Common houseboats suffer hugely due to a unique natural feature called galvanic isolation. In simple words, galvanic isolation corrodes away the underwater metallic parts of the boat, when the floating boat is anchored at the marina and the boat’s power center has been plugged to the shore power center.  This usually occurs when the underwater metallic parts (anodes) is corroded away due to an electrolytic reaction with sea water.  This happens because then the boat becomes a huge electrode of a giant floating battery; the sea water acts as the electrolytic solution. Haphazard currents called galvanic currents are produced as a result of this process. These stray currents then again react in an electrolytic reaction with the underwater metal and corrode it away, more commonly described as being rusted or rust away. These currents are negative direct voltages and are in the range of less than -1.0 volts.

The underwater metallic boat parts like underwater fittings, propellers, hulls, and shafts are most affected by this type of underwater corrosion.  Galvanic isolators are extremely cost effective solutions to this huge problem of corroding away the boat. An isolator is technically a small device, which can be installed in the bottom or ground side of the electrical wiring of the boat. These isolators set apart the stray galvanic voltage and the metal parts covered by the salt water that causes the corrosion of the metals. Galvanic isolators can slow down the tempo at which the corrosion takes place of these metals by a considerably fair amount.

The pricing of galvanic isolators can vary from 69.99$ to a thousand dollars and above. The e-bay price listings of galvanic isolators can be found along with the above link.  Comparing the price of these isolators to the repair and replacement cost of corroded parts, it is a clear fact that these galvanic isolators are to be regarded as a standard and much necessary accessory to the vessel rather than a luxury or an option.

While buying galvanic isolators it must be ensured that the isolator meets required ABYC specifications. A galvanic isolator has been designed to block the negative DC currents, usually up to -1.2 volts. This is achieved by the functioning of the two sets of diodes of a galvanic isolator. The two sets are installed in opposite direction to one another. Galvanic isolators should block only the stray DC currents and not the stray AC currents. To ensure this, often a capacitor is installed along with a galvanic isolator.