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Old 19-05-2013, 13:10   #346
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Re: Please turn your AIS off when docked/moored/anchored

OK Evans, I don't mean to press on you to turn off your alarms. You described the false alarms as interfering with a navigation situation. Your OP request was premised on this, and that premise carried a lot of weight because navigation is important.

Having lots of experience in the area you were in, I was confused as to how that happened given your description. Now I see that the alarms went off when you passed by the marina a couple of hours earlier with no navigational issues, but they were not present when you were faced with a situation. And in that situation, your AIS settings worked perfectly for you.

If your original post had stated that you passed by a large marina and your AIS rang all of the alarms because of docked units, and then made the point that this isn't really necessary and may clog things up (I still can't figure out that part), I think we all would have agreed with you.

Mine, and others disagreements were around how much of a navigational issue this situation is (and you did make that point). It turns out that it was not an issue, but that is not how you described it to us.

Enjoy the area, it is wonderful in the spring and fall and it looks like the weather will be improving up there soon.

Mark
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Old 19-05-2013, 14:19   #347
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Indeed, I do not agree that leaving transponders on degrades the system. The system is perfectly fine with it, that is my point. How many mobiles were transmitting while docked? 50? That is nothing; thousands of those can be handled by the system.

What it did degrade was the ability to safely navigate while alarms were ringing. -False- alarms were ringing. Those alarms are not part of the AIS system; they are locally generated on your boat by your gear. Also, the way you configure it changes the amount and types of alarms. You can program it so that it suppresses all those false alarms at the cost of not alarming for boats that are stationary and you are in danger of sailing into. Like stated, you can use other means for those low risk mobiles, especially since you need to keep a lookout watch anyway as their are mobiles without AIS out there too.

That is as simple as it is. Too simple actually, because I think you can even program the AIS which ignores stationary targets, to override that and sound alarm for any target that gets to a real close proximity. But not all units might support that. I won't think less of anybody who has an AIS unit that can't do that, nor even of those who don't have AIS at all. Or those who switch it off, or on, or shake it like samba balls to the tune of their favorite song.
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Old 19-05-2013, 14:48   #348
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Re: Please turn your AIS off when docked/moored/anchored

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Originally Posted by colemj View Post
OK Evans, I don't mean to press on you to turn off your alarms. You described the false alarms as interfering with a navigation situation. Your OP request was premised on this, and that premise carried a lot of weight because navigation is important.

Having lots of experience in the area you were in, I was confused as to how that happened given your description. Now I see that the alarms went off when you passed by the marina a couple of hours earlier with no navigational issues, but they were not present when you were faced with a situation. And in that situation, your AIS settings worked perfectly for you.

If your original post had stated that you passed by a large marina and your AIS rang all of the alarms because of docked units, and then made the point that this isn't really necessary and may clog things up (I still can't figure out that part), I think we all would have agreed with you.


OP #1 "I sailed by Newport this morning and had 53 collision warning alarms. 51 of them were docked/moored pleasure craft, while two were ships underway that were important for me to be able to follow."

Lots of editorials, flames, etc.. before Evans posted again at #86.

Mine, and others disagreements were around how much of a navigational issue this situation is (and you did make that point). It turns out that it was not an issue, but that is not how you described it to us.


Enjoy the area, it is wonderful in the spring and fall and it looks like the weather will be improving up there soon.


Mark
I will make a note that 51 unnecessary alarms should not be a "issue"....

Thanks teach....looking forward to running into you...
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Old 19-05-2013, 15:17   #349
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Re: Please turn your AIS off when docked/moored/anchored

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....looking forward to running into you...
I usually take actions to avoid being run into and don't appreciate boats trying to run me down .

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Old 19-05-2013, 15:29   #350
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Re: Please turn your AIS off when docked/moored/anchored

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I usually take actions to avoid being run into and don't appreciate boats trying to run me down .

Mark
Don't be alarmed...
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Old 19-05-2013, 17:25   #351
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Re: Please turn your AIS off when docked/moored/anchored

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How many people know you can send text messages with it?!
Had a young second third mate who found out he could use SMS facility with AIS, but not smart enough to delete the TX and RX files. I found out he was using it in much the same way as with mobile phone, and using it for social texting.
OK, I did not sack him, but I dont think he will ever do it again.

