The ship has to run, more or less on the time of the "time zone" it is in and therefore the hour is lost or gained on a daily basis. Recently on Jewel of the Seas a new idea of changing the time at Midday instead of Midnight was applied and met with huge approval from the crew as well as the passengers. This was applied to the easterly passage but I don't know whether the same benefits would be felt travelling westwards. I think it was a great idea eastwards though. .... Neil.
Have just returned from transatlantic QM2 5nights in New York. the clocks were advanced each night, arriving at dawn in New York, and on the return we retarded the clock by one hour, (their wordage) hope this helps.