Eric, One of my zincs also dissolves faster than the other . My electrician found that I only had 560 at the strap. He is trying to determine if I have a leak , but we also surmised that I may have degraded continuity . I assume that there is two stainless straps welded to the rudder post that are tapped for the bolts that hold the zincs. I wonder what the thickness of the plates are , as the only contact is , the threaded area. If mud or debris found its way between the threads I assume that could lower continuity. If we cannot find any leak or other cause for the low number my electrician suggested that we add a larger zinc with two bronze studs ( better conductor than stainless) through the hull and connect to the strap or quadrant. I cannot see how you could do any harm by putting a rod up through the hole, its just an empty void , but I don't think its going to help much to clean out the i nside . I also cannot see any harm in enlarging the hole . Rinsing the inside with a hose probably would help to get some old muck out .

I would be interested to know if you get the number up.

Pat SM123

-----Original Message-----
From: kimberlite@... [amelyachtowners] <amelyachtowners@...>
To: amelyachtowners <amelyachtowners@...>
Sent: Sun, Sep 4, 2016 5:41 am
Subject: [Amel Yacht Owners] Rudder , zincs, bonding, and cleaning inside

 

I have recently noticed that one zinc on the rudder is active and the other is not.

I believe there are S/S fingers inside the rudder which are attached to the rudder post. which in turn is attached to the bonding. Anyone have an idea as to why I might be having dissimilar erosion of the

zincs.

I also have put a piece of threaded rod into the hole in the bottom of the rudder and a lot of black silt and parts of shells come out of the rudder. Does anyone think I am doing harm to the rudder with this 2 foot long piece of rod?

I was thinking of making the hole in the rudder slightly larger. I would then insert a piece of soft copper tubing and attach it to a garden hose and basically power wash the inside, . Any comments?There would be enough space between the tubing and the tubing to allow outflow of silt and shell pieces.

Today I finished cleaning the wet bilge to inspect the bonding strap, everything was good. However when I measured the voltage at the strap with the silver chloride electrode in the water I only got -675

mv I dropped my zinc guppy in the water and it wend down to -725.I also checked it at the engine bonding and it was the same. I forgot to check it at the rudder.I will do that today. I assume it is caused by the inactive zinc. Again, any ideas?

Fair winds,

Eric

SM 376 Kimberlite in Lon Island, NY.

Any ideas why? I assume it is the inactive zinc on the rudder