LIVE Stock Figures
24-48 Hour Dispatch (order before 4pm)
Expert Help & Advice
Galvanic corrosion occurs when there is an electrical current flowing between dissimilar metals in the presence of an electrolyte, such as water. This phenomenon can be attributed to galvanic cells that form due to the different electrochemical potentials of the metals involved. Here are the key factors that contribute to galvanic corrosion:
Dissimilar metals: When two or more different metals are in contact with each other, and there is an electrolyte present, galvanic corrosion can occur. Common metals found on canal boats include steel, aluminium, brass, bronze, and stainless steel. The farther apart these metals are on the galvanic series (a list of metals ranked by their nobility or tendency to corrode), the greater the potential for galvanic corrosion.
Electrolyte: In the case of canal boats, the surrounding water acts as an electrolyte, facilitating the flow of electrical current between the dissimilar metals. Water in canals can contain varying levels of dissolved minerals, salts, and other impurities that increase its conductivity.
Electrical connection: An electrical connection, known as a galvanic couple, must exist between the dissimilar metals for galvanic corrosion to occur. This connection can be direct, such as through metal-to-metal contact, or indirect, through an electrolyte that spans the gap between the metals, i.e. water.
Relative surface area: The relative surface area of the dissimilar metals in contact can affect the rate of galvanic corrosion. If the cathodic metal (less noble) has a larger surface area compared to the anodic metal (more noble), it accelerates the corrosion process.
a. Electrical isolation: Use insulating materials, such as gaskets or coatings, to separate dissimilar metals and prevent direct electrical contact between them.
b. Sacrificial anodes: Install sacrificial anodes made of a more active metal, such as zinc, aluminium, or magnesium which corrode sacrificially instead of the boat's vital components. These anodes attract the electrical current and protect the boat's metals. The choice of material depends on the type of water you'll be navigating in. Zinc anodes are suitable for saltwater environments, while aluminum or magnesium anodes are better for freshwater or brackish water. Anodes have a limited lifespan and will eventually wear out so regular inspection and replacement of anodes is crucial for maintaining effective corrosion protection. Selecting the correct anode.
c. Galvanic isolation: A galvanic isolator is an electrical device used to prevent or minimize galvanic corrosion in boats. It provides electrical isolation between the shore power ground and the vessel's onboard DC grounding system.
d. Regular inspection and maintenance: Routinely inspect the boat's metal components, anodes, and protective coatings to identify any signs of corrosion or deterioration. Replace anodes as necessary and maintain a proactive maintenance schedule.
By understanding the causes of galvanic corrosion and implementing appropriate preventive measures, you can significantly reduce the risk of corrosion and protect your canal boat's metal components.
For further information or technical advice, please call our sales team or visit one of our branches and speak to an advisor.
We’d love to keep you updated on the latest news and offers by email.
