We went to Shabbat services on the Infinity. It was sooo funny. At first we were the only ones there. Then 2 couples (travelling together) showed up. The challah didn't arrive. They told us that it was in the oven and that we should ask for it at dinner. There was wine. Our sons did the bruchas..and that was about it.
At dinner, we asked for the challah. Finally the m'aitre d arrived with a box of matzos. (this was May). We laughed so much. Told him he was "a little late"!!!
We'll try again next Infinity cruise. But...don't count on much!!!
These services generally depend a lot on the early intervention of passengers on board. Generally, if there is a Jewish group on board, Hadassah or B'nai B'rith, as an example, they contact the front desk early in the voyage to arrange things. Celebrity is very accommodating in these matters. Individuals not traveling in a group can do this too, early on... just the way bridge players and others do. In no time at all, you'll have a goodly number to attend the services (a notice in the ship's daily program is usually part of this) and the ship will deliver the necessary and correct accomaniments for the service... promptly. If there is a rabbi or cantor traveling on the vessel, so much the better.
On most ships we've been on they've scheduled Shabbat services for about 5PM Friday afternoon. The ship usually provides challah and wine, and it's up to the passengers in attendance to make the service what they want it to be.