Vampirates

Vampirates is a series of young adult fantasy books. It is written by British author Justin Somper. The series is about two twin children, Connor and Grace Tempest, who get separated at sea. They are saved by two very different ships. Connor is saved by a normal pirate ship called the Diablo, Grace by the mythical Vampirate ship called the Nocturne. The word "Vampirate" refers to a vampire living on the Nocturne.