Simplify the following text for a Grade 8 native English-speaking person.
Original: Five Leander-class frigates played the role of HMS Hero and for continuity , all were repainted with the pennant number F42 of HMS Phoebe , the main warship used for filming .
Simplified: The series was about life on board a Royal Navy warship , the fictional HMS Hero . It was mainly filmed aboard the Leander-class frigate HMS Phoebe .