What is Rudder Drop or Rudder wear down and How it measures?

On the third pull he said he was looking for an oil pressure drop That happened as well I told him that was a good procedure, but in the future he might want

Propeller Drop measuring in dry dock Now due to the weight of propeller and the clearance

measurement sheet app The poker gauge is inserted between the last two stern tube seals near the propeller to measure how far the shaft has dropped due to bearing

measurement sheet pdf What is Propeller Drop? How to Measure Propeller Drop? What is Pokers gauge? Er Saurya