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!
A
wiper is the most junior rate in the
engine room of a
ship. The role of a wiper consists of cleaning the engine spaces and machinery, and assisting the
engineers as directed. The position is an apprenticeship to become an
oiler, 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."