Ground isolated from water

[PK123]

I posted previously about the short life of my zincs and am thinking that this is perhaps something with Spring tides when the water level in my local marina almost completely drains leaving the keel for a few hours in the mud. The bonding is via a keel bolt. The prop and shaft are however left in the water due to the natural slope of the terrain and although bonded to all other underwater metals become grounded to earth (well mud!), rather than in the water. Id welcome any thoughts on that as a concept. At present Im hanging a zinc over the side and its been eaten quite rapidly along with the zincs on the prop shaft. Link to my earlier post with photos

 

[Don S/V ILLusion]

The earth (mud) and water are the same electrical potential.
As I recall from your prior post and the comments, you were advised to check your boat’s DC electrical connections are common and are all clean and secure. That comprises more than simply bonding the engine and ground. Have you done that?

 

[PK123]

The earth (mud) and water are the same electrical potential.
As I recall from your prior post and the comments, you were advised to check your boat’s DC electrical connections are common and are all clean and secure. That comprises more than simply bonding the engine and ground. Have you done that?

Yes absolutely - all checked. Ive currently disconnected the house and starter battery.