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Old 09-06-2016, 22:13   #1
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AIS tracking

Hello, I am just in the process of installing a class B AIS in my yacht. What I am confused about is that I have several friends, all with class B AIS installed and working but they do not show up on "live ship" or similar AIS tracking sites. For the first time ever I seem to get a lot of unidentified pleasure craft showing on the map.
Is there something I need to do on "live ship" so that the vessel names show when the cursor is on the pink boat/square, OR is there something additional I would need to do after AIS installation so that my vessel name shows up on live ships, OR is there another / better app I can use on my laptop?
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Old 10-06-2016, 05:41   #2
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Re: AIS tracking

The internet sites (I sometimes use marinetraffic.com) are generally relying on a relay from an VHF AIS recipient to their site.


With MT, the relay stations are mostly volunteer, shore-based stations... although I've seen a ref that suggests some ships underway can perform the relay function, too. In any case, there are holes in their coverage.


IOW, it could be as simple as your friends not being in near enough proximity to one of the relayers.


I had to do nothing to cause myself to show up on MT. We're either "there" or were not, depending on whether MT's nearby relayers can pick up our (relatively low power) VHF AIS signal at any given moment.


Seems there was a big spike in MT's number of nearby AIS relayers over this last winter...


FWIW, there's another source of vessel location data that can show up on internet sites like MT, these originating from a smartphone/tablet app. In this case, the original source is not a VHF AIS signal, but rather a location message generated within the app. You generally won't see these guys displayed in your on-board AIS system -- unless perhaps your unit is also connected to the internet at the same time.


-Chris
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Old 10-06-2016, 06:39   #3
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Re: AIS tracking

AIS is a VHF signal and it works well for close ship to ship traffic.
It only has a range of 21 miles unless it gets relayed from a satellite repeater on a ship.

Powerboats tend to not transmit as far as sailboats, because the antenna is on top of their sailing mast.

The best way to follow any boat making an offshore passage is for them to have a Delorme Inreach or Spot device that sends a Satellite locations every 15 minutes no matter where on earth they are.
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Old 10-06-2016, 07:34   #4
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Re: AIS tracking

Try marine traffic com. They even show some satellite derived boats, mid ocean.

The basic idea is you see the others on your own unit (AIS, plotter, whatever you have onboard).

A) There are Apps that show what there is around you as they use your ship real time nmea data from the AIS,

B) BUT THERE ARE also Apps that use phone / Internet derived data. (!!! mind, no gsm towers offshore)

BEWARE.

Understand what you are looking at and what the limitations of each option are. Then sail safely.

I bet you will love your transceiver. We are receiver only here but upgrading to a transponder for our next passage.

Cheers,
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Old 10-06-2016, 07:38   #5
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Re: AIS tracking

Quote:
Originally Posted by Cotemar View Post
It only has a range of 21 miles unless it gets relayed from a satellite repeater on a ship.
Or you can afford the satellite tracking option on marinetraffic

Satellite AIS - Global AIS Coverage | AIS Marine Traffic

Though class B reception might be not as solid according to their website:

"Note that Satellite AIS tracking may be less effective for vessels equipped with Class B AIS transponders due to their lower transmission power."
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Old 10-06-2016, 08:08   #6
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Re: AIS tracking

Land based AIS tracking is not limited to the close inshore zone (say 60 miles) only.

At times land stations pick up signal from far offshore. I think this is due to the nature of the very short digital ping that contains all relevant data. (my guess, not a fact)

You will notice amateur shore stations in the Azores or Africa can at times show AIS targets up to hundreds of miles offshore. I am not sure if there is any ship to ship relay involved but I believe there is none.

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Old 10-06-2016, 10:37   #7
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Re: AIS tracking

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Originally Posted by conachair View Post
Or you can afford the satellite tracking option on marinetraffic

Satellite AIS - Global AIS Coverage | AIS Marine Traffic

Though class B reception might be not as solid according to their website:

"Note that Satellite AIS tracking may be less effective for vessels equipped with Class B AIS transponders due to their lower transmission power."
Class B has dificulties getting to the satellite. A friend of mine picked me up twice on my 2 week passage.

