As with any purchase you make with a credit card when the cared is swiped by the merchant and "authotized" by the card provider there is a hold placed on your credit card for that amount spent. It is NOT credited to your account until such time as the merchant makes the bank deporit. This is similar to what the cruise lines do.
They anticipate that you will spend a certain amount of money onboard. The place $200 holds "deposits" on your credit card, similar to your favorite merchant. Once you have reaced that $200, they will add andother $200 hold, and so on, and so on.
You have nothing to worry about except the card you are using for your onboard expenses. For example: We provided Carnival with a Visa credit card whtich had a limit of $2500 ( so we knew we were covered for all onboard expenses, and then some) as well we carried a MasterCard with a $1,000 which we used for off the ship expenses.
Bottom line, "don't worry unless you use a credit card with a samll limit, like $500 for your FunPass.
PS. Don't forget to notify your credit card company when and where the card is travelling to.