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Old 20-05-2013, 18:03   #481
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Originally Posted by s/v Jedi View Post

Kidding aside, mine is a development (pre) version of the SR261. With programmer to change software etc. I spent 4 months with these guys to get all the bugs out and test it in real conditions, until it worked. There were some AIS anomalies around the ABC's during those months

Also, right after that, I worked with Y-tronics to support the SmartRadio transponders in their Yacht-AIS software. This is why it can program all the static data incl. class-A for SmartRadio, send/receive messages etc. It's a shame he discontinued selling the software.
Yes nick , but it em ,never passed any real certification ahem ahem.

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Old 20-05-2013, 18:27   #482
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Re: Please turn your AIS off when docked/moored/anchored

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Yes nick , but it em ,never passed any real certification ahem ahem.

Dave
Of course not, it's only possible to certify something after it's development is completed and can be offered for the certification process. The 261 was never even offered for certification because by the time we were ready with the software, other hardware models were ready. I don't think the 261 was ever seriously sold; I know of 4 others that I visited to update their software. The same software was running on the systems that got certified; just some module initialization was different as the hardware changed a bit.

I'm pretty sure the software is still mostly the same in the current units. These routines are all pretty involved and timing critical. We had to convert parts to assembly to get it right.

Not much of my gear is dumbed down to certification levels.. my VHF is another good example TM-D710a plus mods 50W
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Old 20-05-2013, 19:13   #483
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by Kettlewell View Post
The thing is Evans was sailing by Newport and picking up all the AIS signals from all the boats in the harbor--if he set the alarm circle too tight he wouldn't pick up the commercial vessels underway out where he was. This is a result of all the superyachts tied up in Newport these days--I have been next to some of these guys who leave their radars on while tied up at the dock in harbor.

Read your manual; set your alarm by speed and hazzard. Set the filters as necessary to reduce nusance alarms. I use my AIS Watchmate as an anchor alarm on the hook. At the dock, I can turn it off. I bought it so I would be seen. If your AIS has no filters - sorry. You won't find the big guys turning theirs off either. As I recall, once you have one, you are generally required to use it.
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Old 20-05-2013, 21:12   #484
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Re: Please turn your AIS off when docked/moored/anchored

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(Why is that so difficult to accept?)
Because of the way he went about it.
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Old 20-05-2013, 21:52   #485
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Re: Please turn your AIS off when docked/moored/anchored

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Also need to add the ship data feilds every 6 mins. They take an additional 2 slots. All class b even stationary ones still try to transmit these as. I understand it. So a moving class b uses 14 slots every 6 mins and a stationary uses 4 every 6 mins.
Yes, I did mention the static messages in a post several pages back. Both Class-B and Class-A send (or at least try to send) the static ship's data once every six minutes, regardless of speed or navstat. The static messages consume two timeslots, so this does effectively double the channel-usage of the docked Class-B vessel, to 0.66 slots per minute. Still quite low. Of course if you have enough Class-B boats it does add up. I suppose that's one of the issues we are discussing.
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Old 20-05-2013, 22:50   #486
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by Nicholson58 View Post
As I recall, once you have one, you are generally required to use it.
The USCG requires continuous operation at all times the vessel is underway, at anchor, or moored "in or near" a commercial channel or shipping fairway, except in instances where such operation compromises the safety of the vessel.

I've been presuming that this regulation applies to vessels required to use AIS, not to recreational vessels <65'.

Warships exempted, of course.
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Old 21-05-2013, 02:00   #487
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Re: Please turn your AIS off when docked/moored/anchored

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....

AIS is a technical protocol for collision avoidance, there is no "commons" argument. The 'commons' in this case is more then large enough to handle the 'bulls' ( class A) that it was designed for. The sheep ( class'b') eating in the corner have no rights, you can hardly ask one herder to take his away so that your sheep can have more grass!!

Dont drag the debate into absolutes.

dave
That's a rather poor analogy, it seems to me.

