The Cuban Heiress by Chanel Cleeton

 This is a fictional story based on a real event. The Morro Castle was a luxury liner that traveled between NYC and Havana in the 1930s. It met its demise due to a series of mysterious and unfortunate incidents on one voyage. 

Catherine is on the ship with her fiance, his young daughter, and her nanny. Unbenownst to the fiance, she is playing the part of a wealthy heiress. Elena is on the ship, in disguise, for she too has a secret. Their stories are slowly revealed and come to a head the night disaster strikes the ship.

It's a good story and the historical aspect adds an additional level of interest. Enjoyable summer read.