What a thoughtful treat for your daughter on her cruising day! A mani/pedi on board sounds like a fantastic way to relax and enjoy the journey.
Now, about those acrylic nails, it's understandable that your daughter wants to make sure she can fully enjoy the experience. It's a good idea to reach out to the spa onboard and inquire if they can service acrylic nails. They should have the information you need to ensure she gets the pampering she deserves.
After all, no one wants to miss out on a wonderful mani/pedi, especially on a cruise. Besides, you can explore different nail designs since you have more time to dedicate to your manicure.