If you get up early and plan to go too the serenity and the chairs are clearly taken but no one shows up within 45 minutes or so, is it rude to move their items for a spot you want?
Carnival has a rule that if items are left unattended for more than 30 minutes they will be removed. Problem is, they don't enforce it. I think if you see a chair that has been left that long you have every right to claim the chair as your own. And don't worry about appearing rude, the chair hogs are the rude ones!
"Life has no limitations, except the ones you make."