A day on a sailing boat is a day in nature - sea, sun and wind.
You won’t need anything because you’ll be involved in a new and wonderful experience, you’ll savour the slow motion of the boat on the sea, and the sea breeze that mitigates the sun's rays.
Just put the following in a backpack:
sun cream, flip-flops, a beach towel, a book, phone charger, underwater (disposable) camera, sunglasses, a hat.
If you have chosen a weekend, add a sweatshirt for the evening, a pair of long trousers, a clean shirt for the following day and a nice dress if you decide to take a stroll in the village.
If your backpack is too small, use a cloth bag (like Ikea).
Do not bring a trolley case because there isn’t enough space on the boat, and you’ll end up sleeping with it!
There are bath towels, sheets, blankets and pillows on the boat.
Do not bring a hair dryer or hair straighteners, not only because outside the port we do not have electricity at 220 (but at 12V) but also because you won’t need them…