Zincs are sacrificial anodes that are placed on different underwater locations of your boat to absorb the electrical current that causes electrolysis. The electric current can come from anything from faulty wiring in your own or your neighbor’s boat or an electrical box that isn’t fully insulated. Electrolysis will damage propellers, struts, rudders, shafts and any other underwater metal parts. This is why Zinc Replacement is very important when maintaining your boat.
Galvanic corrosion is one of the biggest enemies of boats in the water. Moreover, Warm temperatures, some electric leakage from underground cables or stray current coming from other yachts in close proximity to each other can create galvanic corrosion too.
This starts at the sacrificial anodes on the vessel. Given the environment, this rate can happen slowly or rapidly. Once the sacrificial anodes have completely dissolved away on the boat, it will attack the more noble metals.
Eventually if not caught or corrected, the galvanic corrosion will dissolve all of the less noble metals and attack the more noble metals, until they are gone. The galvanic corrosion will work its way up the shaft and even into the engine corroding the heat exchanges and coolers. Once galvanic corrosion has made its way into the engine (providing the shaft seals don’t leak first and sink the boat), it is pretty much game over for the vessel. Replacing a large diesel or gasoline engine will cost you over $10,000.00 plus the cost of the new engine and the labor to install it. This is why zinc replacement is so important to the maintenance of the boat.