Galvanic corrosion and electrical anomalies
Q My 2015 Beneteau Oceanis 38 Ourania was purchased new last year and delivered on 6 June. I was pretty busy at the time so I only managed five short days’ sailing from Hamble before relocating her to Port Solent Marina: she had done 14.7 engine hours.
After a good clean for the new season I decided to carry out some manoeuvring exercises and have a gentle day-sail around Portsmouth harbour and the west Solent. The first indication of something wrong was an empty saildrive oil reservoir, followed by a gurgle and a gush of oil and water from the filler cap.
Thinking that the saildrive had a damaged seal, I arranged for a tow to the crane and a lift and hold to get the seals changed. So, when I received a call from the boatyard asking if I knew there was no propeller, I was surprised to say the least: I had run the engine the previous week, and the boat had held well just above idle on her springs to give the engine a little load. (This isn’t relevant to the story other than to note that there was a prop in March.)
There had been a terrible amount of galvanic corrosion in the 300 days that the boat had been in the water: the hull anode had gone completely, and the retaining studs had corroded back to flush with the hull. The saildrive had suffered a lot of damage, and while the bow thruster anodes were still in reasonably good shape for the immersion period, the bow thruster shaft looked pretty corroded and will need replacing. The pontoon the boat was on is the same one I have owned for 10 years: my neighbour’s craft and their electrical arrangements have not changed, and my previous boat suffered next to no galvanic corrosion over its lifetime in the same location.
Rusty
Of potential significance is the fact that one keel bolt is rusty, and all the standing rigging, turnbuckles, stanchions and safety wires are rusted where they touch each other, but nowhere else. Also, the FM radio has been turning itself on and off, seemingly randomly: I usually assumed when I found it on that I had been daft and left it on, but the marina crew who lifted the boat said it came on while they were lifting her, even though it was off again by the time I arrived. The only other electrical anomalies are that the iPod connector has not worked since handover, and the TV aerial has never been able to supply a signal to the TV.
The dealer sent out two electrical chaps to look at the fault: the first thought that the keel was incorrectly bonded to the engine, but Beneteau say that he was wrong. The second chap, meanwhile, said everything electrically was fine. (‘Fine’ is a relative term, I think.)
Interestingly, the aft stud that would have held the hull anode had separated into two pieces: one, with rust showing, was still screwed into the hull – probably the last thing before a sinking was on the cards. The stud with the bonding wire showed rust only on the fracture surface, and not anywhere else: I suppose this means that at some time the electrical integrity of the bonding to the anode was lost. Is this relevant? Do both ends of the anode need to be electrically bonded? I have had my shore power supply checked as well as the shore power cable, and there were no problems with either.
Galvanic isolator
So, what the heck am I to do? I am not qualified to determine the culprit, but no one wants to take responsibility: and while the lesson for me is to fit a galvanic isolator, I don’t feel that so much damage could be sustained without finding the cause. If it had been a rogue craft in the marina, for proximity reasons I can’t imagine I would have been the only one to suffer so much damage: my
boat was flanked by two long-term neighbours.
My partner thinks the boat is at fault and doesn’t want to go back on her once it has been repaired: her fear is that unseen corrosion has occurred elsewhere, and that the boat could be destined for an early end after what has happened. throwing money at it isn’t an option: you can only plough life savings into a boat once. i did contact Which? Legal, and they advised me to reject the boat as not fit for purpose: and while that’s certainly the case, i would rather spend what’s left of the summer sailing than litigating. i am rather fed up with locals saying that it’s my fault for not having her out of the water more often to check anode wear: the issue appears rather deeper than that, and i would have thought that most people don’t get their yachts out every nine months for a quick look-see? Stephen Agar By email
COLIN BROWN REPLIES
It looks like there has been some fundamental failure of the electrical system on your boat. I would not consider it normal or reasonable that such damage should occur in less than one year.
Assuming that you have not made any changes to the electrical system, then I think you would be justified in rejecting the boat as not fit for purpose.
You should take legal advice as the dealer (with whom you have a contract) will almost certainly dispute your claim.
It appears from your description and photos that your anode has wasted away completely and the next most anodic component (saildrive) has been attacked. Rapid corrosion like this is almost certainly caused by an external source of power – by ‘external’, I mean separate from the anode. This could be the 12V installation which you say has also given other problems.
I could speculate about the potential causes but that won’t help you much and may complicate any later proceedings, so I’ve given you the contact details of a local surveyor who has seen the boat at Port Solent and is aware of the problem. Subject to your instruction he will attend with an electrical engineer to try to find the problem.
The entire electrical system will have to be checked afloat and ashore to eliminate all of the possible faults. You are of course free to appoint your own surveyor, and may also wish to discuss the problem with your insurer.
I would ignore critics who say you should have checked your anode sooner: plenty of boats stay in the water for a year at a time, and an anode should last that long.