Galvanic Isolator primer
Here’s a potted explanation of what Galvanic Isolators are, and why you very probably need one on YOUR boat……
If your boat is made of metal AND you connect to a shore supply, sometimes called an “Electric Hook-UP”,there is a serious risk of Galvanic Currents, Stray electrical currents, and Earth Leakage causing enormous damage to your vessel. A galvanic isolator can prevent this. When dissimilar metals are immersed in water, they act as a battery, and when the circuit is completed, an electrical current will flow. We call these currents “Corrosion Currents”. More about that later. What you 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 really don’t want that”
The current that flows can be quite small, but over a period of months, your boat could shed many many kilograms of its hull, leading to pitting, and even holing.
Believe me when I tell you that this is no fairy tale – my own hull has lost around half a tonne in weight through corrosion that could have been prevented for just a few pounds with a simple galvanic isolator (sometimes known as a Zinc Saver).
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 the metals that are naturally present in the bank side.
If you moor on a marina, the problem can be far worse. That’s because all of the boats are connected together by the earth of the shore supply. 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, not to mention 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! As the hull starts to corrode, pits begin to form in it’s surface and because the pits have a larger surface area than unpitted metal, the corrosion speeds up. 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 achieve is to SAFELY break the electrical earth that connects your boat to the shore supply. Note, I say SAFELY. You achieve this with a “Galvanic Isolator”, a simple electronic device that blocks corrosion currents from flowing, while allowing the safety electrical earth to remain intact. There are two types of galvanic isolators:
The other is DC Leakage, which occurs when current “leaks” from your boat’s electrical circuits and follows a path to the shore supply earth. In my personal experience, this kind of leakage impacts about 1 in 3 boats. When it happens, it can damage your boat with devastating speed.
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
If you’d like to know even more about Galvanic Isolators, you can read a 2 part article HERE
NEVER DISCONNECT YOUR BOAT’S SAFETY ELECTRICAL EARTH