Thanks to all for the possible causes of the false AIS targets, what puzzled me was that I have only seen this in two places and on more than one occasion at each place. The false targets were not random, they stayed in the same position for some time . I know we passed Fraserburgh a number of times end of last year and early this year, and each time the false targets were present, and not just from one unit.
Went passed there twice last week, and no false targets, so its possible the Furuno upgrade might have resolved the problem.
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Old 19-05-2013, 18:45   #352
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Re: Please turn your AIS off when docked/moored/anchored

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Had a young second third mate who found out he could use SMS facility with AIS, but not smart enough to delete the TX and RX files. I found out he was using it in much the same way as with mobile phone, and using it for social texting.
OK, I did not sack him, but I dont think he will ever do it again.

Thanks to all for the possible causes of the false AIS targets, what puzzled me was that I have only seen this in two places and on more than one occasion at each place. The false targets were not random, they stayed in the same position for some time . I know we passed Fraserburgh a number of times end of last year and early this year, and each time the false targets were present, and not just from one unit.
Went passed there twice last week, and no false targets, so its possible the Furuno upgrade might have resolved the problem.
Yes, or like somebody else reported I think, an error with a shore D-GPS station, sending wrong correction data. But if that would go on for so long??

In the Amsterdam-IJmuiden Canal there is a place where a compass can start spinning like a gyro. It's been like that for 40 years and nobody cares enough to take care of it...
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Old 19-05-2013, 18:50   #353
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Re: Please turn your AIS off when docked/moored/anchored

There are periodic reports of observed GPS anomalies where positions are off by miles for a matter of minutes. I observed such a phenomena a long time ago when Selective Availability was still on, but this error was much greater than any normal wander--like a mile off. A bunch of us in the Abacos observed it, and one guy called around on the VHF all in a panic because his GPS-derived position didn't match what he was seeing on his radar. He asked us what to do, and I told him to look up ahead and from where he was he could see Marsh Harbour--it was a clear, sunny day.
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Old 19-05-2013, 19:07   #354
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Re: Please turn your AIS off when docked/moored/anchored

Don't have AIS but planning on fitting it sometime in the next couple of years. I understand it's needed for Singapore.

Ok, so I'll vote for turning off the AIS when docked. When moored I'd still favour turning it off but would turn it on if I thought any AIS equipped boat would come close. At anchor I'd favour having it on.

All those with it on must be connected to shore power. Me, not being connected, I like to keep every bit of power I have for the bilge pump.
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Old 19-05-2013, 21:16   #355
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Re: Please turn your AIS off when docked/moored/anchored

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How many people know you can send text messages with it?!
Class-A systems, yes. I am not aware of a Class-B transponder that will transmit text messages, although some of the display systems can show these messages. If someone knows of a Class-B with this capability, please let me know.

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All those with it on must be connected to shore power. Me, not being connected, I like to keep every bit of power I have for the bilge pump.
I occasionally leave my Class-B transponder on (gasp!!!). It draws 300 mA, or 7.2 Ah per day. My solar panels easily keep up with that.
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Old 19-05-2013, 21:59   #356
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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
Class-A systems, yes. I am not aware of a Class-B transponder that will transmit text messages, although some of the display systems can show these messages. If someone knows of a Class-B with this capability, please let me know.
It's not part of the specification for Class B and I'll bet is not even allowed on Class B sets. This facility was one of the reasons I initially was attracted to Class A, but then I started to think about whether anyone actually uses it, or whether it's like all the cool stuff you can do with DSC which no one even knows about, as basic as routine DSC calls.

