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Old 20-05-2013, 14:27   #451
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Re: Please turn your AIS off when docked/moored/anchored

Dave, I don't understand your point. We have one of your "poor" SH AIS receive units.

(a) It is connected to our chart plotter, computer and radar. All three are in our view at the helm.

(b) All have speed filters and alway show targets. I think the computer program will remove targets outside a set area, but it may only remove them until it gets a new transmission - I don't use this much, so don't know.

(c) For at least the computer, it shows a dynamic text listing along side the chart display, with the most "dangerous" boat listed first. If I click on any text listing, the target on the chart is highlighted and the vessel info appears on the chart next to it. If the target exceeds alarm parameters, both the text and the icon on the chart become red. If the target is WAY inside alarm parameters, it starts flashing.

Text listing is also possible on the chartplotter and radar, but I find its implementation obtrusive.

At all times, on all 3 systems, COG predictor lines are drawn for all targets as well as my ship. Set at 30 minutes, these predictor lines give a great visual on crossing situations.

So what makes our SH receive unit "poor", and how does any of this relate to transponders?

Mark
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Old 20-05-2013, 14:27   #452
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Re: Please turn your AIS off when docked/moored/anchored

Also Evans I wonder where you in an area where AIS class B was commanded to lower reporting levels. Hence your device might report them as missed slots.

Its also worth noting that class B can be commanded to report upto 5 sec intervals as well.
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Old 20-05-2013, 14:32   #453
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Re: Please turn your AIS off when docked/moored/anchored

I forgot to add that, while all that I listed sounds very complicated and cluttered with text, icons, predictor lines and such, it only takes a 1 second glance at a screen to completely understand the entire navigational environment around you, as well as its dynamics.

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Old 20-05-2013, 14:54   #454
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Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by goboatingnow View Post
Paul. I really think that the leisure market has been badly served by poor AIS receive only units , like the Standard Radio displays, and even the SIMrad and Vesper units. Heres why.

[...A really good analysis of desirable AIS human-interface features...]
From what I heard (and the little I've seen) the Vesper unit is probably the best of the bunch.

On my boat, I have numerous potential AIS displays:

At the helm, a Furuno chartplotter and a Standard Horizon VHF remote mic with AIS display capability (I feed it AIS data from my transponder).

Furuno: not horrible, but the chartplotter interface isn't really convenient for fine-tuning of alarms, or viewing of additional target information. It's possible, just not convenient. I use it to look at the target positions and vectors.

Standard Horizon VHF: The remote microphone AIS display is virtually useless for close-quarters AIS operation. I like having it for use as a simple, low-power proximity alarm when on the high seas.

Below at the navstation, I have another Furuno chartplotter, the VHF with it's tiny display, and a small computer running NavMonPc (the program I wrote). NavMonPc is the go-to AIS monitoring and alarm system. It's alarm features are less advanced than Vesper's, but the user-interface is still much more usable than the chartplotter or radio. There is room for improvement with all these systems.

The person using this gear needs to be realistic about what it can do. If all you want is a "there's a ship out there somewhere" alarm, then any of these gadgets will do the job. And that's a useful job, and perhaps all that someone wants. Higher levels of functionality with a workable user interface are definitely a work in progress. And at some point we will reach the limits of what can be done with the limited information available, especially given the range of unpredictable behavior we are faced with.

When in the harbor, I usually turn off my alarms. Vessels change course frequently, so even though NavMonPc ignores transient course changes, there's still no way I've found to have an alarm with any value.
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Old 20-05-2013, 14:55   #455
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by Paul Elliott View Post
[/I]

That's my take; in case of incorrect navstat. Or dragging anchor, I suppose.

Mark and Paul

I am 99% certain that internet AIS does not read the nav status, but instead makes an assumption, boat speed less than 0.3 kts and it assumes it is either anchored or moored.
I've just tested it, and that holds true. I'm at anchor off Aberdeen, looking at the Live Ship Map AIS site, out navstat is Anchored/Moored.
Setting our navstat to Restricted in Ability to Maneuver, and the our target on the web based AIS remains as Anchored/Moored.
Left it like that for 10 mins and watched the updates on the website, and no change in our status. Tried the same by setting status to Underway using engines, but the web AIS still indicates Anchored/Moored.
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Old 20-05-2013, 15:26   #456
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by goboatingnow View Post
(a) No AIS display should be invisible to the helmsmans, and if so should be turned off if it is ( alarms I mean) , cause 'down there ' its useless.

A practical challenge related to this point is that I am only very rarely at the helm. The boat is on autopilot/vane 99% of the time and I move around. So a screen fixed back at the helm is in fact not all that useful. (As a side note, in the Aegean incident they had a screen back at the helm, but the boat was on autopilot and no-one was back there looking at it. It could perhaps have prevented the incident if it had been placed at the front of the cockpit on in a portable tablet rather than fixed at the helm).

