‘Ratings’ is a general term for a wide variety of skilled seafarers in support roles in all departments, the work can involve a wide range of tasks essential to the safe operation and maintenance of the ship.
There are several routes you can take to become a Rating, depending on the area you decide to work in. You can get paid to train through an apprenticeship, or use your current skills and experience needed for a variety of hospitality services.
Taken from Careers at Sea. Find out more here: https://careersatsea.org/careers/choose-your-role/ratings/