Given that inaccessible books on the high shelves could cause serious injury if they came down in rough seas, I assume they're fake and are bolted onto the wall.
The accessible books were all of the kind shown: odd volumes from series of encyclopaedias, multiple copies of biographies of obscure French philosophers, price lists from five decades ago, listings of the major events occurring in 1963, famous novels translated into Turkish or Serbo-Croat, ... . I guess this is the only way they can ensure that the books aren't stolen.
Maybe next time I go on a cruise, I'll take some of my own books and put them on the library shelves. It will serve as revenge for giving me COVID-19.