The requested vessel with name TANDEM and MMSI:338098514 and IMO:0 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
TANDEM N/A 367656580 Jan 13, 2018 23:43 UTC
TANDEM II N/A 367629260 Feb 08, 2018 14:11 UTC

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