First Light (The Daylight Cycle Book 1) by Kody Boye

Before the attacks, Rose’s life was simple.Before there was mass violence in America, she was a university student in Liverpool.Before her roommate was savagely attacked, she wanted to make the world a better place.That was before the zombie outbreak.Now, Rose and her best friend Lyra are forced to flee their flat and find refuge onboard a yacht with a group of armed survivors. Although safety seems likely on the open sea, it’s only a matter of time before a new outbreak occurs.