Rudder Post electrolysis problem

[Royalllc]

My underwater boat cleaner who also replaces zincs said that the rudder post is getting electrolysis damage. Also, I am replacing underwater zincs almost every 2 month. (rudder, chaft, trim tab) I checked all the green bonding wires and it is all connected. Any suggestions? ( Long beach shoreline Marina salt water )

[Tree]

Are you connected to shore power and do you have a galvanic isolator fitted?

[Jeremyvmd]

Just because wires are connected doesn’t mean they aren’t broken/corroded under the insulation (don’t ask how I know). You need to check to make sure the wires themselves are intact (if you can’t a surveyor could do it for you). If all that is fine then it’s time to start looking for issues outside the bonding system or even outside your boat.

[Norseman]

In the meantime, hang a zinc grouper over the side hooked up to the rudder post.

[Tree]

If you are replacing zincs every couple of months, I would put my money on it being an external factor. Your zincs are clearly working well so I don't think its a bonding issue.

I will put my money on someone on the same pontoon having a bad earth on their boat and that is what is using your zincs - hence the galvanic isolator

[Royalllc]

Are you connected to shore power and do you have a galvanic isolator fitted?

Shore power connected but I have no clue what galvanic isolator is. I will have to do some research. Thank you