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Old 18-05-2013, 10:34   #241
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Re: Please turn your AIS off when docked/moored/anchored

As Dockhead pointed out a few posts back, can we agree that both improved filtering technology and more awareness/courtesy on the part of boat owners can at least mitigate the problem? Seems like the point has been thoroughly made from both positions. Trouble is, they are not mutually exclusive. The system is primarily for collision avoidance while navigating/underway, and good points have been made that this also may have application for some anchored boats. Can this resolve the "debate" that ensued when a boater -- famous or not -- simply attempted to raise awareness of the issue and proposed a way to mitigate it??

Back to some add'l, hopefully relevant information, do those of you with Class B transponders know if they have the ability to transmit whether your boat is anchored or not? This seems to be common with Class A, but I couldn't remember if I've seen it on Class B. Thanks.
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Old 18-05-2013, 10:36   #242
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by colemj View Post
I am now tilting at windmills trying to keep this debate centered on the real issue.

Do you agree that the OP's "problem" goes away once and for all when every docked and moored (but not anchored, in your case, which differs for him) turn off their transponders?

Or are you simply reacting to the gut emotional level of "that seems like the right thing to do, shame on them", and going off into a side show issue?

Mark
I don't think Evans said that the problem would go away if people would switch off in their berths. I think he merely said that life would be made easier for other mariners if they would. Two very different things.
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Old 18-05-2013, 10:36   #243
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Originally Posted by Paul Elliott View Post

If you are referring to that "commons" argument, I suppose that depends on how you define "commons". If the OP thinks that those Class-B transponders were overloading the AIS timeslots, I can state with virtual certanty that this was not the case.

They may have been overloading his alarm "system", but that's not at all the same thing. That, I think, is the real crux of the problem.
Evans was opining that the class B units were overloading the time slots and his class B was skipping messages as you rightly described. That in itself is a "commons" argument. A moving boat's AIS signal may end up skipping time slots in favor of signals from docked boats thus reducing the update rate for the more important ones out in the channel.

The AIS system design is not perfect because it relies on the assumption that all class B units in a region can hear one another. For the class B units to skip time slots they have to be able to hear all the other class B units to know if there is a potential for overload. Boats in a marina are very likely not going to be able to hear as well as boats out on the main waterway. This is always a problem for TDM systems like AIS. It takes sophisticated back channels to sort it out when TDM is used in wireless systems. But there is no back channel with AIS.

I agree the system is designed to mitigate the problem but the problem is still there. I also agree that the alarm software is the most important problem. And the good news is it is fixable.
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Old 18-05-2013, 10:38   #244
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Re: Please turn your AIS off when docked/moored/anchored

Just realized my question may not have been clear. What I meant to ask is whether the Class B transponders can transmit the boat's status, i.e. underway (making way) vs. anchored/docked, i.e. not underway. Thanks again.
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Old 18-05-2013, 10:39   #245
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by Stu Jackson View Post
I'm still wondering why this approach seems to be such an issue. What's wrong with courtesy?
There is nothing wrong with courtesy. I am all for it and practice it as much as I can.

The problem with the "approach" is that lack courtesy was not the OP's actual problem. Well, maybe in his one specific and isolated case it was, but not in general, and he will continue to run into his "problem" well after all the courtesies have been met and fulfilled.

The "lack of courtesy" argument is an emotional appeal that seems to be hooking people and drawing their attention to its side show. It is not the OP's actual problem and no one is really even arguing it - some are just trotting it out whenever the real problem is discussed.

I'm not a great communicator - am I even writing intelligible English here???



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Old 18-05-2013, 10:44   #246
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by Dockhead View Post
I don't think Evans said that the problem would go away if people would switch off in their berths. I think he merely said that life would be made easier for other mariners if they would.
Ah, but it won't. That is the entire point. Yes, in his one specific case it would have been easier for him because he still seems new to the game.

Evans stated that it caused him a problem and certainly implied that it would not have been a problem had they been shut down.