Firstly the OP had nothing to do with rights, it was about refraining from squandering a limited resource.

The boats tied to a dock while transmitting are not "Eating" grass: that implies they're deriving utility.

I think it would have been closer if you had said they're sleeping on the grass, denying other sheep sustenance of which they are in immediate need, when there are equally satisfactory places to sleep, which are not grassed. They're not even 'reserving' the grass for their own future use.

----

Surely formal "rights" do not need to be invoked to deal with situations like this.

It seems simple enough: you assess the benefits derived from the behaviour, multiplied by the number of beneficiaries. In cases like the docked boats, the benefits are infinitesimal while the denied benefits are significant.

It gets murkier if people are using Class B AIS to derive personal benefits for which it was not intended: eg as a sort of techno-night watchman.

My personal view is that such users should be vigilant that they are not in localities where this would be likely to impair the operation of AIS for the intended purpose, and find a more appropriate method which does not result in 'denial of service' to others if this is happening.
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Old 21-05-2013, 02:16   #488
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Re: Please turn your AIS off when docked/moored/anchored

I think, furthermore, that "rights" are neither a necessary nor a sufficient remedy when it comes to misuse of a commons.


A more realistic example involves the air, which (along with water) is a fundamental, universal commons.

If someone insists on leaving their engine running needlessly in an enclosed space, denying people in that space the oxygen they need to breathe, I don't think it's necessary or helpful to invoke 'rights' - I'm not even sure there are any formal rights, in most jurisdictions.

Those who need air do not need to claim a right, and as for the person running their engine, they'd have to be remarkably bloody-minded to claim a right, even on the www.

The whole point about sharing a commons is that it relies on the goodwill of individuals to monitor their contributions and their deductions, and keep them in balance.

It's not practicable to formally administer a commons: it's an organic, civil-society function.

The classic Tragedy scenario typically starts when individuals reason that the supply is plentiful in comparison with their needs, therefore no self-rationing is required.

They fall into the trap of dividing what they personally extract from the commons by the total number of users, and finding it trivial.

This is like Alicia & Bern reasoning that inflating an insurance claim is not a problem because they are small, and the company is big.

The reason the company is big is because it is exposed to claims from LOTS of small people like them.

To claim a special dispensation to a disproportionate benefit, not available to others without collapsing the house, is something few people would care to explicitly justify in public, if they thought about it in these terms.

It's not peculiarly a moral question in the usual sense; it's about whether the rate at which goodwill is applied and replenished is sufficient for civil society to continue to function ... at least, that's how it seems to me.
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Old 21-05-2013, 02:26   #489
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Yes, I did mention the static messages in a post several pages back. Both Class-B and Class-A send (or at least try to send) the static ship's data once every six minutes, regardless of speed or navstat. The static messages consume two timeslots, so this does effectively double the channel-usage of the docked Class-B vessel, to 0.66 slots per minute. Still quite low. Of course if you have enough Class-B boats it does add up. I suppose that's one of the issues we are discussing.
Given the number of slots available docked vessels take up a tiny bandwidth. It's unlikely they are any sort of significant loading on the AIS bandwidth even in quite large numbers

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Old 21-05-2013, 04:46   #490
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Re: Please turn your AIS off when docked/moored/anchored

Jut a comment on 'alarms'. I understand a few of you don't have much use for them. However, it's pretty well documented that they add safety. Humans lose focus and their attention wanders. This can and does happen anytime, but especially at about 2am, especially 'short handed', especially at about the second night at sea. Alarms are a way to bring the attention back to something that needs it.

General "best practice" (in fields outside of yachting) would definitely have ETA alarms (to important planned events, like arrival at a significant turning point) and special alarms (like for AIS/radar potential collisions, or engine overheat). And those alarms should be loud enough to be heard over the likely highest 'normal' ambient noise level (like perhaps the engine running, and sound system on, on on a yacht) in all areas where the watch might be (cockpit, nav station, head, engine room).

