. Have a nice day.
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Old 29-05-2006, 19:54   #55
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JT-
Working from an outboard platform over 34F waters, the man in charge asked us to please wear life jackets, over or under our parkas as we chose. Since survival time in the water was less than half of what "stop and recover him" time would have been, someone asked why bother with the life jackets?

"Because someone is going to come out in the cold and rain trying to locate and recover your bodies, and the sooner they can do that, the sooner they can go home and get warm and dry again, so you wear it as a courtesy to THEM."

I couldn't argue with that, I've been in favor of wearing life jackets ever since. As a courtesy to those underpaid sons of sailors who do one damn fine job, in the worst of circumstances.

Although I'm not sure being eaten by worms would be any better or worse than being eaten by crabs.<G>
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Old 29-05-2006, 22:46   #56
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Quote:
Originally Posted by knottybuoyz
It was my understanding that AIS on recreational vessels would be "receive only" and not required to carry a transponder. Maybe that was my mis-understanding.
I refer to an earlier message in the thread:
Quote:
Originally Posted by jstevens
There was a piece in Lat 38 about Mexico wanting all cruisers to have an AIS transceiver (or something equivalent), but that seem to be a still-birth.
All the currently available systems that I know of for small boats are receive only. In principle, a transmitting AIS system should be possible to build for not much more than the cost of a marine VHF, not including design costs and profit. (And ignoring regulatory issues...)

Quote:
Originally Posted by jstevens
Coot, if it was my comment you were responding to, I apologize it was meant in jest. I should have put a on it. Of course that doesn't mean Homeland Security won't pick up on it.
If your jest (and other jests) were all there was to it, I would not be concerned. But I've also seen references to it in mainstream media. For example, NOAA is building a system to forward AIS data received by offshore data bouys, under the guise of homeland security.

There are good uses for AIS, like collision avoidance and coordination of services (e.g. have a customs agent arriving at the dock at the same time as the ship). It just isn't a way to track hostile entities.
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Old 30-05-2006, 07:07   #57
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Back to the wire after a few days off.

John- your message didn't seem like a rant. In fact I'm swinging to the AIS side of the argument pretty quickly. At least I will be considering AIS compatibility when I do purchase that chartplotter.


Over the weekend I ran across a HS postion paper that stated the need for all boats in US Costal Waters to have AIS transceivers on board. It should be on the web somewhere and if I can get the link I will post it. Essentially the paper said that adding AIS to all vessels below 65 feet and under 300 gross tons was a 'phase two' implementation. Meaning that they have to pull off phase one first. While this may or may not seem foolish from a security aspect, don't forget the 'pork' angle. If this requirement is implemented then someone stands to make a bundle selling AIS transmitters.

Finally there was a mention of licensing for boat operators. I would like to see a nonmandetory, noncommecial yachting license in the US. I understand that the UK has a Yachtmaster that is similar. Beyond the simple personal accomplishment accomplishement of getting the license, it should have some currency with USCG boarding parties and hopefully recognition with foreign officials.
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Old 30-05-2006, 09:56   #58
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Originally Posted by Pura Vida
Over the weekend I ran across a HS postion paper that stated the need for all boats in US Costal Waters to have AIS transceivers on board.
Continuous transmit on VHF is going to take a considerable amount of power during a journey. I do hope this position paper addresses the safety implications of loss of GPS and VHF and other essential items when the power fails due to such a stupid and irrational requirement.
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Old 30-05-2006, 11:01   #59
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My guess all this official discussion of requiring a Class B transponder on recreational vessels will die for other than the logical reasons we cruiser might put forward. It will die because the commercial users don't want to see their displays cluttered up with small craft. So although I have the same concern as most of us, that Homeland Security does not respond to logic, I do believe the commercial users will and they do not want to have to monitor us. So a mandated AIS transponder on my boat is a concern way below that of the bird flu and tax assessements in Europe. The former being a very low concern, the later very high.

John
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Old 30-05-2006, 11:17   #60
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Talbot - it was a high level warm and fuzzy with no talk about how to make it work. The AIS content took a paragraph in a long document.

John - I have to agree... I"m far more concerned about the Internal Revenue Service than AIS or HS putting a dent in my crusing plans.
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