Your engine room log is filled out once a watch with machinery readings.
There is a space for writing starts and shutdowns and other bits of info of legal importance.
It can not be written in pencil, you cannot blot things out, they have to be lined out and initialed and you can't tear out pages to start over when you spill coffee on it-a hanging offense with most Chiefs I sailed with.
Saying that, other specific machinery may have readings done more frequently and have a log sheet beside it, to be filled out on rounds. Then you have your oily bilge book, ballast transfer record, boiler treatment log sheet, LO consumption sheet and whatever else a specific ship and regs deem important.