How to protect your aluminium boat from corrosion in salt water

Aluminium boats are a popular choice for boat lovers in Australia. Not only are they economical and easy to maintain, they also have a high strength to weight ratio, which means they move fast for the amount of power they require.


There are downsides to aluminium boats though. Like corrosion in salt water. Today, we’re delving into how this happens, and what you can do to protect your boat.


How aluminium boats get corroded in salt water

When an aluminium boat corrodes in salt water it does so as a result of galvanic corrosion. According to ScienceDirect:


Galvanic corrosion (dissimilar-metal corrosion) is an electrochemical process in which one metal corrodes preferentially, when in electrical contact with a different type of metal, and both metals are immersed in an electrolyte such as water.


Put simply, metals that are more active corrode faster, while less active metals corrode at a slower rate. On its own, aluminium corrodes at a fairly slow speed. But, when aluminium comes into contact with a less active metal, such as copper penny, corrosion speeds up.


This happens because when aluminium connects with a dissimilar metal in salt water, atoms begin to flow and the aluminium falls apart.


Use aluminium-safe anti fouling paint

Based on this science, it makes sense that aluminium will corrode significantly slower if it is not in contact with another, less active metal. Painting the bottom of your aluminium boat is a great solution for this.


An aluminium-safe anti fouling paint is your best option.


Why aluminium-safe anti fouling paint?

Anti-fouling paint will stop barnacles and other marine bio from building up on your boat’s hull, which makes it far easier to maintain and clean. It will also lower fuel consumption.


Aluminium-safe anti fouling paint should not contain copper, as this will react with the aluminium and cause corrosion. This is why we recommend only using anti-fouling paints that are specifically developed for aluminium vessels.


Before applying anti-fouling paint, you will need coat the hull with a layer of water-tight epoxy primer on surfaces, which are below the waterline of your vessel. Most importantly, follow the paint manufacturer’s instructions.


Need cover for your aluminium boat?

We provide comprehensive marine cover for recreational and commercial boat owners across Australia. Our marine underwriters can prepare an obligation free quote for you to review, based on your unique requirements. Get in touch to get started.


For more information on protecting your aluminium boat from corrosion in salt water, head here.