The only reason that one zinc would not corrode as expected is that it is not making proper electrical contact with the bonding system.
When you are hauled out, check for continuity between the problem zinc, and the rudder post in the aft cabin. You will likely find that the connection is broken.
Once you remove the zinc, you might quickly find the problem with the bolt or the zinc. If the problem is not obvious right there, you'll need to dive deeper into the internal structure of the rudder to find the problem.
Annapolis, MD, USA
---In amelyachtowners@..., <olaf_renos@...> wrote :
I found out that the zink anode on starboard side doesn't corrode. What could be the reason? What I have to check?
The zink anode on portside corrode as expected.
Thanks so much in advance
S/V Sayonara II, SM2K 392
currently in Martinique