Others have tried to show him that docked boats with AIS running was not his problem, all while agreeing that there was little reason for them to leave them running.

When recreational AIS is more widespread (this year!), the problem will not go away or be made any easier for other mariners EVEN WHEN ALL DOCKED, MOORED AND ANCHORED BOATS HAVE STOPPED TRANSMITTING!

Again, will there be any functional or practical difference between "only" 100 or 150 targets ringing alarms on your AIS? There will not.

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Old 18-05-2013, 10:44   #247
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by colemj View Post
On the contrary, I suspect that AIS was always intended for harbor control and tracking of commercial ships - similar to aircraft transponders. I could be wrong and will stand corrected if this was not the case.
I don't claim that this is authoritative, but here's what Wiki says:

"AIS was developed to avoid collisions among large vessels at sea that are not within range of shore-based systems." Automatic Identification System - Wikipedia, the free encyclopedia

I think its benefit for VTS is also pretty obvious, even if that was not the main idea behind AIS.

But collision avoidance in busy harbors, especially involving Class B vessels -- I don't think that was ever part of the brief, and I don't think AIS can even be useful there, as I've said.
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Old 18-05-2013, 10:48   #248
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by colemj View Post
I am going to be very presumptuous and attempt to get inside the OP's head.

..............

The OP then took his ball and went home because there was nothing he could do to make several of us stop seeing the underlying issues and their environments.

Mark
Mark,

I will respond to that post . . . I believe you are factually wrong on almost every point:

(1) you say that 'the problem is not docked boats but rather underway boats' . . . (a) I think you will find factually that +95% of pleasure craft are docked (or moored) at any given time. (b) I think you will find factually that underway vessels don't tend to all create collision alarms at the same time, so you can deal with them (mute them or do something else) one by one, unlike docked or moored boats. I was in the Solent with +150 active underway targets, and in Buzzards Bay with +180 active underway targets and neither cause me the same type of difficulty that docked or moored boats do. I have never needed additional filtering (beyond the Vesper pre-sets) for underway boats.

A second way you are wrong on this point is that the best filtering scheme for underway boats will be totally different than for docked boats. A low speed filter is the best solution for docked boats, but is obviously not useful for (most) underway boats. So they are two separate and independent problems, which can be solved/minimized in different ways. It's wrong to suggest that the solution for 'lots of underway boats' will also be the solution for 'lots of docked boats'.

(2) I am certainly not the oldest user of AIS around, but I have used both Class A and Class B units on different vessels from Cape Horn to London. I have experimented with various filtering, including low speed filters. I know how to use them. I know when to use them. Your implication that I am somehow completely ignorant or new to this is just wrong.

(3) The 'extra signals' generated by docked boats does in fact degrade the system. (a) Factually, sailing by NYC my system could only transmit in 1/2 of its scheduled slots, and Vesper's manual says 'this is common in very high traffic areas' (FYI Jedi's recommendation to me on this point was that I buy a Class A so I get priority slots over the class B). *** (b) Factually filtering does degrade the performance of the collision system . . . any filtering does. The less filtering that is necessary the better and the safer the system is. (C) we know Furuno and IMO have agreed that clutter can cause a problem. So it is factually wrong to say that unnecessarily leaving class B units on does not degrade the system. It degrades it both technically (blocked class B transmissions) and functionally (reduced anti-collision effectiveness).

(4) We as a community have a choice to make. We can force each other to put in low speed filtering because we are running AIS while docked/moored. Or we can turn our units off while docked and moored and not force that low speed filtering. Given that I have heard no compelling reason or benefit to running AIS while docked or moored, and I have heard compelling reasons to turn the units off, I think the community should encourage each other to turn our systems off. However it is wrong to suggest that I am asking for a law or regulation to that effect or that I am 'demanding' it. I just think we should consider the effect of our actions on others in the community of seamen (both pleasure and commercial). In this case I have previously said, and I have not heard any facts or logic that would refute, that those leaving their docked/moored units on are negatively effecting the community; and if they are doing that knowingly or intentionally I am led to the conclusion that they are acting selfishly. You say that someone in this thread has offered 'facts' that that is not true, but I can find no such facts, and I have had a long offline discussion with Jedi on this and he was able to provide no such facts (as I said above his closing recommendation to me was that I buy a Class A unit, as he has, so that I had priority over the class B's).

