Act of Piracy
Act of Piracy is a 1988 AmericanSouth African thriller film directed by John Cardos and starring Gary Busey, Belinda Bauer and Ray Sharkey. While enjoying an exotic cruise to Australia, a family yacht is taken over by terrorists. It is also known as Barracuda.
However, after a few days, it turns out that Laura is member of a terrorist organization led by Jack Wilcox Ray Sharkey, who wants the boat as a base for his operations. Jack takes over the yacht and only Ted can escape, and as a result, Mark and Tracey are kept as hostages.
Source: Wikipedia
