Daughters of the Storm. The Bacchante Books, #1

A raging hurricane. A tiny fishing village in a distant land. A London nightclub dancer stumbles into the local clinic with the famous fire-fighter who carried her to New Zealand. The wife of an American shipping tycoon is on board his new luxury yacht as it battles the storm to reach the village. The young wife of a wine-maker struggles through mud, wind and rain to call for help, as her husband has been mortally hurt.
All three women are in labor. All three women give birth to baby girls. The clinic is destroyed by the storm, so no records survive. No one knows which baby belongs to which mother. Twenty-one years later, the American billionaire kidnaps all three young women, along with the men who were there when they were born, and takes them to sea on his yacht. Convinced that his wife claimed the wrong baby, he is determined to find which girl is really his daughter.
But the mega-yacht is old, and breaks down easily. As the strange voyage progresses through tropical Polynesia to New Zealand, crisis after crisis overtakes them. They are being stalked by something malign. Storms arrive and the engines give out. Reefs and shoals threaten. There's not just a question of identity at stake, but of survival, too.