Boreades
Well-Known Member
The beginning of the story....
We keep our Beneteau 32s5 in Plymouth, Devon and have done for 12 years. Earlier this year, we asked the yard to lift the boat as usual, so we could do our routine annual hull maintenance i.e. antifouling and anode replacements. First shock, a call from the yard - "Did you know your anodes are missing and the propellor is seriously corroded?".
First action, a trip down to Mayflower to inspect the damage. Sure enough, the prop-shaft anode is completely missing, and the folding prop is so corroded, the gear teeth won't engage. Initially, I thought it was just Sod's Law, and the anode had fallen off, or it was my own bad workmanship when I fitted it a year before. Of course, once an anode's gone, electrolysis looks for the next sacrificial metal. In this case it was the propellor. Which is seriously bad news, and costly, but it needs fixing. So, a new prop has been fitted, that's £400 thank you very much, along with two shaft anodes and a new hull anode as well. At this point I'm thinking "Well, put that down to experience, we've learnt from it, we've taken extra precautions. Let's move on".
But then the plot thickened...
Just one day after the boat went back in the water, a letter arrived for the annual insurance premium renewal. That much was expected, what wasn't expected was a note that this year the insurance firm would like a copy of a marine surveyor's report on the condition of the boat. Apparantly it's normal practice now in the UK to ask for that every four or five years. So, another lift-out so the surveyor can do his inspection and charge me for the report. That's an extra £300 thank you very much. The said report has lots of boiler plate about what kind of boat it is, mostly OK, but then another shock. The new prop is already showing signs of corrosion, and the surveyor reckons my boat has an electric circuit problem, and needs testing by a marine electrician. I really can't believe this. By chance, I mentioned it to someone on the same pontoon. Guess what? He's got the same problem. Anodes put on only three months ago are already unfit for further use, instead on the year he'd expect. Back in the boatyard, I spot another boat in the slings being anti-fouled. I ask the guy working on the boat "Err, excuse me, hope you don't think I'm being nosey, but what are your anodes like?" Same story, only three months life.
Time to talk to the experts ...
That same day, a senior bosun at the yard said that lots of boats are coming out of the water with anodes that are much more corroded than past experience would have them expect. Boats that are using shore power seem to be most effected. But the effect isn't confined to the marina, boats on swinging moorings as far upstream as Torpoint (about two miles) are suffering as well.
A couple of days later, I caught up with Adrian Barlow of Ultra Marine, the resident marine electrician. He confirmed it's a general problem, but knew something I didn't. Marine biologists at the University of Plymouth, who have been studying marine life over many years have noted an increase in the acidity of water in the Tamar river. In some rivers and estuaries, that might not matter, but the Tamar valley is especially rich in heavy metal ores. As the acidity of the water increases, more metal is leached out into solution in the river. When it gets to the marina area, with plenty of disimilar metals on boats, and shore power leaking current through earth circuits, it seems you have all the ingredients for an electrolytic soup, buzzing with electricity. Then it's pot luck whether you have anodes of a slightly better - or worse - grade than your neighbour. Even if you have no shore power, you're in the circuit, and electrolysis will happen.
One thing is clear, it's not the marina's fault, and I'm not pointing a finger at them. Neither am I blaming it on global warming. I'll lift the boat again in two months to see how the anodes are doing.
Something else that worries me, is what happens to other boat owners, if we are only discovering this individually and by chance, if a boat is lifted. If my boating neighbours aren't lifting their boats often enough, they might get an even nastier surprise than I did.
A question for any one who reads this: Is anything similar happening in your area? I'm keen to hear from anyone else and compare notes.
Regards
Keith Macdonald
We keep our Beneteau 32s5 in Plymouth, Devon and have done for 12 years. Earlier this year, we asked the yard to lift the boat as usual, so we could do our routine annual hull maintenance i.e. antifouling and anode replacements. First shock, a call from the yard - "Did you know your anodes are missing and the propellor is seriously corroded?".
First action, a trip down to Mayflower to inspect the damage. Sure enough, the prop-shaft anode is completely missing, and the folding prop is so corroded, the gear teeth won't engage. Initially, I thought it was just Sod's Law, and the anode had fallen off, or it was my own bad workmanship when I fitted it a year before. Of course, once an anode's gone, electrolysis looks for the next sacrificial metal. In this case it was the propellor. Which is seriously bad news, and costly, but it needs fixing. So, a new prop has been fitted, that's £400 thank you very much, along with two shaft anodes and a new hull anode as well. At this point I'm thinking "Well, put that down to experience, we've learnt from it, we've taken extra precautions. Let's move on".
But then the plot thickened...
Just one day after the boat went back in the water, a letter arrived for the annual insurance premium renewal. That much was expected, what wasn't expected was a note that this year the insurance firm would like a copy of a marine surveyor's report on the condition of the boat. Apparantly it's normal practice now in the UK to ask for that every four or five years. So, another lift-out so the surveyor can do his inspection and charge me for the report. That's an extra £300 thank you very much. The said report has lots of boiler plate about what kind of boat it is, mostly OK, but then another shock. The new prop is already showing signs of corrosion, and the surveyor reckons my boat has an electric circuit problem, and needs testing by a marine electrician. I really can't believe this. By chance, I mentioned it to someone on the same pontoon. Guess what? He's got the same problem. Anodes put on only three months ago are already unfit for further use, instead on the year he'd expect. Back in the boatyard, I spot another boat in the slings being anti-fouled. I ask the guy working on the boat "Err, excuse me, hope you don't think I'm being nosey, but what are your anodes like?" Same story, only three months life.
Time to talk to the experts ...
That same day, a senior bosun at the yard said that lots of boats are coming out of the water with anodes that are much more corroded than past experience would have them expect. Boats that are using shore power seem to be most effected. But the effect isn't confined to the marina, boats on swinging moorings as far upstream as Torpoint (about two miles) are suffering as well.
A couple of days later, I caught up with Adrian Barlow of Ultra Marine, the resident marine electrician. He confirmed it's a general problem, but knew something I didn't. Marine biologists at the University of Plymouth, who have been studying marine life over many years have noted an increase in the acidity of water in the Tamar river. In some rivers and estuaries, that might not matter, but the Tamar valley is especially rich in heavy metal ores. As the acidity of the water increases, more metal is leached out into solution in the river. When it gets to the marina area, with plenty of disimilar metals on boats, and shore power leaking current through earth circuits, it seems you have all the ingredients for an electrolytic soup, buzzing with electricity. Then it's pot luck whether you have anodes of a slightly better - or worse - grade than your neighbour. Even if you have no shore power, you're in the circuit, and electrolysis will happen.
One thing is clear, it's not the marina's fault, and I'm not pointing a finger at them. Neither am I blaming it on global warming. I'll lift the boat again in two months to see how the anodes are doing.
Something else that worries me, is what happens to other boat owners, if we are only discovering this individually and by chance, if a boat is lifted. If my boating neighbours aren't lifting their boats often enough, they might get an even nastier surprise than I did.
A question for any one who reads this: Is anything similar happening in your area? I'm keen to hear from anyone else and compare notes.
Regards
Keith Macdonald