That's the conclusion from the several accident investigations I have been involved in, and from professional experiences in commercial/military applications.

Just as a very specific recent example, any of a number of the 'best practice' alarms would have saved the Aegean (either one of several ETA alarms or a collision alarm).

Now, I am, of course, not trying to suggest any of you should change your operating practices regarding alarms . I am just suggesting there is a reason I use them, the way I do.

And before someone else says it . . . of course you should not "depend" on alarms, they are just a help. . . . . but they have proven to be a help.
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Old 21-05-2013, 05:01   #491
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Re: Please turn your AIS off when docked/moored/anchored

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Jut a comment on 'alarms'. I understand a few of you don't have much use for them. However, it's pretty well documented that they add safety. Humans lose focus and their attention wanders. This can and does happen anytime, but especially at about 2am, especially at about the second night at sea. Alarms are a way to bring the attention back to something that needs it.

General "best practice" (in fields outside of yachting) would definitely have ETA alarms (to important planned events) and special alarms (like for AIS/radar potential collisions, or engine overheat). And those alarms should be loud enough to be heard over the likely highest 'normal' ambient noise level (like perhaps the engine running, and sound system on, on on a yacht) in all areas where the watch might be (cockpit, nav station, head, engine room).

That's the conclusion from the several accident investigations I have been involved in, and from professional experiences in commercial/military applications.

Just as a very specific recent example, any of a number of the 'best practice' alarms would have saved the Aegean (either one of several ETA alarms or a collision alarm).

Now, I am, of course, not trying to suggest any of you should change your operating practices regarding alarms . I am just suggesting there is a reason I use them, the way I do.
I don't think anyone has advocated against alarms generally.

I personally think alarms do more harm than good in environments where most alarms will necessarily be false. It's a distraction, which is harmful to sit awareness. Thus I would never set a shallow water alarm when I'm knowingly venturing into skinny water -- my eye will be on the sounder the whole time anyway, and I don't need the distraction.

Likewise, I would never set an AIS alarm (or MARPA) in a busy harbor -- anyway, I will have my head on a swivel watching the traffic, and here COLREGS rule. More importantly, an AIS alarm is valuable really only when you're on a steady course, and your targets are on steady courses -- i.e., out at sea. In a harbor where most boats are being hand steered, are following channels, are maneuvering, so that their courses are always changing, AIS in general will really not give you any useful information, much less the alarms, which will be going off all the time for no reason as vessels' projected tracks cross yours as they maneuver.

I only recently installed my first AIS set, so I'm still working out the best way to use it, and don't claim to be an expert, but so far I have been just switching it off in busy harbors (I don't think transmitting does anyone any good, either, in those conditions).

AIS did recently perform a useful function for in the Solent, however, when it notified me of a freighter bearing down on me from behind, as I was passing SW towards the Needles. I might not have otherwise noticed him, which would have required him to maneuver around me, which is not good in the relatively confined waters of the Western Solent. As it was, I was able to make a (visible, noticeable, since it was contrary to the COLREGS) maneuver to starboard, in time to let him get by me without altering his course. So here's a good case, I guess, of where AIS is beneficial even in relatively restricted waters, but I did not need any alarm for that.

Out at sea, especially crossing shipping lanes, alarms are extremely valuable. I used them before on MARPA and will use them with AIS. Crossing the Channel you might have to track up to 4 or 5 ships at once -- something I used to do with notepad and hand bearing compass, which can be really overwhelming. If you have alarms set, you can concentrate on that ship which is the immediate danger and know that the system will tell you if you start to get into a situation with another -- a tremenous advantage.

