The requested vessel with name CLONTARF and MMSI:0 and IMO:5426728 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
CLONTARF 9185645 503379000 HARBOUR Dec 14, 2017 08:58 UTC

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