Zoom in for more detail.
Ship Finder works by picking up AIS ship feeds used by commercial vessels and pleasure craft to transmit their name, position, MMSI, status and lots more.
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.
AIS (Automatic Identification System) is an International Maritime Organization (IMO) standard requiring all vessels of 300tons and over, and all passenger vessels, to carry an AIS transponder. This broadcasts information such as vessel name, position, speed and course plus information such as dimensions and the details of the current voyage. The AIS transmitter includes GPS capability for very accurate positioning. Increasingly many pleasure craft and smaller vessels can also be seen via the AIS systems as the owners are fitting low cost transponders.