If you are as picky about your nails as I am. I would not take a chance when it comes to having them look bad while on a cruise. I would have my trusted local nail technician do them before I leave, and only use the ship nail tech services in the event of a needed repair.
So many people have such different tastes, some squared, rounded, flat arched, short, medium, long.
Not all techs are going to be proficient in the style that I prefer. Not to mention that if the ship carries a different product than what you have already it may be incompatible or the color may not match.
I had a repair done last year on the Triumph. It enabled me to keep the nail til I got home, but it didn't look very good and I think I paid $10! to get one nail fixed. (I had my own polish so she only polished that one nail) I'd get them done before you leave home.
get them done at home before you go if you can. YOu can expect to pay about double on the ship as compared to the cost at home. If you needed an emergency repair or fill on the cruise that would be fine, but as the other ladies have said i wouldn't get a full set done on a cruise.