Greentext

I don't think this would work as a tourist draw in the conventional sense. The problem is that money doesn't change hands enough times to generate enough secondary revenue and taxes, since everyone is "locked in" for the duration and the ticket sales happen online (or somewhere else). Typical hotels draw people to business and tourism all over the city, and this proposal is the opposite of that. Just like a typical cruise, this puts the cruise-liner in position to run their own tax free economy/experience for guests during their entire stay; just build everything into the ticket price.

Then you add the fact that an aging and immobile cruise ship is permanently occupying a deep-sea launch/slip in your harbor. That mooring point is no longer generating anywhere near as much income as before, since people are coming/going at a much more lax pace and you can't use it for freight. And moving the ship around to accommodate other boats is likely going to require tugs which is time consuming and probably a huge PITA for the harbor.

Now, if you could anchor it somewhere remote where none of that matters, then you'd have something.