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Old 07-07-2015, 06:06   #31
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Re: Live AIS Via Internet

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Originally Posted by MarkJ View Post
His88

What you dont seem to understand is that internet AIS is not current.

Its not uptodate.

Its old information

Its not new


I just took this screenshot, attached, of my boats internet AIS that I have on my website. Please have a look at the Time of Last Report.

Did you read it? How long ago was it?

This time delay is normal. If it were not normal I would be in a deadset panic that my equipment has failed.

So what earthly use is it except to know in a very general term that my boat WAS somewhere some time ago.

Want to see if I just lied to you? Check it "live" Our Life At Sea - World wide Ship Positions AIS Location

Mark
Since there is a time stamp, it should be pretty easy to highlight old data.
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Old 07-07-2015, 06:11   #32
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Re: Live AIS Via Internet

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Originally Posted by valhalla360 View Post
...of course when I see the little boat icon driving down the beach, I am smart enough to realize the GPS and chart datum aren't lining up and make adjustments to account for it...
After adjusting your charts, you might get the rude awakening that it actually was someone running Boat Beacon on his phone while driving his SUV along the beach. Now you've screwed up your chart calibration because you made an incorrect assumption that the icon on the beach was actually a boat.

There are a lot of potential dangers to using crowdsourced data for navigation.
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Old 07-07-2015, 06:22   #33
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Live AIS Via Internet

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Originally Posted by valhalla360 View Post
If you have no concept of using multiple sources of data to confirm and provide an overall view of what is going on, you would be correct. If you use a modest dose of common sense, old data is not bad data.

No doubt a full transciever would be best but they are expensive, they require an installaiton and require a power supply. We may get there at some point but we aren't there, so this would be a simple alternative to provide an improvement over no data.

This is like saying you shouldn't use electronic charting because they might be out of date...of course when I see the little boat icon driving down the beach, I am smart enough to realize the GPS and chart datum aren't lining up and make adjustments to account for it. To go back to paper charts or worse no charts in congested complicated areas is not a better option.
Just download the marine traffic app and use that when you want to see what is around you and where they were a few minutes or more ago. No need to mix inaccurate data with your navigation software

Click image for larger version

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Views:	118
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ID:	104826

The simple REAL alternative to an AIS transceiver is a cheap AIS receiver and an antennae on the pushpit

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Old 07-07-2015, 06:42   #34
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Re: Live AIS Via Internet

This 59m super yacht was last reported on marine traffic doing 16.4 knots 5 minutes ago (and counting)

This means it is possibly 1.36nm from that position. In the 5 minutes since the report it could have changed its course.

As it is a class A transponder on board, all boats within range will have gotten position updates every fey seconds. If it was a speed boat with a class B, then the position updates will have been sent every 30 seconds.

Click image for larger version

Name:	ImageUploadedByCruisers Sailing Forum1436272324.914535.jpg
Views:	80
Size:	120.7 KB
ID:	104828

Sure, in a connected world it would be nice to have the internet AIS positions, but only for vessels beyond your AIS receiver range where 5 or 10 minutes between reports doesn't matter.

Internet AIS should not be used on the water, unless you are trying to find MarkJ because he owes you a beer





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Old 07-07-2015, 07:09   #35
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Re: Live AIS Via Internet

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Originally Posted by valhalla360 View Post
If you use a modest dose of common sense, old data is not bad data.
I've tried real AIS along side the google earth plug in with marine traffic on opencpn. Some ships had a mile between the real position and the internet position.
I prefer not to bother with old data. Maybe in areas with next to no traffic, but after playing with both systems side by side in a high traffic area, there is a strong argument to say that internet ais is actually worse than none. We are so used to computers spitting out exact info, knowing the data might be bad isn't enough, there's a very strong instinct to believe it's all real. We ain't as clever as we like to think we are all the time.
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Old 07-07-2015, 07:38   #36
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Re: Live AIS Via Internet

The Chinese foresaw this predicament centuries ago.

"Man with one watch always know what time it is. Man with 2 watches never know what time it is."
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Old 07-07-2015, 07:45   #37
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Re: Live AIS Via Internet

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Originally Posted by valhalla360 View Post
.... If you use a modest dose of common sense, old data is not bad data.
How would you use old data for navigation?

Or is your intended usage for some other reason?
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Old 07-07-2015, 08:25   #38
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Re: Live AIS Via Internet

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Originally Posted by RhythmDoctor View Post
After adjusting your charts, you might get the rude awakening that it actually was someone running Boat Beacon on his phone while driving his SUV along the beach. Now you've screwed up your chart calibration because you made an incorrect assumption that the icon on the beach was actually a boat.

There are a lot of potential dangers to using crowdsourced data for navigation.
I wasn't talking about modifying the chart datum but taking note and making a mental adjustement.

I think I would know if I was driving an SUV along the beach. I was talking about charts that are just off a bit and show you running along the beach.
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Old 07-07-2015, 08:27   #39
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Re: Live AIS Via Internet

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Originally Posted by hoppy View Post
Just download the marine traffic app and use that when you want to see what is around you and where they were a few minutes or more ago. No need to mix inaccurate data with your navigation software

Attachment 104826

The simple REAL alternative to an AIS transceiver is a cheap AIS receiver and an antennae on the pushpit

Sent from my iPhone using Cruisers Sailing Forum
I'd rather have it all in one place and not have to flip back and forth between applications.

