>Are there ANY movies that filmed large parts of their script on an
actual ship at sea? (Surely there mast be some)
According to wikipedia; much of Master and Commander (2003) was shot
aboard the Rose (now named the Surprise and residing at the San Diego
Maritime Museum) with the storm scenes 'digitally-composited footage of
waves actually shot on board a modern replica of Cook's Endeavour
rounding Cape Horn'.
Many (most?) of 'mutiny on the bounty' movies have used real ships; of
course the last one, 'The Bounty' was made 24 years ago...