Rangers will visit your boat in the evening to charge you a fee of 250Kn (€35) for 9-11 meters per day per vessel.
You can also purchase park entry tickets outside the park ( I got mine in Zadar Marina) for a considerable savings of 150Kn (€21) for 9-11 meters.
The official price list is here.
Howard [ Just Imagine ] 23-Jul-2007