The Pirate’s Curse by Toni Runkle

Abandoned, unaware of her true identity, 15-yr-old Bonnie faces danger after a run-in with the law. Sent to "reform sailing camp," she discovers it's a training ground for a secret society of pirate descendants. As she navigates sword training and a budding romance, a deadly secret unravels, forcing her to unveil the truth or risk a watery demise.