Burns harbor/American century

[rh]

Marine Traffic displays ships out of shore coverage range as [Sat-AIS]. If you click on the ship on the map is will show the vessel type but no other data unless you are a paid subscriber.

I have found, unless in an area of heavy traffic, I can usually keep track of a vessel out of range by some dead reckoning from its last reported position and finding a [Sat-AIS] target of the proper ship type near the estimated position. I tracked the Nukumi across the Pacific and between Panama and Halifax with this technique.

With the Marine Traffic Android app you can pay a $1 fee and get sat tracking of a selected ship for 24 hrs.

[hausen]

The ais on the burns harbor and American century hasn’t been showing up for the last couple days. The last time I saw them they were halfway across Lake Superior. Why hasn’t there Ais been showing there location?

The free (i.e. at-no-cost) AIS data that the general public sees on platforms like Marinetraffic is only as good as the volunteer AIS data that gets fed into the system. When ships "disappear" from free public maps like the ones on, for instance, Marinetraffic, it means the ship has entered an area lacking in 'coverage', i.e. where no shore-based volunteers have pledged to feed data from their private/personal shore-based transponders into the stream of information that a service like Marinetraffic uses to build and display its free maps. When a ship "disappears" from such free public maps, it does not mean that she ship's own AIS equipment or service is interrupted or faulty. Regardless of whether a ship is currently showing on free public maps, the crews of any relevant vessel traffic that's actually out on the water physically nearby can still "see" (i.e. pick up) the other ship's AIS data transmissions and use that information for navigational purposes, as originally intended. As originally conceived, AIS data was transmitted via short-distance VHF radio signals. A ship's AIS transponder data was only intended to be able to be picked up by other nearby ships' AIS units (or that of shore stations) within 'line of sight' of VHF radio signal reception.

The system is switching (or has switched) to a satellite-based one now, meaning that users with certain data access privileges could theoretically see world-wide coverage maps showing the postion of every vessel transmitting AIS data. Services like Marinetraffic will show that kind of map, free of the phenomenon of "disappearing" ships, to the general public as well, for a fee.

[Bulldog]

The ais on the burns harbor and American century hasn’t been showing up for the last couple days. The last time I saw them they were halfway across Lake Superior. Why hasn’t there Ais been showing there location?