A bareboat charter is where you only rent the yacht/catamaran. You do not hire a professional skipper to come on board. You will need to hold the necessary qualifications to do this (see this FAQ to find out which licenses are recognized).
When chartering bareboat, you take full responsibility for the vessel and your crew. Under Croatian law, this means that you will not be able to consume alcohol while in charge of the vessel. Only once you have securely docked for the night will you be able to drink.
This is why many customers decide to take a skipper along on their yacht so that they can fully relax and enjoy a carefree sailing holiday!