I like to do my radio checks with routine DSC calls. The first time I called Falmouth Coast Guard with this, the OOW just about jumped out of his chair -- he evidently had never used this facility. They've gotten used to me by now (it's a much more efficient way to make a call on VHF). And DSC has been out now for how many years?
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Old 19-05-2013, 22:47   #357
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Re: Please turn your AIS off when docked/moored/anchored

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This thread is so messed up, I can hardly believe how few accidents happen. Well actually I do know: it is the professional mariners on the ships who roll their eyes again and again while saving the lives of the ignorant yachties on their kamikaze runs into harbour.
ROTFLMAO! Here's what professional mariners on ships are capable of--turning LEFT in front an oncoming supertanker.
http://gcaptain.com/intense-bridge-conversation-porter/
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Old 19-05-2013, 22:56   #358
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Re: Please turn your AIS off when docked/moored/anchored

I've missed most of the action on this thread because I've been out sailing, but when I installed my AIS transponder, it shared the power with the GPS, and both got turned off the few times I was in a marina. I also turned off my Vesper watchmate alarms in busy harbors when I had over 100 targets (mostly Class A)--the filtering software is not currently sufficiently developed to improve on the Mark I eyeball. However, it has the potential to be able to sort the priority targets--all it needs is a clever programmer.
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Old 19-05-2013, 23:26   #359
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Re: Please turn your AIS off when docked/moored/anchored

[I realize this is off-topic, but we probably have all the AIS tech-heads following this conversation, so I hope nobody minds.]

About AIS text-messaging:
Quote:
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It's not part of the specification for Class B and I'll bet is not even allowed on Class B sets.
That' what I was thinking. I've got the Class-B standards here, but was feeling lazy.
Quote:
This facility was one of the reasons I initially was attracted to Class A, but then I started to think about whether anyone actually uses it, or whether it's like all the cool stuff you can do with DSC which no one even knows about, as basic as routine DSC calls.
I had a strange encounter with a ship last summer (again, heading back to the mainland from Hawaii). A Russian freighter, just about on the horizon, turned around and started heading straight for me. I was starting to get *really* nervous when he hailed me on VHF using DSC calling, mentioned that he had seen my Class-B AIS signal (which is how he was able to call me using DSC), and asked if I would mind helping him see if his text messaging worked (more or less, there were some language difficulties). I thought he was talking about VHF DSC, so I said OK. At this point he was dead in the water a couple of miles off. Eventually I realized that he was trying AIS messaging, which I had no ability to receive, or send. Once we figured this out, he wished me a good day, headed east, and steamed off.

When I got home, having saved the raw AIS NMEA data on my passage, I wrote a message decoder program to see what he had sent me. It was basically something like "TEST MESSAGE DO YOU SEE THIS?".

Class-A AIS units can send addressed messages, much like a DSC-equipped radio can call a specific vessel using their MMSI number. Class-A AIS can also send general safety-related messages that all stations should be able to see.

Quote:
I like to do my radio checks with routine DSC calls. The first time I called Falmouth Coast Guard with this, the OOW just about jumped out of his chair -- he evidently had never used this facility. They've gotten used to me by now (it's a much more efficient way to make a call on VHF). And DSC has been out now for how many years?
I still barely know how to use my DSC VHF. I really ought to study it, but it sure hasn't caught on here on the West Coast, at least not among pleasure boaters.

I still wonder if that Russian freighter wasn't some sort of spy listening station.
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Old 20-05-2013, 01:01   #360
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Re: Please turn your AIS off when docked/moored/anchored

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It's not part of the specification for Class B and I'll bet is not even allowed on Class B sets. This facility was one of the reasons I initially was attracted to Class A, but then I started to think about whether anyone actually uses it, or whether it's like all the cool stuff you can do with DSC which no one even knows about, as basic as routine DSC calls.

I like to do my radio checks with routine DSC calls. The first time I called Falmouth Coast Guard with this, the OOW just about jumped out of his chair -- he evidently had never used this facility. They've gotten used to me by now (it's a much more efficient way to make a call on VHF). And DSC has been out now for how many years?

The SMS facility on Class AIS is used frequently for transmitting navigation warnings and safety alerts. I use it whenever we are towing, a nav warning is transmitted to all ships every 4 hours.

Agree about the DSC, should be used more often by everyone, one of the main objectives behind VHS DSC was to free up Ch 16.
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