We primarily use data reported via the World Meteorological Organization's Voluntary Observing Ship (VOS) program to provide a snapshot of current weather conditions at sea, worldwide. This data can also be used to track the progress of ships at sea. Many ships do not report their weather observations to WMO, or report only sporadically; these ships will not have records in our database.Ships with masked callsigns in the GTS are not displayed. Ships within range of several AIS receiver networks are shown when their positions are available. Additional information comes from the YOTREPS network of cruising yachts; YOTREPS positions are updated only once per day.