sdowney717
Guru
- Joined
- Jan 26, 2016
- Messages
- 2,264
- Location
- United States
- Vessel Name
- Old Glory
- Vessel Make
- 1970 Egg Harbor 37 extended salon model
Are marinas today worse as far stray currents than past years?
So it it getting worse or are people today more aware.
https://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems
I disconnected all through hull years ago, but I did leave the struts and shaft log bonded and the rudder posts and rudders. I have never seen any corrosion on anything.
So it it getting worse or are people today more aware.
https://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems
Bonding and Electrolytic Corrosion Due to Hot Marinas
Do not bond any thru-hulls or other immersed metal that can be electrically isolated. Specifically, keep your metal keel/ballast, your metal rudder shaft, your engine/prop, and all thru-hulls electrically isolated, from each other, and from the engine.
It's worth understanding the reason. In an increasing number of marinas, there are substantial DC electric currents running through the water. If your bits of immersed metal are bonded, the electric current will take the lower resistance path offered by your boat in preference to the water near your boat, and the current will flow into one of your bits of metal, through your bonding wires, and then out another bit of metal. The anodic bit of metal or thru-hull that has the misfortune to be on the "out current" side of the current running through your bonding system will also become "out metal" and will disappear, sometimes rapidly.
Your zinc is only intended to protect against the modest galvanic potentials and therefore currents that are caused by the dissimilar metals that are immersed and electrically connected together on your own boat. Your zinc is incapable of supplying enough galvanic potential to protect against substantial DC currents that may be flowing in the water. These DC currents in the water will cause electrolytic corrosion to your bonded thru-hulls or metal parts.
I disconnected all through hull years ago, but I did leave the struts and shaft log bonded and the rudder posts and rudders. I have never seen any corrosion on anything.