that's a great question. I usually wash out my delicate underthings in the sink in the bathroom and i wash my swimsuit in the shower with shampoo. I know that the cruise lines do a good job with dry cleanable items.
Carnival does have a special toward the end of the cruise. I would have liked to have used it but there was no place on the form to ask for cold or delicate wash. They must just throw it all in the same big washer and I wasn't willing to risk it! Like LisaK I always wash out my swimsuit myself. On our first cruise I washed out some delicates 2 days before we returned and they still weren't dry! Glad I had a plastic bag! Now I just take enough delicates for the whole cruise.
"A truly happy person is one who can enjoy the scenery on a detour."