should I install shaft anodes?

[Air O'Nautical]

Makes sense to me. However, in the unlikely event your shaft seperates from the transmission, the zinc keeps from ripping the rudder out of the bottom of the boat. Maybe a Marelon collar would be of help for that.

Some people afraid of that have put zincs inside the boat on the shaft as "keepers" just in case.

My friends Formula 41PC have shaft brushes standard equip.