So the latest wheeze being talked about is putting asylum seekers on cruise ships.   

To me, this sounds like an idea of the top of someones head that will face huge problems if/when it is implemented. It is possible, of course, but let's think about a few problems.

1. Where is it moored?
If it is in a dock, that ties up facilities that would normally have a different purpose. You don't want it in a place where cruise ships are active, because it reduces capacity. The same applies to industrial ports. Also, no town is going to be particularly happy with this permanently added to their coastline.

ON the other hand, if it is moored off shore, how you get people and from to it is problematical. How is it staffed, for example? It will need fuel for electricity and water purification; how do you restock that? Similarly food and waste management. Then, if it is simply moored a little way from the coast, it will be as unwelcome for the townsfolk as if it is physically docked, but if it far enough out to be out of sight, you amplify all the supply problems.

2. How much does it cost?
If it is moored off shore, the fuel costs to produce pure water will be many times the cost of using a normal water supply.Similarly getting all other supplies to the ship will be multiples of the cost incurred by mooring on-shore. Equally, the logistics of getting asylum seekers on board and off more or less constantly will not be trivial.

Then cruise ships are designed to be economically efficient when they are full. No cruise ship with a capacity of 5000 will run at all effectively if there are only 500 'guests'.   That means when you first start operating you need to fill the ship immediately and then you have little or no capacity to add more.


3. How is it staffed?
Again, this is not too much of a problem if the ship is docked, but a huge logistical problem if it is not. I would expect you would need a staffing model similar to working on an oil rig.

4. How is it maintained?
The ship will need to meet and maintain all the regulations for a ship. For example, the evacuation procedures will need to be maintained and practiced regularly. Then the physical structures must remain seaworthy. All more costs.


So, in practice, I think the most viable option is to have the ship permanently docked.   But, as I say, that ties up facilities, and that will have a substantial cost as well, both financially and politically.