I deal with the propellers only but the business I work at also has a department of machinest that deal with the shafts and anything related to them. As far was with the props we deal with both repairs and new castings. We make sure the propellers are balanced, pitched correctly, tracking with tolerance, free of cracks and other determental effects. Repairs arent too bad unless the blades are bang to hell and back *we have repaired props where the blade actually curled back to the hub), but new castings can be a serious pain. All the props we work on are Types of Bronze or Stainless and weigh up to 10 tons or so, Fun stuff