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Old 17-05-2013, 10:58   #151
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by Snowpetrel View Post
Does anybody know what sort of numbers of vessels it takes to start clogging the system up for the class B's?
Class A and Class B use two different channel allocation methods, but they both listen for an idle channel before transmitting. Class B gets whatever is left over, and if a slot is not available it just doesn't transmit. At sea, out of the range of coastal AIS base stations, this takes place autonomously. When in a harbor or otherwise in range of a base station, the Class-A channel assignment can also be managed by the base station. Class-B still gets the leftovers, if any. In addition, in the unlikely case of channel overcrowding, the base station can take other steps to reduce congestion.

I don't have the AIS channel capacity numbers in front of me, but the system has been designed so that Class-B will *never* interfere with Class-A vessels. A Class-B transponder can potentially block another Class-B transponder.

There are fringe cases where the channel allocation can break down, where vessels are at extreme range and can't hear each other. This is unlikely to cause an actual problem due to the F.M. "capture effect" where the strongest radio signal is the one that gets received.
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Old 17-05-2013, 11:00   #152
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Re: Please turn your AIS off when docked/moored/anchored

Just keep in mind that at one point, the US government was considering requiring that all boats, including presumably uncle Bubba's duck hunting boat, to have and use AIS transmitters. Imagine the confusion that would bring, especially on holiday weekends.
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Old 17-05-2013, 11:06   #153
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Re: Please turn your AIS off when docked/moored/anchored

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Suggest what you wish, Elliott.

You can be impressed by whatever you wish. Those are your standards.

I read what he said, and if that's the standard here, (and your comments, coming from a moderator seem to suggest that that is, indeed, the case) what I said stands-- I'm disappointed.

Have a nice day.
Jammer, I've been a member here long before I was a moderator, and I wrote that as a member. Forget that I'm a moderator, that's not the issue. Over the years I have had long and thoughtful discussions with Evans, here on CF and elsewhere, and I don't always agree with him, but I*am* impressed.

I stand by what I wrote.
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Old 17-05-2013, 11:47   #154
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Okay, I'm gonna try it once more using terms that may make more sense to the non-geeks:

Let us assume every boat has AIS and all are switched on from the moment they are first launched. They are switched off by Davy Jones only. There's the nightmare scenario for Evans.

Now let's see how we can deal with that. First we need the smart alarms that work on proximity in the future; let me explain that because many don't understand this: AIS transmits POS, SOG, COG and lots more for every mobile (we're called "mobiles" by the powers that be). When your AIS receives that info, it can calculate where each mobile is going to end up in 30 seconds, as well as where you will be in 30 seconds. Same for 1 minute, 2 minutes etc. this is kind of smart because it can eliminate mobiles that move away from you so that you're not bothered with them. A long time ago I used YachtAIS software which would display a radar-like screen with all mobiles around us and then it showed red areas from which I should steer clear to not put myself into the path of others in the future. Spiff.

Now we get to the point: mobiles that move vs mobiles that do not move. Evans would like mobiles that don't move to turn off their AIS. This way, they disappear from the system so that our AIS does not need to deal with them. The biggest flaw with this thinking is that these mobiles do not disappear in real life: they are still physically there. Who is to say they won't suddenly toss their lines and come out blazing at planing speeds?! in which case their AIS is still trying to get a GPS lock so can't transmit. Ouch! Or, another boat decides to leave but just forgets to turn the AIS on. Now we have a reversed ghost: does exist for real but not on the instruments. Ouch!

Back to the alarms: Evans states that there are too many and most are caused by mobiles that don't move. This is true and it is the reason why long time users of AIS like Mark and myself program the alarm to ignore these targets. This immediately stops all those annoying alarms, making it a non-issue. However, Evans states that this also suppresses alarms from stationary fishing boats or a ship that is hardly moving because it is waiting for something. That these mobiles are now excluded from alarms is true, but what Evans does not realize is that this is not an issue. The thing is that they don't move, meaning that the only way to collide with them is when you run into them. For this, eyeballs and/or radar are the required tools. NOBODY EVER SAID THAT AIS IS ALL YOU NEED! Prudent navigators use as many tools and methods as they can to improve safety.

