A final hint. These are the entries for Ark Royal and Queen Mary in my museum.cfg:
[ITEM 79]
ClassName=CVArkRoyalasdf
[ITEM 80]
ClassName=PPQueenMaryasd
Weird names compared to the other units, because the entries don't match the ClassName entries in the data\sea\*.cfg file (trailing "asdf" resp. "asd"). If you rename the entries, these units won't show up in the museum. On the other hand I've got a lot of ships visible in the museum that are not listed in the museum.cfg at all.
Ok, you're right, got enough of this. Who cares? As long as it works...