I thought I might be able to make use of some kind of AIS device so I was doing a bit of net-based research. I came across a webpage for ShipFinder, which also has a free app, so I downloaded it onto my Ithingy.
One thing I noticed almost immediately was some significant discrepancies in locations of ships. In particular, one of the BC ferries that seemed to be landing at Horseshoe Bay continued for about a mile along Highway 1 (that's the trans-Canada Highway), went right through the marina at Eagle Harbour and then traversed Lighthouse Park.
This mis-information is reflected on both the app AND the website.
According to the website:
"In summary the system works by:
◦Ships broadcast their position via radio
signals. (The system is called AIS).
◦This information is picked up by our receivers in the area.
◦The receivers send the data across the internet to our servers.
◦The map you are using gets its data from these servers over the internet."
So, my question is where does the system go wrong? At the AIS source broadcast? At the receivers? At the map (using a different datum?).
I can understand a ship being plotted late but not a ship being plotted on land.