By this logic, you should run a dedicated AIS completely independent of your chart plotter.
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Old 07-07-2015, 08:28   #40
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Re: Live AIS Via Internet

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Originally Posted by hoppy View Post
This 59m super yacht was last reported on marine traffic doing 16.4 knots 5 minutes ago (and counting)

This means it is possibly 1.36nm from that position. In the 5 minutes since the report it could have changed its course.

As it is a class A transponder on board, all boats within range will have gotten position updates every fey seconds. If it was a speed boat with a class B, then the position updates will have been sent every 30 seconds.

Attachment 104828

Sure, in a connected world it would be nice to have the internet AIS positions, but only for vessels beyond your AIS receiver range where 5 or 10 minutes between reports doesn't matter.

Internet AIS should not be used on the water, unless you are trying to find MarkJ because he owes you a beer





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Sure and as long as the app provides coding to indicate the age of the hit, I would be looking for him around 1.0 to 1.5 miles out.

Still a lot better than having no idea there is even a superyatch in the area.
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Old 07-07-2015, 08:38   #41
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Re: Live AIS Via Internet

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Originally Posted by DotDun View Post
How would you use old data for navigation?

Or is your intended usage for some other reason?
I simple color coding based on age would make it very useful.

Recent hits might be Green and as they get older they transition towards Red.
- a 1 minute old hit, I would know is very recent and the boat is probably very close to that position.
- a 20 minute old hit, I know he's about and have a general idea of where he is likely to be, so I can keep an eye out for him.

Let's say it's foggy.
- The guy with no AIS data has no clue what is out there. He doesn't know where to look or what to look for.
- The guy with internet AIS, has an idea of what boats are out there and a rough idea of where they are. He is then prepared to look for them and what to look for. If he is unsure what happened to a particular boat, he can call on the VHF referencing that specific boat by name and be more likely to get a response.

In an extremely congested area like NY Harbor, it would likely be of limited use other than having a specific name to call (of course live AIS is pretty limited use in that scenario as all the ferries, water taxis, barges, etc... are all criss crossing and changing directions so much, you are generally better off looking out the window than looking at the computer screen. Running down the Cheasapeak where traffic paths for ships are pretty predictable and boats are fairly spread out, it can be quite useful.

Yes, full blown live AIS is best but it also has a cost. That is why when it came out the focus was on large commercial ships not row boats.
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Old 07-07-2015, 08:41   #42
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Re: Live AIS Via Internet

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...I think I would know if I was driving an SUV along the beach. I was talking about charts that are just off a bit and show you running along the beach.
I think you misunderstood what I was saying. I wasn't suggesting that you were driving along the beach. I was suggesting that you were observing someone else's "boat" on the beach, but it is actually someone else driving with the crowdsourcing app running on his phone...

Quote:
Originally Posted by valhalla360 View Post
I wasn't talking about modifying the chart datum but taking note and making a mental adjustement...
...same issue. You make the incorrect assumption that it's a boat on the beach, so the chart must be wrong. So you make an incorrect mental adjustment to the chart that could lead to other incorrect conclusions on that chart, with potentially dangerous consequences.

This is the danger of having bad data, which can be worse than no data. With the cost of real, VHF frequency-based AIS receivers plummeting, I see no reason to mess around with far inferior crowdsourced information.

Sometimes the reason these technology things are done is "because we can." We'll see over time whether these apps that transmit your boat's location to the Internet get any real traction for serious use. Waze technology has worked for cars. But for boats, I think it's a novelty that boat owners will try out, and then realize it's a gimmick. They might use it on an inland cruise so the family back home can track their progress. But then the novelty wears off and the family stops watching. Then they discover how much it drains the phone battery. Then they forget to turn it off and people see their "boat" doing 80 mph down I-95.

I'm not sure that this is all it's cracked up to be. If someone wants to write a plugin for this, have at it. I think I'll take a pass.
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Old 07-07-2015, 08:45   #43
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Re: Live AIS Via Internet

I see no problem with internet based AIS as long as the time delay is displayed prominently on the screen. I don't know if that can be done.
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Old 07-07-2015, 08:46   #44
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Re: Live AIS Via Internet

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I simple color coding based on age would make it very useful.

Recent hits might be Green and as they get older they transition towards Red...
Except that OpenCPN already uses green and red color coding to indicate threat level of real AIS targets.
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Old 07-07-2015, 08:47   #45
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Re: Live AIS Via Internet

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Originally Posted by valhalla360 View Post
I'd rather have it all in one place and not have to flip back and forth between applications.

By this logic, you should run a dedicated AIS completely independent of your chart plotter.
But if you have AIS why do you need the internet AIS? You have all vessels that you might need to worry about the CPA on your AIS. My AIS tells me if the target is a sailing boat, cruise ship, a tanker etc. if I can't tell which ship in the distance that interests me, a compass bearing is more useful than a photo identifying which is which. If it gets to the point I want the photo, I can get online, but I don't see much point in it.


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