Galvanic corrosion is the most prominent culprit in the destruction of the parts of your boats that are submerged in water. Corrosion happens because your boat parts are made from different metals. Salt water is an electrically conductive electrolyte. When a less noble metal is connected to the nobler by the salty water, it begins to dissolve very fast, thus ruining your boat parts. Boat makers, therefore, created the magnesium anode, which is placed under the boat and stands in as the less noble metal. When the sacrificial magnesium anode dissolves, your ship is left intact. However, there are cases where the arrangement to break the circuit using a sacrificial anode fails to work and your boat parts get corroded anyway.
When the sacrificial anode has a small surface area
An anode's effectiveness depends on good electrical connection, which is determined by its surface area. As your magnesium anode dissolves, its surface area reduced and so does its efficiency. In case the anode is left to dissolve completely, the next least noble metal will start disintegrating. To avoid this problem, always replace your magnesium anode when it is halfway dissolved to preserve your boat.
When the water is warm or polluted
Warm and polluted water creates stray current corrosion which leads to an acceleration in the rate of dissolution of your sacrificial anode. When this happens, and you are not keen on checking the anodes, your boat parts might start getting eaten away. If you have docked your boat in an area with warm, polluted waters, you are advised to check anodes regularly to prevent this problem.
When you use the wrong type of fasteners
Galvanic corrosion does not only happen in two different boat parts, but it also occurs within the same region, when it is made of an alloy. It is common to find boat accessory sellers selling fasteners made from copper and zinc alloys. However, you should always insist on marine grade fasteners made of metals such as bronze and Monel.
Other important boat maintenance tips to remember include using galvanic isolators for the protection of the boat from dockside power issues and avoiding anodes that cause damage to the environment such as zinc and cadmium. It is also advisable to use magnesium anodes on freshwater boats only because the metal is not able to withstand the rate of corrosion which occurs in brackish and salty water. Finally, regular check up on your anodes will help you know when to replace them and avert disaster.