And, as Evans says, of course it greatly enhances watchkeeping at sea if you get an early warning from the system if a ship appears on a dangerous course. Out at sea in the shipping lanes, a big container ship booking down the Channel at 20 knots, can go from barely visible to you on deck to really dangerous (you don't know which way to turn to avoid) in a shockingly short period of time. The watchkeepers need all the help they can get in such situations. Especially if you are busy watching some other ship, it is extremely easy not to notice a situation like that until it is too late to avoid a really dangerous situation.
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Old 21-05-2013, 05:06   #492
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Re: Please turn your AIS off when docked/moored/anchored

^^

With what I called the 'special alarms', the trick is obviously to set them so as to balance false positives against false negatives. From your post, I would (most humbly) suggest you have error toward the extremes . . . to many false positives when you have set an alarm, and too many false negatives when you turned them entirely off. The trick/skill is to be somewhere in between there.

"but I did not need any alarm for that."

Yes, you were paying attention. That's terrific, obviously what is best.

But, humans do lose focus and do became distracted and do lose their attention. Some humans quicker than others, but it happens to everyone. The point of alarms is to 'safety net' that (common) point of failure.
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Old 21-05-2013, 06:17   #493
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Re: Please turn your AIS off when docked/moored/anchored

I have mentioned that I prefer turning off audio alarms in harbor and other close situations. What I wasn't clear on is that I still have alarms - just not audio.

In another post, I described how I am presented with vessels turning red and flashing when crossing alarm territory, as well as a dynamically updating text list showing the most "dangerous" vessels first (also in red text). These visual alarms alert me to the situation and are easy to "turn off" in my head without further ado.

Humans also lose focus when barraged with continual alarming noise - heck, the military and CIA uses this technique.

And audio alarms are set on our boat for more open passages where ships are on steadier courses and speeds - particularly at night.

Evans has described his not being continually present before a visual display in these circumstances, but one does not need to be glued to a display - one only needs occasional glances at this type of display to understand and stay abreast of the situation.

For me, Evans example of 50 non-critical audio alarms going off and needing to be shut down one by one is more distracting and potentially dangerous than not having any audio alarms at all.

And a specific question on acknowledging and quieting an audio alarm for a vessel on the Vespar in use here - doesn't that vessel retrigger the alarm the next time it transmits or your vessel moves relative to it? If so, then I really find audio alarms in these situations more of a distraction than safety device (I could even be persuaded to argue that audio alarms are unsafe here).

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Old 21-05-2013, 07:12   #494
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by estarzinger View Post
^^

With what I called the 'special alarms', the trick is obviously to set them so as to balance false positives against false negatives. From your post, I would (most humbly) suggest you have error toward the extremes . . . to many false positives when you have set an alarm, and too many false negatives when you turned them entirely off. The trick/skill is to be somewhere in between there.

"but I did not need any alarm for that."

Yes, you were paying attention. That's terrific, obviously what is best.

But, humans do lose focus and do became distracted and do lose their attention. Some humans quicker than others, but it happens to everyone. The point of alarms is to 'safety net' that (common) point of failure.
Of course, but you really have no choice but to pay attention when you're sailing in busy waters like the Solent. The most perfect alarm system in the world is no substitute at all for continuous vigilance, and will really not make up for any serious lapse in attention, when you're sailing someplace like that.

Out at sea, it's very different. Nobody scans the horizon continuously out at sea (I even had crewmen, veterans of long bluewater passages, who liked to read books on watch -- a practice I forbade). Here the safety net analogy becomes really apt, and alarms were really made for this situation.

Like I said, I don't expect any useful information from AIS when vessels around are maneuvering. The system doesn't know whether targets are following channels, and doesn't know when that turn is going to stop, and therefore can't produce any meaningful warnings, as far as I can figure out.

That seems like a fairly obvious point to me, but again -- I am pretty green AIS user and still haven't worked out the best way to use it, so I might be talking out my stern. I'm certainly not trying to impose my way of using it on anyone else, and far be it from me to argue that someone else's way of using it is wrong. I don't know yet.
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Old 21-05-2013, 07:21   #495
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pirate Re: Please turn your AIS off when docked/moored/anchored

[QUOTE=colemj;1240656 I really find audio alarms in these situations more of a distraction than safety device (I could even be persuaded to argue that audio alarms are unsafe here).

Mark[/QUOTE]

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