Galvanic Action - Stbd. Rudder Post

[jrbrein]

I have what looks to me like galvanic corrosion occurring on the rudder post and the base plate thru hole on the Stbd. side. The hose clamp attaches a bonding wire from the rudder post to the base plate. I replaced the cutlass bearings for both rudders 3 years ago.

Just so you know, I have a diver dive on my both every month and the rudder zincs have been wearing at a normal rate. The rudders and shafts are all Hatteras OEM bronze.

In the pictures you can see the 316 stainless hose clamp, 316 stainless nuts and of course the copper tinned wire. I know, why did I not use silicon bronze nuts? I have also gone through the boat with a volt meter and a submerged silver chloride cell and found all of my bonding points reading exactly -960 millivolts indicating that the zincs are doing their job. The prop shafts are slightly different and those zincs are wearing normally. The trim tabs are not bonded and they have their own zincs.

Would the stainless fasteners and copper tinned wire be enough to cause this galvanic activity? The Port rudder post has none of this.




Jon

 

[Captain Ralph]

It could be just patina or some erosion. I did not notice a bonding wire to the rudder tube.
And I do hate hose clamped on bonding wires.
So lazy and cheap of Hatteras to do this.
Is there a bolt of any kind on the tiller to attach a cable lug to?

 

[jrbrein]

It could be just patina or some erosion. I did not notice a bonding wire to the rudder tube.
And I do hate hose clamped on bonding wires.
So lazy and cheap of Hatteras to do this.
Is there a bolt of any kind on the tiller to attach a cable lug to?

Ralph,

Thank you.

The hose clamped wire attaches to the stern tube plate. I did that, not Hatteras. The bonding wire to the stern tube had long ago corroded off of it.

I agree with you that a better repair would have been attaching it to the tiller above and not hose clamping it to the rudder shaft which I will do. I will also replace the stainless nuts with silicon bronze.


Jon

 

[SEVEN]

Spray the corrosion with a little vinegar every once in a while if you don’t like the green look.