John Rothwell, Austal's founder and largest individual shareholder, will step down as chairman after 37 years.
At 80, he will continue as a non-executive director.
Former US Navy Secretary Richard Spencer, known for his aviation background with the Marines, will succeed him.
Rothwell, who owns 9% of Austal, led its evolution into a global defence contractor with significant operations in Henderson, the US, and Southeast Asia.