Another practical 'issue' is that my vessel is designed to be an extreme amp miser. For instance, I have a tiny plotter screen, which is often turned off. That is fundamental to the vessel system design and it's 'mission capability', which is to go long distances (like from cape horn to Tasmania non-stop) to very remote places in a totally self-reliant fashion (no extra fuel). We do not have a fridge nor a watermaker nor pressure water which mean that essentially our electrical system can be entirely turned off and we are still functional.

I am experimenting with an ipad this summer that can move around with me. It's useful, but the sunlight readability is very poor, so my next step will probably be to look for a similarily portable wifi tablet with a much better screen.

Obviously the best solution would be a heads-up display in my sunglasses. I have a tech working for me who could actually build such a thing, I think pretty easily . . . but some practical factors might crop up (like cost ).

(b) Class B filters should have a speed filters , but always show targets inside whereever proximity area is set. ( outside that they dont display). if the speed filter is exceed they show regardless.

Agreed. If a speed filter is set (which the Vesper can do) it would be good if the target is woken back up if you get 'close' to it (which I don't think the vesper can do, or at least I have not figured it out).

I dont think we need specific class B or A filters, more filters based on actions ( or lack of actions) by any craft.

I think more sophisticated filters than speed and cpa would be useful for me (and I have suggested several), but I guess I agree we don't "need" them (sort of like we don't "need" AIS at all).

Also Evans I wonder where you in an area where AIS class B was commanded to lower reporting levels. Hence your device might report them as missed slots.

Its also worth noting that class B can be commanded to report upto 5 sec intervals as well.

I am not sure, but don't think so. My manual says that the error I had was "Indicated that the last scheduled position report was not sent. It is normal to occasional miss position reports when operating in busy areas". That suggests to me it missed a scheduled position report, rather than having had the schedule changed, and I believe that was Vesper's thought also.

The manual says that a base station can command my unit into quiet mode, but that there will be an indictor of that on the status screen. I checked that and there was not. Edit: interesting that the manual says if a base station commands my unit into quiet mode that I can not override it and it is locked until the base station commands it back. I hope they whoever does not accidentally press that button and not realize it!

The manual does not talk about a base station being able to change the reporting frequency (Quiet mode is reporting totally off), so your comment is the first I have heard of that 'capability'.

I am curious what sort of authority/base station has the ability to direct my unit into quiet mode (or different reporting frequency)? Does anyone know in practice who can do that? I guess I would be a bit surprised if the local USCG had that capability because they seem way way behind the times on AIS. I could image vessel traffic control having that sort of equipment/capability. I guess I would have been right at the very extreme range of any traffic control equipment.
.............
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Old 20-05-2013, 15:41   #457
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Dave, I don't understand your point. We have one of your "poor" SH AIS receive units.

(a) It is connected to our chart plotter, computer and radar. All three are in our view at the helm.

(b) All have speed filters and alway show targets. I think the computer program will remove targets outside a set area, but it may only remove them until it gets a new transmission - I don't use this much, so don't know.

(c) For at least the computer, it shows a dynamic text listing along side the chart display, with the most "dangerous" boat listed first. If I click on any text listing, the target on the chart is highlighted and the vessel info appears on the chart next to it. If the target exceeds alarm parameters, both the text and the icon on the chart become red. If the target is WAY inside alarm parameters, it starts flashing.

Text listing is also possible on the chartplotter and radar, but I find its implementation obtrusive.

At all times, on all 3 systems, COG predictor lines are drawn for all targets as well as my ship. Set at 30 minutes, these predictor lines give a great visual on crossing situations.

So what makes our SH receive unit "poor", and how does any of this relate to transponders?

Mark
Sorry slightly poor English. I really ment relying on these tiny displays like on the SH or icom units. Not that the unit itself was poor , SH makes really great kit.
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Old 20-05-2013, 15:51   #458
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by estarzinger View Post
I am curious what sort of authority/base station has the ability to direct my unit into quiet mode (or different reporting frequency)? Does anyone know in practice who can do that? I guess I would be a bit surprised if the local USCG had that capability because they seem way way behind the times on AIS. I could image vessel traffic control having that sort of equipment/capability. I guess I would have been right at the very extreme range of any traffic control equipment.
Evans,

Looks like the USCG can (and has) done just this, although it appears to have been done inadvertently.
Attached Files
File Type: pdf USCG_Safety_Alert_07_10_Excerpts.pdf.pdf (306.4 KB, 25 views)
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Old 20-05-2013, 15:55   #459
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Re: Please turn your AIS off when docked/moored/anchored