It's a good reason to think of Class A if you are getting a new boat for round the world stuff. Its only $3k




Sent from a stupid phone that replaces words with weird stuff.
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Old 10-06-2016, 11:22   #8
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Re: AIS tracking

These days, the top end vhf radios listen to 4 channels at once. The Standard Horizon (Yaesu makes their stuff, they have a great rep with hams) Matrix 2200 integrates VHF, AIS Receive, digital on channel 60 and whichever analog channel you are monitoring or scanning. The right chartplotter will repeat the AIS targets. If you need NEMA2000 the Uniden unit has that, or you can save $200 and the SH has NEMA0183 only. This essentially means that anyone can bother the commercial ships around them using digital calling. But there is probably no reason not to have AIS receive at this point. Keep the old radio as a spare.
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Old 10-06-2016, 11:35   #9
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Re: AIS tracking

Quote:
Originally Posted by Boat Boy View Post
For the first time ever I seem to get a lot of unidentified pleasure craft showing on the map.
The missing identification may be because the AIS owner did not register their MMSI code (https://en.wikipedia.org/wiki/Mariti...rvice_Identity). No registered code = no name
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Old 10-06-2016, 11:59   #10
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AIS tracking

Our boat is in the middle of an Atlantic crossing as we speak.

AIS is on.

Marinetraffic.com shows nothing at all.

Vesselfinder.com still shows us at La Palma (Canary Islands) since May27

Delorme Inreach shows complete track updated every 15 minutes from the start.

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Old 10-06-2016, 12:01   #11
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Re: AIS tracking

Quote:
Originally Posted by MarkJ View Post
Class B has dificulties getting to the satellite. A friend of mine picked me up twice on my 2 week passage.

It's a good reason to think of Class A if you are getting a new boat for round the world stuff. Its only $3k
Class B options exist, apparently. No price on the front page though.

ABSEA™ - Class B AIS Tracking
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Old 10-06-2016, 12:04   #12
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Re: AIS tracking

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Originally Posted by John_Trusty View Post
The missing identification may be because the AIS owner did not register their MMSI code (https://en.wikipedia.org/wiki/Mariti...rvice_Identity). No registered code = no name
No.

MMSI registration (in the unit) is required for the unit to transmit at all. No MMSI, no transmit. The same for DSC VHF radios: no MMSI registered, no DSC Mayday functionality.

Otherwise, the name of the craft may appear later as it is not transmitted in each transmit. Also, some receivers and plotters simply do not show the name for various reasons. But this is a separate issue.

No MMSI in the unit, no transmit and nothing visible on your plotter nor on Marinetraffic etc.

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Old 10-06-2016, 12:08   #13
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Re: AIS tracking

Quote:
Originally Posted by Cotemar View Post
Our boat is in the middle of an Atlantic crossing as we speak.

AIS is on.

Marinetraffic.com shows nothing at all.

Vesselfinder.com still shows us at La Palma (Canary Islands) since May27

Delorme Inreach shows complete track updated every 15 minutes from the start.

And this is what should be expected. Delorme is not AIS based and you are not paid with sat AIS services (or you are paid but you are not public).

All is fine then.

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Old 10-06-2016, 12:18   #14
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Re: AIS tracking

Quote:
Originally Posted by MarkJ View Post
Class B has dificulties getting to the satellite. A friend of mine picked me up twice on my 2 week passage.

It's a good reason to think of Class A if you are getting a new boat for round the world stuff. Its only $3k




Sent from a stupid phone that replaces words with weird stuff.
Some collected info:

Class A sat intended antennas are just different - more radiation upwards. These are what they sell as sat-AIS, which are otherwise identical internally.

(You want low gain stub for best sat B AIS pick-up otherwise)

You can have same kind of antenna for AIS B and improve the frequency of getting picked up.

I believe (but I am not 100% certain) the AIS sats are non stationary and so the signal is harvested as they fly over you, hence it is not full time tracking (I think).

Which sat AIS service were you subscribed with? Very odd only two ticks on a passage. How long was the passage?

I ask, as our friends who sailed from St Helen to C Verde right now were visible on the sat (as well as on a shore station) and the oldest sat report was about 8 hours old. This implies at least four ticks per day collected by the sat network. And they were not paid up with any sat service.

Have fun getting more visible,
Cheers,
b.
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Old 10-06-2016, 12:18   #15
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Re: AIS tracking

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Originally Posted by barnakiel View Post
And this is what should be expected. Delorme is not AIS based and you are not paid with sat AIS services (or you are paid but you are not public).

All is fine then.

b.
I paid $15 for Marinetraffic.com AIS satellite service for 30 days, but that was money out the window as they are showing NOTHING at all.

Vesselfinder.com seems to track better and its FREE

Yes. Delorme Inreach is a paid service, but worth every penny if you want to see your trip
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