The requested vessel with name RIVER THAMES and MMSI:0 and IMO:6525727 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
RIVER THAMES 8601563 577232000 CONSTANTA Dec 13, 2017 16:59 UTC

Also, you may try to find the vessel in our comprehensive Vessels Database or track this ship on the map.