I am doing a mix of finger food and spoon feed with my DD. I think finger food won't be a problem at all even in a cruise. You can give her anything, from cherry tomatoes, pears, melon, avocado, carrots, brocolli florets, cheese, pita bread, rice cakes, ham chicken... anything. You may find more difficult to give her some purees? I am not sure which type of facilities you will have in the cruise to prepare her food.
My daughter is EBF so for use it was easy to introduce solids at lunch time, usually and hour after her BM. Lunch time is finger food and we started with pear, carrots, banana, apple, melon, brocolli, sweet potato, rice cake. Dinner time was introduced a week after and it is spoon feed (just easier for us). We have tried breakfast but she does not seem very interested at the moment so we will keep trying till she decides that she is ready for it. She is 26 weeks now and we started weaning her at 23 weeks (adviced by HV). The first week I only offered her food 3 times and then started building it up as I saw that she demanded more.
Probably it will be easier for you to take with you some finger food such as rice cakes. Another option is to take some porridge with you. We are using "Four Gain Porridge" from Plum which you can mix with mashed banana, carrots, brocolli anything that you can get once it has been cooked. This should make an easy puree to give to your daughter.
Hope this helps you and enjoy your holidays.