You just don't run into other boats or ships, period.

Then there's another thing: not every mobile has AIS and some still have a receive-only system. More reverse ghosts! This in fact means, that your navigation methods besides AIS, will take care of mobiles without AIS, AS WELL AS for the mobiles for which an alarm was suppressed.

I hope this makes sense because it is.
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Old 17-05-2013, 12:48   #155
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by s/v Jedi View Post
Back to the alarms: Evans states that there are too many and most are caused by mobiles that don't move. This is true and it is the reason why long time users of AIS like Mark and myself program the alarm to ignore these targets. This immediately stops all those annoying alarms, making it a non-issue. However, Evans states that this also suppresses alarms from stationary fishing boats or a ship that is hardly moving because it is waiting for something. That these mobiles are now excluded from alarms is true, but what Evans does not realize is that this is not an issue. The thing is that they don't move, meaning that the only way to collide with them is when you run into them. For this, eyeballs and/or radar are the required tools. NOBODY EVER SAID THAT AIS IS ALL YOU NEED! Prudent navigators use as many tools and methods as they can to improve safety.

You just don't run into other boats or ships, period.

Then there's another thing: not every mobile has AIS and some still have a receive-only system. More reverse ghosts! This in fact means, that your navigation methods besides AIS, will take care of mobiles without AIS, AS WELL AS for the mobiles for which an alarm was suppressed.
Jeez, if the voices inside my head were a bit quieter, I may have been able to be that concise instead of making those points over very many posts...

Mark (back to being a reverse ghost - BOO!)
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Old 17-05-2013, 13:07   #156
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Re: Please turn your AIS off when docked/moored/anchored

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I know perfectly well how to 'cope'. I do it every day. BUT I also think that the behavior I am coping with is no longer appropriate and that my fellow seamen should consider changing. Its a behavior that no-one so far has offered a good reason for and which hurts the community.

I am not trying to give a good reason. I don't have many reasons to give and if I had a transponder, would have my unit powered down with the rest of the nav instruments when at a dock or at anchor. I would not have it on a separate switch, so it would be powered up when the nav instruments were powered.

What I am debating is that it "hurts the community". People have shown you the data that the system is designed for this capability, but you are still bothered by your alarms.

I do not view this community issue the same as plastic trash or talking on channel 16. Both of those are illegal by way of community agreement and consensual law enforcement. As are many other of the comparative issues raised in defense of the AIS argument. You will find others using the "community" issue to attempt to enforce mandatory life jackets and other things. This is a more applicable example to the debate here because these issues do not (yet) have community consensus that led to laws.

Several countries require AIS on all recreational vessels, and the US has considered this mandatory law. I suspect that it will eventually, and sadly, come to be. The type of reasoning for these systems to be mandatory could easily lead to mandating constant "on" (terrorist prevention and all that, you know). In this possible future, it will be irresponsible to tell people to turn off their AIS.



Since you don't even have a transmitter I can not see how you feel that I have attacked your character?

For others with transmitters, I have simply asked that they consider switching them off when docked or moored. I have simply stated, what is obviously true/factual, that they are polluting a public commons if they leave them on when docked/moored. I brought it up because they may not have considered that before.


I don't feel you have attacked my character. I was making a general point that your using words to the judgmental effect of "morality" and "clean wake" and all (and doubling down on them when challenged) amounted to ad hominem attacks on a debatable position (remember, neither yours or my positions are laws).

You did start out with a pleasant request, but fell off the edge into attacks when challenged.

You state your position as true and factual in the face of other data showing the opposite.
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Old 17-05-2013, 13:11   #157
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Re: Please turn your AIS off when docked/moored/anchored

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Several countries require AIS on all recreational vessels,
Which ones?
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Old 17-05-2013, 13:14   #158
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Re: Please turn your AIS off when docked/moored/anchored

I've just read this thread through; and, frankly, I feel surprised at how much resistance there is expressed here, for what seems like a request (not a demand) for a simple courtesy. One problem with extending the courtesy seems to be that it is *fun* for someone land based to use the internet to check up on his boat. Now, he's being asked to give up his fun. Suddenly a value judgment is called for: is AIS for an aid to navigation (as it were) an adjunct to a toy to show off? Someone offered possible tracking of a stolen vessel as a reason to leave it on, but given the relatively low number of thefts, I question its utility. We've never been unable to find a friend's boat at anchor without his using his AIS to tell us; that's what eyes are for, and really, all of know of our duty to avoid a collision. So far, what I have read are reasons that seem more ego-enhancing than aimed at being a responsible cruising sailor.

