I remember changing out the disks at the place nearby where I worked watches each day just after midnight. Large banks of Winchester style disks in drives about the size of a washing machine. They had only a fraction of the capacity of a modern flash drive.
The first computer I took to sea was a ZX81, bought as a small kit. With the dreaded 16k ram pack plugged into the back (definitely not made with vibrating ships in mind.)
Then I moved onto the Oric, 6502 based, only way to save anything with that was via a cassette tape. Got a sound synthesiser board for it and then bollocked by the Old Man for making weird noises in the radio room ("Come on Captain, it's the radio room, it's supposed to have weird noises !"
)