Never done a Disney cruise, but I'll put money on it they've got better gear than a 20 year old Lifecycle. More and more hotels I stay in have ergs that allow me to run a manual workout and either dial in watts or at least dial in levels that translate to watts. I did a lot of work travel last year and only one hotel gym was lacking in that department.
-Ergs are all over the map in terms of calibration, some feel just like my CompuTrainer or my PT equipped bike, some feel much easier. I go by how I feel after the first five minutes or so of my first interval. IOW, I go by RPE instead of trusting the displayed watts. And if possible I use the same erg every time I visit the gym. My favorite bike at my local gym feels "soft" 245 watts feels easy for an hour so I record those workouts manually in WKO+ but adjust the power downwards to reflect the lower RPE relative to my PT.
Good luck,
Dave