Note for your girlfriend
Curling your hair on a charter is a waste of time that could be spent enjoying the views. However my one hair care tip for sailing/swiming in ocean waters. Bring good conditioner. If you run a small drop of conditioner through your dry hair every day it will help prevent your hair from drying out and getting salt and sun damaged.
For the rest bring a nice hat or ponytail and just relax and realize that men are actually really attracted to beachy looking hair and that will naturally occur. Seriously go look at any style magazine people use lots of products trying to get beachy looking windswept hair. Sailing is great as you do not need any expensive products to acheive this look just go swimming every day and sail and enjoy yourself and your hair will look beachy and windswept just like stylists try so hard for.