The requested vessel with name CORNELIS GERT JAN and MMSI:234688000 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
CORNELIS GERT JAN 8410067 235004140 FALMOT Feb 25, 2018 14:21 UTC

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