Perhaps few here other than Bash are familiar with the "tragedy of the commons", and should you be interested, try Googleing on it if you are interested in that bit of history. In a nutshell, it is a situation where selfishness leads to the loss of benefit for all.

It is having the data overload situation when there seems to be no need for it along with the emotional charge from the danger is what may have frustrated Evans, and indeed, has Jim & me, on occasion. DoJ, I think you're a little off center here, no one's demanding that others change--a fool's errand in any case--but that if someone introduces a subject as an issue, then some of the other guys might choose to alter the behavior of leaving the AIS on at anchor or when moored. If no one brings it up, then one disallows the chance of change. So if you'd like it discussed, an open issue as it were, you should bring it up.

And yes, I thought Evans sounded a bit rude in his 2nd and 3rd posts, but there was a lot of rudeness aimed at him, too. Some of you boys seem to like to get up and shout in each others' faces; I don't understand why. Others try to stick to facts. It seems that a lot of people don't express themselves kindly or objectively whether from aggravation, inattention, or just not caring how they treat others. Maybe there's an opportunity here to decide to be polite or kind!!
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Old 17-05-2013, 13:33   #159
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by s/v Jedi View Post
That these mobiles are now excluded from alarms is true, but what Evans does not realize is that this is not an issue. The thing is that they don't move, meaning that the only way to collide with them is when you run into them. For this, eyeballs and/or radar are the required tools. NOBODY EVER SAID THAT AIS IS ALL YOU NEED! Prudent navigators use as many tools and methods as they can to improve safety.
I fully agree that adding in a 'slow target' (say under .2kts) filter is the best (least worst) solution on board my vessel to reduce the collision alarms. . . . better than further reducing the CPA and TCPA screens.

However I would suggest you are wrong in the above, because most of the 'slow targets' I encounter are 'not always slow'. A boat picking pots may sit in a spot for a couple minutes but then zoom off. A ship burning time for a dock schedule or a pilot (or greenpeace blockading a vessel) will start moving again when the dock schedule (or pilot) says. So, I prefer to have an alarm that tells me that those boats are out there and generally possibly a hazard (like +- 1nm collision as the Vesper has it set).

And look, it should be obvious and you don't need to harp on it, that I don't depend solely on AIS to avoid collisions. In fact as I have said repeatedly, the reason I like alarms is that they draw my attention to the AIS when it has something to say, because otherwise I am normally looking at other stuff (the horizon, radar, etc). But there is some stuff that the AIS is excellent at (like 'see around corners') that none of that stuff does as well, and the alarm can bring it to my attention.

My understanding of the discussion is that some of you are taking the 'libertarian position' - eg I should not be suggesting how you should run your vessel. I reject pure libertarian positions when they harm a public commons. I think the community does in fact have some right to at least ask you to think about your impact on the commons. That is what I have done. I of course am not (and could not) demanding or requiring you change, just asking that you think about it. I think this is JUST LIKE talking on 16 or throwing plastic in the water, except its not illegal yet. As a note: I have actually talked to the USCG liaison officer about this topic and they agree with me from a vessel safety perspective but from a homeland security/tracking perspective they are not sure they may prefer to be able to see all boats all the time. . . . Well I care about vessel safety and don't much care about helping homeland security track things.

The only two reasons people have suggested they should leave they AIS on when docked are: (1) because its too much bother to turn off, or (2) they might then forget to turn it back on when they leave. Both of those seem to me to be really extremely weak excuses. Excuse me for being blunt again, but put a damn post it note near your wheel if you can't remember.

