ultra rapid anode wear in the med

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blueglass

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Just had our first season in the S of F and am amazed at the rapidity with which my anodes disappeared. Fitted in May and diving under the boat in august I saw they were 90% gone! Just lifted the boat and they are down to nothing but the backing plates! The same anodes in uk waters always lasted a year in the water no problem.My query is how to overcome this without lifting and replacing twice a year. Can I fit oversize anodes? What about fitting propshaft anodes in addition to the engine ones - will that extend things? What damage might have occured from this seasons anode brinkmanship?
 
Many of the marinas on the continent have shore power with reversed polarity (pos neg reversed). This may be the reason you have lossed your anodes so rapidly. You can buy a gizmo, from B & Q for about 10 pounds, that plugs into your power sockets (type G Uk type) and checks for most connection faults.
 
Had a look at RD yesterday as she is not yet back in the water after SIBS. After five months on the Crouch she has very little anode wear. Previous boat needed checking every six months as she ate anodes. Both mercruiser bravo 3. Could it be some anodes last longer than others.
 
you could try hanging anodes from the stern, properly secured and connected to your system, this may decrease your fixed anode wear, but at least you will be able to keep an eye on things without getting wet. Do not forget to embark them before moving. As to damage I had a mate who was not connected properly and boasted of long life anodes, only to find his prop finished up looking like a piece of gorgonzola.
 
yes we have a built in indicator on our electric panel for reversed polarity and as you rightly say - this is a common feature down here. Not sure I understand how that eats anodes but my understanding of the whole concept is a bit sketchy to be honest.
 
There are lots of reasons for aggresive anode wear, but it is preferable to losing your sterngear.

I hang an anode of the back of my boat, I connected a cleat to the earth terminal on the galvanic isolator and hang the anode from this, if you have not got an isolator connect it to the back of the anode via the through hull fixing. It's important to make sure that whatever you make the connection to the cleat with is insulated at the anode end other wise that will dissolve and the anode will drop off!
 
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I hang an anode of the back of my boat, I connected a cleat to the earth terminal on the galvanic isolator and hang the anode from this, if you have not got an isolator connect it to the back of the anode via the through hull fixing.

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I don't even know what a galvanic isolator looks like so I probably don't have one! So if I understand you correctly - if hang anodes over the side, connected directly or indirectly to the back of the existing anodes i will increase protection?
 
Preferrable to clip onto existing anode post inside the hull, but the return on the engine will do, providing the drive system is connected properly, have known of these so called protective sytems being useless because of lack of continuity. i.e. the shaft to gearbox flexible coupling not being bridged, so you think you are safe but not so. if you require further info look at this www.clementsmarine.co.uk
 
"the shaft to gearbox flexible coupling not being bridged, so you think you are safe but not so"

I lost 2 propellers (£1500+) because the engineer that fitted flexible couplings omitted to bond the shafts to gearboxes. It took less than a year to totaly de-zincify them.
 
You will not increase protection, but your additional anode should corrode in preference to your fixed anodes, and will give your fixed anodes a longer life.

A "galvanic isolator" is a black box, roughly about the same size as a shoe box, and it will have all protected machinery connected to it by single cored cable (usually coloured yellow and green). They typically cost less then £100 and will slow the rate of anode wear substantially. They are simple to fit, easily a diy job, and you don't need any special electrical knowledge.
 
Where my boat is in South Africa, we have the worst corrosion rates in the world and two steel boats have sunk at their moorings this year already, luckily there are liveaboards nearby and both boats were saved from catastrophy.
If you are in a marina, you are electrically connected to the boat next door and possibly the pilings aswell. Check the millivoltage differential between your boat and the next boat. If it is more than 600mv + than the next boat (a good multimeter will measure it), get an isolating transformer fitted. Anode loss is also a sign of coating break down on a steel boat without any other outside influence.
 
I have a fairline with standard (as fitted by builder) anodes in Antibes and do not suffer unusual wear. I'd guess they are about 20-30% gone each year, though I change them at each annual lift out just to be on safe side. The boat is always connected to shorepower wehn berthed. There is a sort of reverse polarity in France (actually the neutral and live are both live, opposite sides of the sine wave, whereas in the Uk the neutral isn't live, so it's not quite "reverse polarity" but along similar lines) but that shouldn't cause your problem

So I wonder if you have some other problem? Some electrical fault maybe? Or are the anodes the right metal? Or a dodgy neighbour hull material wise, or electric wise? Remeber that thing where all boats connected to shorepwoer on the same pontoon are connected together via the earth wire, or something?

Which marina are you in?
 
the anodes are correct metal etc and being of no fixed abode we have had a variety of neighbours but as you say, at some stage we may have been moored next to somebody with a problem. The boat is currently out of the water for the winter in St.Raphael.
 
Talking of Anodes, we have had the anode on one leg disappear almost completely within 6 months and the anode on the other leg has barely been touched.

We are inthe same berth and have had the same neighbour for years on the side that has worn fast. In previuos years they have always worn at an equal rate.

Any ideas from those more thechnically qualified than myself?

We have renewed the worn anode and out her back in, will be intersting to see what the next few months brings.
 
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