Norweigan Sky AIS Data

[shof515]

 

Browsing the marinetraffic.com website i see other ships with similar AIS messages

[BirdTravels]

Hah? That the ship has not been near a land based receiver since last night? Other services use satellite tracking. Or that the destination is out to sea.

[chengkp75]

Hah? That the ship has not been near a land based receiver since last night? Other services use satellite tracking. Or that the destination is out to sea.

 

Actually, the "destination" is entered by the navigating officer on the ship into the AIS system, so I doubt other tracking sites would say "out to sea". Even Marinetraffic will tell you that the ship is "out of range" but if you search for "all ships" they will display that screen for each ship. And satellite updates are usually a premium service you pay for, and they are only allowed 2 updates every 24 hours to limit the traffic on the satellite AIS, which is primarily used by government agencies.

[AmazedByCruising]

Actually, the "destination" is entered by the navigating officer on the ship into the AIS system, so I doubt other tracking sites would say "out to sea". Even Marinetraffic will tell you that the ship is "out of range" but if you search for "all ships" they will display that screen for each ship. And satellite updates are usually a premium service you pay for, and they are only allowed 2 updates every 24 hours to limit the traffic on the satellite AIS, which is primarily used by government agencies.

 

:confused: Do you mean a ship can only send 2 updates, or that you can only receive 2 updates every 24 hours? Sending would be strange because I see ships sending their position and goal every few minutes, receiving would be strange because you wouldn't need to "ask" the satellite (causing traffic) as everyone can "hear" it (or could use internet to get info from someone who does listen causing no problem for the satellite).

 

Interesting what a reason for such limiting could be though. I'm quite sure a single guest on a ship using satellite to look at a video of a cat would generate more traffic than all seagoing ships broadcasting their position every 30 seconds combined.

[FranknBeans]

The island stop often gets missed especially with the bigger ship at the best of time let alone after hurricanes.

[Mike D.]

I search for the NCL Escape's position and landed finally at the cruisemapper.com webpage. Currently (1:32 p.m. PDT) is shows many cruise ships apparently heading from Florida past Cuba towards Mexico and Belize. Found it interesting. http://www.cruisemapper.com/Norwegian-Escape-position?imo=9677076

 

Mother Nature is not being kind. Sigh.

[chengkp75]

:confused: Do you mean a ship can only send 2 updates, or that you can only receive 2 updates every 24 hours? Sending would be strange because I see ships sending their position and goal every few minutes, receiving would be strange because you wouldn't need to "ask" the satellite (causing traffic) as everyone can "hear" it (or could use internet to get info from someone who does listen causing no problem for the satellite).

 

Interesting what a reason for such limiting could be though. I'm quite sure a single guest on a ship using satellite to look at a video of a cat would generate more traffic than all seagoing ships broadcasting their position every 30 seconds combined.

 

No, the ship sends data all the time. The only way to "hear" satellite AIS is by being a government agency or through a commercial AIS tracking site, which is only allowed to get 2 updates a day.

 

AIS is designed to provide vessel information to other vessels within VHF (line of sight, or radar) range, so it can be displayed on the vessel's radar, much like the flight data is displayed on an air traffic control radar. Land AIS stations allow harbormasters and support services the ability to know what ships are in the area.

 

The IMO requires that every vessel of 300 GT or more be fitted with AIS, and since the initial regulation, it has been expanded, so that every EU fishing boat and river craft is required to have one. Even small pilot boats have them. It was estimated in 2012 that 250,000 vessels were equipped with AIS, and that the million vessel mark is not that far off today.

 

The problem with satellite AIS is that the satellite has to receive a very large number of transmissions, simultaneously, over its large footprint, and the satellite can only process 4500 time slots each minute, which is both for reception of data from the ships, and requests for data from earth. The satellite does not automatically transmit every vessel's AIS data every time it is received, only when it is requested by a terrestial site.

 

Because AIS is not encrypted, it is susceptible to spoofing and hacking, which is why governments are okay with limits on satellite access, since they don't want everyone in the world to know where every ship in the world is at every moment. Governments also don't want the satellites overloaded with commercial requests when they need it for SAR and Maritime Security.

[chengkp75]

I search for the NCL Escape's position and landed finally at the cruisemapper.com webpage. Currently (1:32 p.m. PDT) is shows many cruise ships apparently heading from Florida past Cuba towards Mexico and Belize. Found it interesting. http://www.cruisemapper.com/Norwegian-Escape-position?imo=9677076

 

Mother Nature is not being kind. Sigh.

 

Just know that Cruisemapper, when a ship is outside of land based AIS range, and there aren't many if any in Cuba, and certainly none that sell their data to commercial sites like cruisemapper or marinetraffic, will use the last course and speed, or the published itinerary and an estimated speed to post a location.

[AmazedByCruising]

Because AIS is not encrypted, it is susceptible to spoofing and hacking, which is why governments are okay with limits on satellite access, since they don't want everyone in the world to know where every ship in the world is at every moment. Governments also don't want the satellites overloaded with commercial requests when they need it for SAR and Maritime Security.

 

Why's that?

[shof515]

Why's that?

because our government is weird like the president we currently have :rolleyes:

[chengkp75]

Why's that?

 

Because of the last two words in the quote, Maritime Security.

[AmazedByCruising]

Because of the last two words in the quote, Maritime Security.

 

What exactly do you mean by Maritime Security?

 

24/7 coverage of all ships via UHF near shore, twice every 24 hour via satellite commercially for the rest of them, and multiple times each minute for non-commercial use. It's hardly a secret where the ships are.

 

Also, I wonder why someone would need to request data from a satellite. If I were a satellite, I'd be broadcasting all I knew, or at least send all my info to a landbased system for further distribution. I'm very impressed by the clever slot system Wikipedia describes which should minimize collissions during transmission, but as I said people are looking at cats on youtube nowadays, also using satellites.