Was not in the Engine Room but would say that a "Wiper" may have been to do with a sort of Greasers Aid ??
Cheers
Added As I thought looked it up!
Awiperis the most junior rate in theengine roomof aship. The role of a wiper consists of cleaning the engine spaces and machinery, and assisting theengineersas directed. The position is an apprenticeship to become anoiler, and has been for centuries. In modern times, a wiper is required to work on a ship for a specific amount of time, gaining what is referred to as "sea time."