Hi David, yes, the ENI number goes with the aft/engine section, too. Today I came across inland tanker Stolt Madrid, ENI 02326328. In 2013 her bow section and mid-section were scrapped and the aft-section went to inland dry cargo vessel Rolf Hein, ENI 05501830. I've checked several photos on the internet which confirm that since 2013 Rolf Hein is sailing with ENI 02326328.

What's confusing me now is that Stolt Madrid had an IMO number and Rolf Hein is listed everwhere without...

That's certainly how it should be for IMO numbers. But I am less sure about ENI numbers - after all, I think that it is only a few years since the vessels changed ENI numbers if there was a change of flag. My understanding is that now numbers are till issued by national authorities with the first three digits denoting the country, but that those numbers now "stick" for life, regardless of flag. Grateful for confirmation on this, and when it changed.

So, strictly speaking, the 1955-built Holsatia was scrapped in 2004 under the name Vallesia - end of story (as I assume the ENI as well as the IMO number go with the aft/engine section) and basically this is a different ship... Fascinating...