If you're an act then working the cruises can be great(I'm told) as you would only be called on a couple of times a week to perform and the rest of the time you're free to enjoy the facilities.
As a band member you'll be paid less for a lot more work. There'll be afternoon dances everyday, the main acts to support/back each evening and then there's the "talent" competitions!
My ex-sister in law worked quite a lot on the cruise ships with a well established act and loved it. The money was very good too.
I've travelled as a passenger on a fortnights cruise(never again) and met an old friend who was working as a drummer with a trio on board. I kept bumping into him the whole time and he was always working.
I would presume that you would need to be a proficient dot reader too.