Re: [Amel Yacht Owners] electrolysis on mast/boom connection

Danny and Yvonne SIMMS

Hi Eric,
thanks for the reply. The new inserts are a very dense material and I have only done a couple of gentle day sails with no spray flying since they were put in so I doubt if salt would have penetrated. The bushings are a tight press fit and they are in two pieces meeting in the middle with a collar at each end so removal would not be simple

From: "sailormon kimberlite@... [amelyachtowners]"
To: amelyachtowners@...
Sent: Saturday, 19 December 2015 5:24 AM
Subject: RE: [Amel Yacht Owners] electrolysis on mast/boom connection

My guess is that salt has penetrated the new insert and you have made another battery.
Did you try removing the new insert and washers and soaking them for 24 hours in something like salt away ?This stuff  dissolves salt crystals and is used to clean out outboard motors. I use it to clean the salt of the rails, deck  and hardware after a long passage. See if that makes a difference,
Or just as a simple experiment , wrap the bolt in a lot of electrical tape without the bushings and see if you get the same voltage- my guess is , you will not.
Obviously the new bushings worked for a while
Amel intentionally did not connect the rigging to the bonding. They had their own thoughts about this which was never explained to me. I have my own thoughts on the subject which I will not discuss here-That is another can of worms.
Fair Winds
Kimberlite Amel Super Maramu #376
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Friday, December 18, 2015 9:18 AM
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] electrolysis on mast/boom connection
Danny , I have voltage  readings in that area as well. What happens if you shut the breakers off to the mast and boom motors ? Does the voltage change ?
 Pat SM # 123
-----Original Message-----
From: Danny and Yvonne SIMMS simms@... [amelyachtowners] <amelyachtowners@...>
To: yahoogroups <amelyachtowners@...>
Sent: Fri, Dec 18, 2015 3:37 am
Subject: [Amel Yacht Owners] electrolysis on mast/boom connection
Hi all,
I have a problem I would like your collective wisdom on.
For a couple of years I have had electrolysis/corrosion occurring on the plates on the mast that receive the boom.
These two horizontal plates have a vertical bolt passing through them and through an alloy block through which a horizontal bolt passes attaching the boom.
The corrosion is exclusively on the plates on the mast.
I started by cleaning off and applying the appropriate aluminum paint systems. (And have done several times)
At the same time I did my best to isolate the stainless bolts from the alloy components with plastic washers. There are fiber inserts through which the bolts pass..
 This had no effect and the corrosion continued. Investigating with a multi meter I found up to 0.7 of a volt between the mast and the vertical bolt and the vertical bolt and the alloy block it passes through, however not the horizontal bolt.
 This voltage is enough to cause the damage.
On the advice of a marine electrician I drilled and tapped the various components (mast bolts, alloy block and boom) and connected them with electric cable which of course eliminated the differential but didn't seem to stop the corrosion. Logic seemed to suggest a "battery" was being created between this bolt and the block&nbs p;perhaps caused by degradation of the fiber inserts and invasion by salt crystals. 
So I had new ones made by a marine engineer using material he believed robust and with good insulating properties. After installing these I removed the connecting wires and joy... no differential. That was a few weeks ago. Now I find a differential of 0.4 of a volt...woe.
There is no differential between the two electric motors and the mast at rest. The corrosion is exclusively occurring on the plates on the mast that secure the boom
So now I have replaced the connecting wires and of course there is no differential. Question. Sho uld I connect the mast to the bonding system that connects to the zinc anodes on the rudder.
A thought, does Amel connect the mast to the bonding system? if so perhaps I have lost a connection.
The corrosion is getting serious so I need to find a solution
Kind Regards
SM 299 Ocean Pearl

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