Hello Russell,
there are at least three websites where you can search by ENI number.On the site debinnenvaart.nl you have to click on item "Databank : De Binnenvaartschepen" and then enter the wanted number/or the ship's name, whatever your choice is.On the site binnenvaart.eu you should click on "zoeken", which means "search" in Dutch and fill in the wanted ENI. On both websites you can search with or without the beginning digit Zero. On the German site binnenschifferforum.de you have first to register and subsequently fill in the ENI in field "Erweiterte Suche", the site is in German language only.
Searching with google entering "ENI" plus 8 digits beginning with "0" will lead you to various websites, including the three sites given above.
Best regards Hans