The metal parts of the yacht are protected against the phenomena of electrolytic corrosion by means of anodes mounted on the stern, on the attitude correctors and on the propeller shaft nozzles. Check for their wear very frequently, as it depends also (and highly) on environmental factors like sea chains nearby, metal posts or shores, metal hulls moored nearby, electric devices, etc..
The replacement is necessary when the wear exceeds 50%.
Each time the yacht is lifted, check for the condition of the propeller, of the protective anodes and of the fastening system.
Replace the anode frequently.
For a spare part of the propeller shaft anode, specify the diameter of the shaft itself (105 mm).