Final answer:
The ship's maintenance that is normally performed by navy personnel on board is known as preventive maintenance.
Step-by-step explanation:
The ship's maintenance that is normally performed by navy personnel on board is known as preventive maintenance. Preventive maintenance refers to the routine maintenance tasks and inspections carried out to prevent the occurrence of failures or breakdowns. It involves regular checks, cleaning, lubricating, adjusting, and replacing worn-out parts to keep the ship in optimal operating condition.