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Mark and Paul

I am 99% certain that internet AIS does not read the nav status, but instead makes an assumption, boat speed less than 0.3 kts and it assumes it is either anchored or moored.
I've just tested it, and that holds true. I'm at anchor off Aberdeen, looking at the Live Ship Map AIS site, out navstat is Anchored/Moored.
Setting our navstat to Restricted in Ability to Maneuver, and the our target on the web based AIS remains as Anchored/Moored.
Left it like that for 10 mins and watched the updates on the website, and no change in our status. Tried the same by setting status to Underway using engines, but the web AIS still indicates Anchored/Moored.
You are probably right, internet AIS sites such as Marinetraffic.com don't pass along navstat. Or they might, I'm not sure.

But I'm not using that. Because I share my raw NMEA AIS data with several other organizations, or just because I asked nicely, I have access to quite a bit of NMEA data via TCP/IP. This is effectively the serial data stream as sent from a receiver or transponder to your chartplotter. Since the data is coming from multiple receivers there is some de-duplication filtering going on, but otherwise I get the exact same bits that you would see on your boat.
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Old 20-05-2013, 16:19   #460
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Evans,

Looks like the USCG can (and has) done just this, although it appears to have been done inadvertently.
Here's the full extent of class control

2.1.2.2 Assigned mode
An “assigned” mode for operation in an area subject to a competent authority responsible for traffic monitoring such that:
– the reporting interval, silent mode and/or transceiver behaviour may be set remotely by that authority using group assignment by Message 23; or
– time periods are reserved by Message 20 (see § 3.18, Annex 8).
2.1.2.3 Interrogationmode
A “polling” or controlled mode where the Class B “CS” AIS responds to interrogations for Messages 18 and 24 from a Class A AIS or a base station. A base station interrogation for Message 19 specifying transmission offset should also be answered4. An interrogation overrides a silent period defined by Message 23 (see § 3.21, Annex 8).
A Class B “CS” AIS should not interrogate other stations.

The reporting interval can be changed

Full tech spec http://www.itu.int/dms_pubrec/itu-r/...4-I!!PDF-E.pdf

I presume most people don't realise AIS is controlled by DSC messaging on ch 70 ! ( well I know this is an optional to TDMA telecommands

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Old 20-05-2013, 16:26   #461
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Re: Please turn your AIS off when docked/moored/anchored

When I see a class-B but the name doesn't show up (which is only transmitted now and then it seems), I interrogate that unit to get the boat name and other info that is missing. This works very well. I never realized that this was a class-A feature as well.

Just for fun another screen shot where I did get an alarm (check the red area):
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Old 20-05-2013, 16:31   #462
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by goboatingnow View Post
Here's the full extent of class control

Full tech spec http://www.itu.int/dms_pubrec/itu-r/...4-I!!PDF-E.pdf

I presume most people don't realise AIS is controlled by DSC messaging on ch 70 !

Dave
Thanks, interesting. I had no idea they could control it in all those ways. I now vaguely remember reading the notice, that Nigel liked to above, but at the time I thought it was a class A only thing.

I presume if/when they do that (intentionally rather than by accident), that it would not be secret and that I would also get a safety or nav message, which I did not.
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Old 20-05-2013, 16:33   #463
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Re: Please turn your AIS off when docked/moored/anchored

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A practical challenge related to this point is that I am only very rarely at the helm. The boat is on autopilot/vane 99% of the time and I move around. So a screen fixed back at the helm is in fact not all that useful.
But one would suppose that in close confined waters or areas of lots of boat traffic, where this thread has been concerned, one would be mostly at or near the helm? In open water navigation, you would not have the alarm problem.

We have a Panasonic Toughbook remote display that is very readable in direct sunlight, weatherproof and is used to control our below deck charting computer. Battery life is 8-10 hrs, so not as good as the iPad, but presumably you would only need it in certain situations for relatively short times.

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Old 20-05-2013, 16:34   #464
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Re: Please turn your AIS off when docked/moored/anchored

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I presume if/when they do that (intentionally rather than by accident), that it would not be secret and that I would also get a safety or nav message, which I did not.
That's the point, only class-A units get those...
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Old 20-05-2013, 16:39   #465
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Re: Please turn your AIS off when docked/moored/anchored

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But one would suppose that in close confined waters or areas of lots of boat traffic, where this thread has been concerned, one would be mostly at or near the helm?
One would suppose wrongly

I have a wireless remote for the autopilot. I can change course, or even 'directly hand steer' from anywhere.

I would most often be near the front end of the cockpit where the mainsail sheet is, and I do have a remote vhf mic plugged in there also. But I could really be anywhere - from the helm to the bow (say freeing the anchor).
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