@Walter Hinteler,
Some more trivia.
The
Alexander von Humboldt (I), known from the commercials for Becks beer ...
... was originally built in in 1906 as
Reserve Sonderburg. Acted as "Kiel lightship" until Kiel lighthouse was taken in service in 1968. Then, it was a reserve lightship on various position in the North Sea ("Elbe 1", "Weser", "Borkumriff", "P8", "P12", "Deutsche Bucht").
In September 1986, after a collision with a Liberian tanker, it was taken out of service and later became a sail-training ship ...