Propeller services involves polishing or cleaning. When there is polishing it will be done to Rupert scale A. The Rupert Scale 'A' grade, which roughly equals a surface roughness of .65 microns, is apparently the highest quality finish that can be achieved by polishing the propeller blades.
The scale of Ruper A is currently measured visually with still images taken underwater. To achieve Rupert scale ‘A’ grade will require the divers to be highly experienced. When the propellers are coated with anti-fouling agents we will carry out cleaning instead of polishing so that the coating is retained.