subject: Aluminum Anodes Can Save You Costly Downtime From Corrosion [print this page] Corrosion is one of the biggest threats that a boat or vessel faces in the sea. It not only damages the vital underwater metals, but it could also compromise the safety of the boat itself. To combat corrosion problems, sacrificial anodes are installed on the shaft of the ship. These devices are nothing but a specially made piece of metal that, when attached to your ship corrodes first to avert the wear-out from reaching your ship important metals. Magnesium, zinc or aluminum anodes are commonly used for this purpose.
Here is how it works: when two dissimilar metals come into contact with each other in water, there is a natural electric current that passes between the two metals. When this happens, the metal that is more active among the two tends to corrode first. This is where the idea for an anode comes in if an anode made from an active metal is attached to the shaft, the anode will corrode first. That is because the anode is now the most active metal in this entire set-up. Once it has corroded beyond a certain point, it must be promptly replaced so as to prevent the corrosion from reaching the shaft. Experts would typically recommend you to replace the anode once it reaches around 50% of its original size. This keeps the corrosion protection cycle on for an extended period of time.
While zinc has been the most common metal for these devices, there are other types such as magnesium and aluminum anodes that are also increasingly common. Each of these is suitable for use in different types of water conditions. All of these metal pieces are also referred to as sacrificial anodes because they sacrifice themselves (by getting eaten up by corrosion) so as to protect the expensive metals of a boat or vessel.
Since different marine environments call for the use of specific anodes, it is advisable to take the professional opinion of your marine electrician or boat manufacturer to know which anode to use. They might suggest magnesium, aluminum or zinc anodes based on the water conditions.
While zinc or aluminum anodes are best suited for salt and brackish water, you should use only magnesium anodes for fresh water bodies such as lakes or rivers. Another important aspect to remember would be never to paint the sacrificial anode or the surface that you are mounting in on. Paint will cut off a close physical contact between these two surfaces to keep the electrical continuity going on. This will prevent any anodes be it magnesium or zinc anodes from protecting your boats metals from corrosion.
It is important to seek the professional advice of your boat manufacturer or marine electrician before you make a final decision relating to the installation of zinc, magnesium or aluminum anodes.
