Luggage: I usually say (joking a bit) that once you have your bagagge done leave half of it at home and luckily you will use half of what you have left.
in some cases this statement is not exagerated at all.
Anyway the best is to make it simple: a few t-shirts and swimming suits are the main clothes you will wear most of the time. A warmer cloth for the evenings on the deck will be very suitable, i.e a polar
fleece. Street wear won't be very necessary, just for a ride in the island. Whenever the charter includes the trip from Barcelona to the island, a nautic light jacket or rain coat will be useful, though it will depend on the season, In august will stay in the rucksack most probably. A light sleeping bag is also welcomed, just in case it is a bit colder during night. The holidays include sheets (upper, lower and pillow). There are no towels. Regarding shoes, usually when anchored they are not used, but if you wish to take any when maneuvering, please choose shoes with a white sole (nautical style) so the deck does not get marked. For the rest a pair of sandals for the rides on land are enough.
To take list: sunglasses , sun cream, towel, cell charger, camera, drones, ecc...ideally with an USB connector.
The boat has a 220V inverter but it is not available the whole day. There is also diving material available but I recommend you to bring your own mask and diving tube.
Please note that luggage Should not be rigid, they could be of fabrics, such as the sports bags or rucksacks, thus we will be able to bend and keep them in the closet when you are onboard.