(5) An important part of the 'cruising community' for me is the 'community' spirit. The sense that, while ashore it is mostly 'every man for himself', in the cruising community we help and look out for each other. That if you have engine trouble I will be over with tools to help, even if I have never met you before, even if I have other things to do on my own boat. I consider that moral compass in the cruising community to be both important and valuable. I would hate to see it go away, and dragged back to 'every man for himself'. This is 'what's inside my head', rather than the ignorance you are suggesting.


*** Edit to Paul's point . . . I agree that I don't know who's or what signals were causing this specific problem. Factually it happened and Veper says it happens. It was the middle of the night so it was most probably NOT underway class B's. I discussed this with Vesper and my impression is that it was an aggregate AIS frequency noise level that was causing it. At the time one of the Vesper diagnosis screens was showing -80db noise while it is normally about -115db.
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Old 18-05-2013, 10:54   #249
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by colemj View Post
Ah, but it won't. That is the entire point. Yes, in his one specific case it would have been easier for him because he still seems new to the game.

When recreational AIS is more widespread (this year!), the problem will not go away or be made any easier for other mariners EVEN WHEN ALL DOCKED, MOORED AND ANCHORED BOATS HAVE STOPPED TRANSMITTING!

Again, will there be any functional or practical difference between "only" 100 or 150 targets ringing alarms on your AIS? There will not.

Mark
I don't really know -- why don't you ask Nigel, or another professional mariner? I think there might very well be a difference for someone between 100 targets, all at sea and of potential interest, and 150 targets, with 50 moored and irrelevant. Maybe won't prevent alarm overload, if you've got them configured when there are 150 vessels within AIS range, but might make it easier to select and look at a target of interest.

Although, again, by the time you've got 100 (or even 50) targets on the screen, maybe you shouldn't have your head in the AIS anyway, which I admit supports your argument.

But commercial mariners may not have any choice, and giving them even a slight break is already reason enough, I think, to switch it off.
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Old 18-05-2013, 11:07   #250
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Re: Please turn your AIS off when docked/moored/anchored

So I went sailing, and had a nice time navigating with the Mark I Eyeball, still in its original case.

While I have expanded my understanding on some fine points of AIS implementation and usage due to the issues discussed in this thread, I remain amazed at the debates that will stretch a thread out to nearly 20 pages.

It's almost like AIS was a new-style anchor or a shotgun in the quarterberth or something.
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Old 18-05-2013, 11:14   #251
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Re: Please turn your AIS off when docked/moored/anchored

Well, I did state I was being presumptuous...

I have agreed that there are few good reasons to leave it on while docked and have stated that I would not.

I stand corrected about your familiarity with AIS - you stated you had a new unit installed recently. However, I do not have the problems you are having and fail to see what the differences between our usage are. So I have to believe that I have developed tactics that work in your problem situation.

As for degrading the channels, my posts here have stated I do not have that information and have been asking about it. Others have stated that there is no problems and have explained why. While not "data" per se, they did provide reasoning.

Underway boats will be a problem in harbor situations in the near future - the same as the docked ones are now. Proximity alarms, etc will be ringing simply because of the close quarters and all of the random and numerous movements. Because you have not experienced it yet does not mean it won't or doesn't exist.

The Solent and Buzzards Bay are not harbors with docked boats. That is coastal cruising and will not cause the alarm problems you had in a harbor. Yes, a large number of boats are docked at all times, but that argument combined with your Solent and BB examples is a slight of hand to distract from the real problem of navigating when lots of vessels close to you have active AIS transponders. Look at the pictures I posted and tell me your alarms are not going to ring.

