I was on the Island Star in Sept 08 where you have to use US plugs adapters (flat two pin), so I feel quite confident that they are going to work on the IOS when I go next year. My GHD's worked absolutely fine. I have the GHD Model 4.0 B which state that they are 110-230 Vac, so check on the side of your GHD's to see which model you have and their voltage. Hope this helps....
It is polite to end a question with the word 'please'. That aside,Both sorts of plugs are available: North American standard, 110 volts AC. Outlet adapter is required for European standard. European standard (220 volts AC, round prongs). Stateroom outlets can accommodate appliances up to 1500 watts.
Hi I went on the Island Princess this year and took my GHD straighters, they are 220-240v 50Hz 30W (whatever the latter is).I took an american adaptor and they did not work.My mobile worked so beware. Maybe my GHD were too powerful, hope this helps? Have a good trip!