Accelerated anode depletion

Steadfast

Steadfast

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Steel boat in Chatham marina for several years, aluminium anodes. Arrived at Chatham with new anodes and antifouling. First taken out for maintenance after being berthed in the marina for about 27 months except for two months spent in Belgium. The anodes were maybe 50-70% depleted and replaced with more aluminium ones. I lifted the boat 16 months later to find all the anodes gone!! not much left but the studs. Same marina, same mooring but very different performance. The only difference is that in the first period the boat was plugged into shore power all the time and the second period the boat was unplugged when unattended. The DC electrical system is isolated when unattended except for bilge pumps and solar panels and both the AC and DC system is bonded to the hull via a single stud. This set up has been the same for both periods. Any ideas?
 
Any change in your neighbours?

This looks a bit like a stray current.

Exotically, does she have an impressed current system, such as a big ship has?
 
14K478 said:
Any change in your neighbours?

This looks a bit like a stray current.

Exotically, does she have an impressed current system, such as a big ship has?
Click to expand...
No Impressed current system. A small change in mooring. Previously moored alongside another steel boat of similar size nut now moored alongside a pontoon with concrete floats. I would have thought that that would help rather than make things worse.
 
It looks to me, a non-expert, as if your steel neighbour was your anode.

Do you have a galvanic isolator fitted?

PaulRainbow - one for you?​

 
Last edited:
Steadfast said:
Steel boat in Chatham marina for several years, aluminium anodes. Arrived at Chatham with new anodes and antifouling. First taken out for maintenance after being berthed in the marina for about 27 months except for two months spent in Belgium. The anodes were maybe 50-70% depleted and replaced with more aluminium ones. I lifted the boat 16 months later to find all the anodes gone!! not much left but the studs. Same marina, same mooring but very different performance. The only difference is that in the first period the boat was plugged into shore power all the time and the second period the boat was unplugged when unattended. The DC electrical system is isolated when unattended except for bilge pumps and solar panels and both the AC and DC system is bonded to the hull via a single stud. This set up has been the same for both periods. Any ideas?
Click to expand...
nothing new i have seen anodes fizzing in there, and someone i know who also had a steel
boat in there had an anode last only a few weeks, the place is one big battery which you
pay allot of money to moor there.
 
What may be (?) the only component of the conundrum that has changed is the antifouling paint. I know from my propeller studies that painting with Velux doubled anode life. I assume that with variation in copper salt content, some antifouling films may have different conductivity than others.
 
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