I fail to see the difference between 50 boats within a quarter mile or less of you moving slowly or stopped completely and randomly making course adjustments is going to require different filters than 50 stationary boats in a marina the same distance away. Well, I think it is easier to filter the marina, but we have disagreed completely on that point.

Again, your appeal to "community" and "spirit" and "moral compass" is emotional and clouds the real problem you are having and its underlying issues and environment. I consider myself deeply involved with the "community" and am the first to help out (I am heading over today to a boat I just met last night to help them with an alternator and network problems, and Michele jokes about how I am always jumping in the dinghy zooming toward any perceived need for help). But that has nothing to do with the points I have been making here. Because I disagree with you does not change my community standing, spirit or morality. I simply disagree with you and have been stating why as clearly as I can.

I still stand by what I wrote (above exceptions excluded), and still believe your problem is NOT docked boats. This problem is not going away and will manifest itself in active boats very soon.

Appealing to the moral community spirit of it all is very misguided and close to offensive if you intend to paint people with it who disagree with you on an unrelated issue.

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Old 18-05-2013, 11:16   #252
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by Dockhead View Post
But commercial mariners may not have any choice, and giving them even a slight break is already reason enough, I think, to switch it off.
Commercial mariners please speak up. Do class B boats transmitting in marinas give you navigation problems? Most marinas are so far removed from shipping channels that it would seem easy to filter based just on distance and speed.

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Old 18-05-2013, 11:27   #253
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Most marinas are so far removed from shipping channels that it would seem easy to filter based just on distance and speed.
40,000 boats docked in Ft. Lauderdale? From I have been reading, apparently the Class A folks just turn off the Class B alarms near harbors. Hopefully they remember to turn them back on when they go offshore.
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Old 18-05-2013, 11:29   #254
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Re: Please turn your AIS off when docked/moored/anchored

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do those of you with Class B transponders know if they have the ability to transmit whether your boat is anchored or not? This seems to be common with Class A, but I couldn't remember if I've seen it on Class B. Thanks.
Class-B does not transmit the "navigational status" information that Class-A provides. All anyone has to go on is the Class-B reported speed, and a speed of "0 knots" can obviously indicate many different situations.

For that matter, the Class-A navstat info is still occasionally incorrect, as this has to be edited by a crewmember. I still see "anchored" vessels steaming along at 17 kts. Not as often as I used to, but this will never be perfect as people will always make mistakes. I generally ignore navstat when I'm monitoring my AIS, and I would not want my alarms to depend on it.
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Old 18-05-2013, 11:29   #255
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
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I am going to be very presumptuous and attempt to get inside the OP's head.

I think the OP encountered a novel (for him) situation with his newish AIS unit and saw an easy and quick solution for his problem. He posted a seemingly innocuous and polite request for this solution to be implemented.

I was incorrect on his newish AIS; it still seems like this was a novel situation for him; his proposed solution did seem quick and easy and his original post seemed innocuous and polite

Others who have many years of experience operating with AIS in the situation the OP described attempted to help him. In doing so they questioned some of his newly acquired premises, and even provided some hard data in support.

Can't argue the correctness of this - the whole thread has been about it. However, as Evans pointed out, my characterization of "hard data" should have been "reasoned answers"

That raised his hackles and he and some others became a bit heated for a while. Instead of recognizing the actual underlying issues and environment that was causing them, the OP turned it toward emotional and gut-level arguments and appeals. No data were provided - just appeals to the "common good" and "courtesy", etc. These resonated with others and also blinded them to the real issues - which were completely outside of, and divorced from, "courtesy", etc.

The moderators got involved on the raised hackles and heat. The rest of it I stand by and do not agree that my characterization here is inaccurate.

It was pointed out that yes, people could be more courteous and aware, but that wasn't the OP's real issues and would never solve his actual problems.

Where is the incorrectness?

The OP then took his ball and went home because there was nothing he could do to make several of us stop seeing the underlying issues and their environments.

Glad to see you are still around

Mark
OK Evans, this is the post you said I was wrong on every point. I have to disagree with you (yes, I know I'm wrong on that also).

Mark
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