White Cargo by Stuart Woods

White Cargo - Wendell "Cat" Catledge is sailing around the world with his wife and daughter.  Their alternator broke down and Cat decided to stop in Santa Marta, Columbia to get it fixed.  There they met Denny, who helped him.  As they were leaving, they took Denny on as crew.  Later, as they were sailing to the Panama Canal, they were waylaid by pirates.  When Cat woke up, both his wife and daughter lay naked and dead and the boat was sinking.  Several months later, Cat received a phone call that made him believe his daughter was still alive.