James Alton


   Both of the rudder zincs on my Maramu thread into the stainless plates.  I would think that having the bolt threaded into the plate would be required to insure that you have a good electrical contact. When you tighten a bolt threaded into a plate, the threads are brought into metal to metal contact due to the tension, with just the bolt in a hole, maybe you have a connection and maybe not since nothing is really pressing the two bits of metal together.   Perhaps the threads stripped out on your rudder and someone in the past thought that they had fixed the problem by drilling through the plates and adding the bolt?  You could check for continuity between the zincs and the internal bonding system to see if you have a good electrical contact.  When I checked my zincs the OHM’s reading was 0.   I am thinking that you would be better off taping the holes for the next size up bolt.  You might in the future need to drill out your zincs to accommodate the larger bolt but it would not be a big job.  

All the best to you,

James Alton 
SV Sueño
Maramu #220

On Jun 22, 2018, at 4:45 PM, 'smilesbernard@...' smilesbernard@... [amelyachtowners] <amelyachtowners@...> wrote:

Hi there
My anodes are both held on by one single bolt that passes right through the rudder
I was a bit confused as to how the anodes were actually connected to any metalwork but the bot does go through one of the 5  stainless plates mentioned.
Does anyone else have this setup?
Not that convinced that the bolt passing through the stainless plate has sufficient contact area. Infact the yard took this off and i'm now wondering if the bolt threads into the plate at all or just pushes through a hole. Hopefully the former!

All the best
Older Maramu 162

On Saturday, June 9, 2018, 10:46:48 PM GMT+1, Beaute Olivier atlanticyachtsurvey@... [amelyachtowners] <amelyachtowners@...> wrote:


Hello Alex, Kent and Dennis,

the zincs are bolted into a stainless steel plate that is welded to the rudder shaft. There are 5 of them inside the rudder.
Alex, you need to drill the rudder with a 2 mm drill, on the other side of where your single zinc is attached, just to "feel" the stainless steel plate. Once you feel it, drill with an 8.5 mm and tap at 10mm. You will then put a new stainless steel screw into the new hole.
You could also try to find the next stainless steel plate above the one where you have your zinc, but this is more difficult, unless you have an accurate metal detector.

Bon courage.


On Friday, June 8, 2018, 2:54:53 PM GMT+2, Kent Robertson karkauai@... [amelyachtowners] wrote:


The bolt on the other side will be the same thread.  If the threads are stripped you may be able to rethread with the same size.  If you need to go larger, I’d rethread the other side the same so you don’t need two size wrenches.  With bigger bolts you may need to drill the zincs out to accommodate a larger bolt (I have to do that on all my zincs, they drill easily.)

S/V Kristy

On Jun 7, 2018, at 5:36 PM, alex.paquin@... [amelyachtowners] <amelyachtowners@...> wrote:


As part of the project to apply the new gelcoat on the hull, we were in the process of replacing the zinc anodes on the rudder (the older Maramu has 2). We noticed that one of the anodes was missing when Simpatico went on the hard. Further investigation revealed that the bolt or element on which the anode is screwed (inside the spade) onto is also missing, so we are unable to screw the second anode in place. Any thoughts of how we should proceed in this case. As far as we know, the inside of the rudder spade is not serviceable.

Alex Paquin


Hull # 94

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