Anyway, some of you will be delighted to hear this is my last post on this.
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Old 17-05-2013, 13:34   #160
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Perhaps few here other than Bash are familiar with the "tragedy of the commons", and should you be interested, try Googleing on it if you are interested in that bit of history. In a nutshell, it is a situation where selfishness leads to the loss of benefit for all.
Respect for the commons is gone from most people's mind. Just try and sit somewhere fishing and count how many boaters zoom up on your location. They scare the fish away and after ten minutes decide there is no fish and go zoom up on the next boater and do the same.

We have gotten the attitude if no one else will respect the commons why should I compromise and respect them.
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Old 17-05-2013, 13:47   #161
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Originally Posted by estarzinger View Post

I fully agree that adding in a 'slow target' (say under .2kts) filter is the best (least worst) solution on board my vessel to reduce the collision alarms. . . . better than further reducing the CPA and TCPA screens.

However I would suggest you are wrong in the above, because most of the 'slow targets' I encounter are 'not always slow'. A boat picking pots may sit in a spot for a couple minutes but then zoom off. A ship burning time for a dock schedule or a pilot (or greenpeace blockading a vessel) will start moving again when the dock schedule (or pilot) says.
As soon as that pot picking boat zooms off, your AIS will alarm if he gets into a collision course with you. My last post was not complete, let me fix that: when a mobile for which alarms are suppressd for being stationary, speeds up again, the alarms for that mobile are immediately and automatically enabled again.

Try it, you will like it :thumbs:
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Old 17-05-2013, 13:48   #162
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Re: Please turn your AIS off when docked/moored/anchored

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I've just read this thread through; and, frankly, I feel surprised at how much resistance there is expressed here, for what seems like a request (not a demand) for a simple courtesy. .....................
If another person requested that AIS transmitters be left on, that would be confusing. Boaters wouldn't know which request to abide by.
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Old 17-05-2013, 13:50   #163
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Re: Please turn your AIS off when docked/moored/anchored

This request to prove that there is a good reason to leave AIS on is off point, in my opinion. I have argued the opposite side as Evans, but I have also stated that I do not have many good reasons for leaving it on and would not do so if I had one.

But again, I have argued that that is not the point, but a side show. The point is that the issue is here to stay and there are tactics to make it a non-issue. I have been stressed by unnecessary radar returns, but I would hardly expect that to go away. It is interesting that this is only an issue for people who have the ability to receive AIS, and it seems to be more prevalent in those who have only had AIS for a relatively short time.

Your data overload problem is NOT a problem of data availability. It is a problem that you are now seeing the data that you were not previously. This happens every time one acquires new detection systems - radar, scanning sonar, etc. My other life was intimately involved with moving into areas where data previously unseen were now flooding the gates. As anyone in particle physics, electronic design, communications and many, many other fields have experienced. The way to deal with it is NOT to ask it to go away, but to understand why it exists and develop tactics to live with it.

As AIS becomes more popular (or mandated), even actively navigated boats will be flooding your alarm systems to overload. There will easily be 50 targets within 1/4 mile of any boat in Newport harbor on a weekend. What then??? I am suggesting this is no different from the original complaint, only there is no solution that can be laid into these people's laps, like the original solution proposed.

I am very familiar with the "tragedy of the commons", but disagree that this parable applies in this situation. As with any parable, it is so easy to contort it to one's personal view and argue pedantically from that position. Ask Jesus...

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Old 17-05-2013, 13:58   #164
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Re: Please turn your AIS off when docked/moored/anchored

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Which ones?
I admit that I wrote that without hard facts. I was under the impression that Hong Kong, Singapore and a few other countries mandated AIS on all vessels - commercial and recreational. However, I made my statement without fact checking and withdraw it now.

Mark

edit: Singapore does require AIS on all vessels: New - AIS Requirement for Yachts Entering Singapore — Noonsite
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Old 17-05-2013, 14:03   #165
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Re: Please turn your AIS off when docked/moored/anchored

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If another person requested that AIS transmitters be left on, that would be confusing. Boaters wouldn't know which request to abide by.
I request that they be locked in a box with their on/off switch triggered by decay of a few atoms of U238. That way they would be both on and off simultaneously .

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