Galvanic Isolator primer

If your boat’s made of metal AND you connect to a shore supply, there’s serious risk of Galvanic Currents, Stray electrical currents, and Earth Leakage causing enormous damage to your vessel. By fitting a Galvanic isolator, you can prevent this from happening.
When dissimilar metals are immersed in water, they act like a battery, and when the circuit is completed, an electrical current flows. These currents are called “Corrosion Currents”. More about that later. You just need to know is this…

“When Galvanic Current flows, it takes metal from the hull of your boat and deposits it on the bank side – you don’t want that”

galvanic isolator to stop hull corrodingCorrosion Currents can be quite small, but over a period of months, your boat could shed many kilograms of its hull, causing  pitting, and even holing.

I have personal experience of this – my boat’s hull has lost around half a tonne in weight through corrosion. And worse, it could have been prevented if I’d installed a simple galvanic isolator (sometimes known as a Zinc Saver), costing just a few pounds.

In fact, there are TWO types of corrosion current that are often mistaken for the same thing.


One is Galvanic Current – that’s the current that is caused by your boat’s hull’s interaction with other boats, and  metals that are naturally present in the bank side.

The other is DC Leakage. DC Leakage occurs when electric current “leaks” from your boat’s circuits and follows a path to the shore supply earth. In my personal experience, this kind of leakage happens to about 1 in 3 boats. It’s deadly, and  can damage your boat with devastating speed.

If you moor on a marina, the problem can be particularly bad. That’s because the earth of  the shore supply connects all of the boats together. If the zinc anodes on any of the other boats in the marina, or even on the pontoons are corroded away or missing, the anodes on YOUR boat will try to protect the other boats, (and the marina’s structures too). So if your anodes don’t seem to last as long as you’d like you may have just found out why.

And it gets worse still!

galvanic isolator zinc saver is the best way to stop a boat's hull corodingAs your boat’s hull starts to corrode, pits begin to form in it’s surface. Because the pits have a larger surface area than unpitted metal,  the corrosion speeds up even more. Before long, the anodes will have been dissolved away, and your boat is left entirely at the mercy  of corrosion – and it’s a boat-killer.


Fortunately, the problem is not difficult (or expensive) to resolve. What you need to do is to SAFELY break the electrical earth that connects your boat to the shore supply. Note, I say SAFELY.

A simple “Galvanic Isolator”, (an electronic device that blocks corrosion currents from flowing), achieves this, while allowing the safety electrical earth to remain intact. There are two types of galvanic isolators:

  • A Plug in galvanic isolator that simply connects in-line with your mains connecting cable.

  • A Wire in galvanic isolator which is part of your boat’s internal electrical wiring


Plug-In Galvanic Isolators >>>                      Wired-In Galvanic Isolators >>>



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