I've just been checking on the Port of Antwerp tugs that simply carry numbers not names. There has been some confusion on the site as to whether the names should include the word 'Tug' as this often is shown on AIS. But the more confusing thing is that, for example, 21 has been given an IMO number of 6503824, not just here but in Fleetmon, Marine Traffic etc. This can not be...the vessel was built in 2002 and if allocated an IMO number it would have started with a 9. The 6503824 is in fact the ENI number NOT an IMO number, presumably to fit in they should all now be prefixed with '0', so Antwerp tug 21 should be ENI number 06503824.
Allan