Shore power must be one of the greatest inventions of all time. We can sit on our boats in the marina enjoying all the comforts of home - TV, heater and kettle all contribute to a life of comfort.
However, all the time we are blissfully unaware that down below the waterline our beloved boat's metal bits are happily dissolving away. Now you may be asking yourself why there is a picture of the surface of the moon on this page... Sadly this is not a lunar landscape but the surface of an anode fitted to a boat which was linked to shore power. The anode was only two months old and was 75% eroded. The problem here is that it was not the only anode on the boat and they were all as bad. The cost of having the boat lifted and the anodes changed came to several hundred pounds. Imagine having to do that several times a year... Worse still, imagine what would happen if all the anodes dissolved. The next thing to go is your more expensive metal bits, like aluminium casings of the out-drives, maybe your rudder, or propeller, how about the odd skin fitting below the waterline.
Why does this happen? Well as we all know sea water and metal don’t mix, but if your boat is built correctly, all the underwater metal bits will be electrically connected together with an earth wire. This helps protect the metal from corrosion. That is until you plug into shore power. You then become part of a large floating battery. Forget the 240Volts of the mains power, this does not cause any damage to your boat, it is the small galvanic voltages of this giant floating battery (usually less than 1.2 volts DC) that cause the problem.
So how do you prevent it? Check out our website for the full story...
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