Zincs_Ship repair yard Macduff, North East Scotland UK _ Sacrificial zinc anode on painted welded, corroded propeller housing.
Whenever different metals are placed in a conductive liquid, such as salt water, you create a battery. If you connect these pieces of metal together, current will flow. This current, trying to equalize the conductivity of the metals, will be removing metal from one of the metal pieces. This removal is called "electrolysis". If the piece being removed is the zinc in your flashlight battery that is good, but if one of the pieces is your propeller it is bad. When you pull your boat to do the bottom you may wonder what those pitted, ashen-white pieces of metal are on your shaft, rudder or possibly on the transom. These are called zincs and, as luck would have it, are made of zinc. The zincs you use on a boat are called "Sacrificial Anodes." Zinc is used because it has a higher voltage in the water so the current will be more inclined to flow from it than from your propeller. A galvanic anode is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal structures from corrosion. They are made from a metal alloy with a more "active" voltage (more negative reduction potential / more positive electrochemical potential) than the metal of the structure. The difference in potential between the two metals means that the galvanic anode corrodes, so that the anode material is consumed in preference to the structure. The loss (or sacrifice) of the anode material gives rise to the alternative name of sacrificial anode.
Size: 5120px × 3413px
Location: MacDuff, North-east Scotland, UK
Photo credit: © MediaWorldImages / Alamy / Afripics
License: Licensed
Model Released: No
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