Do I need a Galvanic Isolator?

See the Adverc Galvanic Isolator Technical Data Sheet.

1. Only if you (and perhaps your neighbour) rely on shore-power to provide a mains supply on the boat. 

2. If you wish to preserve your health!

The subject of electrolytic corrosion is a complex one, involving dissimilar metals, on the one hand, and differences in voltage potential, on the other.

In the first instance, sacrificial anodes are common place and are a fundamental part of the equation. In the second instance, connecting your vessel to a shore-power mains supply, or even mooring alongside another vessel, can significantly exacerbate the problem, creating an ‘earth loop’.

The Galvanic Isolator (Zinc Saver) will not affect the earth return passage of the AC current but it will block DC galvanic current flow, the cause of the problem.

2. Safety Considerations:

Unlikely as it sounds, faulty electrical appliances on boats could have lethal consequences if the path to earth is easier via an individual, the hull and water, rather than the recognised earth path.

Accordingly, the practice recommended by the BMEA (The British Marine Electronics Association) and RCD (European Recreational Craft Directive), is that all AC appliances and metal fittings on the boat should be earthed and bonded to the boat’s common DC ground.

This practice, whilst affording the necessary AC protection, does create the opportunity for galvanic corrosion to occur, which can be avoided by the use of a relatively inexpensive Galvanic Isolator (Zinc Saver). This will also reduce the erosion on any sacrificial anodes, that are fitted for electrolytic protection.

The general subject of electrolytic corrosion, in all its forms and with several causes, has been amply addressed in detail by several well-informed experts. For those interested in a further study of this phenomenon, we would thoroughly recommend the following sources of detailed information:

• Alastair Garrod - ‘Electrics Afloat.’
• John Payne - ‘The Marine Electrical & Electronics Bible’.
• Nigel Calder - ‘Boat Owner’s Mechanical & Electrical Manual’.
• BMEA - ‘Code of Practice for Electrical & Electronic Installations - Small Craft (4^th edition).’