How to Stop Electrolysis on Aluminum Boats: Prevent Galvanic Corrosion

how to stop electrolysis on aluminum boats

You have an aluminum boat that you love to take care of and as a good boat owner should, you're probably searching for how to stop electrolysis on aluminum boats.

Aluminum boats are sturdy, light, and affordable, not to mention they can resist most forms of water damage. But electrolysis and corrosion are quite difficult to deal with given the metallic nature of the boat.

As such we hope to clear a few things about the process of how to stop it and prevent further damage to your aluminum boat.

On a side note, this guide should work for aluminum pontoons as well, so if you’re trying to live with an aluminum boat check the guide below.

But before that, let’s get a few things straight about electrolysis.

So What is Electrolysis?

Electrolysis is a process in which the chemical decomposition of material is induced due to the movement of electrons through an ionic solution.

Well, that’s a mouthful, but in a nutshell what this means is that electrolysis occurs when electricity passes through a material. Which is aluminum in this case and is exposed to an ionic solution, which is the water the boat is in contact with.

This reaction causes a degradation in the structural integrity of the material. Aluminum props aren’t safe from this either.

If you’re wondering why this even happens in the first place, we’ll talk more about it in the lower sections.

Oxidation vs Corrosion

electrolysis corrosion

Oxidation is only one side of a process called redox. Redox means reduction and oxidation, and they always occur together, with oxidation being the loss of electrons and reduction being the gain of electrons in a material. But we don’t really care about the reduction part of things because that has nothing to do with our boat. The oxidation part on the other hand is a big issue otherwise neither of us would be here right now.

Oxidation makes a material lose electrons which in turn makes it more reactive with its environment. This means that our material, which is aluminum, now wants to have stuff stick to it. Conversely, it also wants to stick to the random stuff in the environment.

The stuff in question is ions from the air or the water which will now stick to it giving it a dull sheen, and in worse cases may even weaken the structural integrity or create a hole.

Now we are all familiar with the term corrosion right? Rust is a very common example, but we have an aluminum boat, what does this have to do with our topic?

Well, corrosion is the worse case previously mentioned involving oxidation. Think of a magnet, like poles repel and opposite poles attract.

Aluminum after going through a process of oxidation now wants to stick to the ions in the water because they have opposite polarities. And sometimes this attractive force is strong enough to rip the aluminum ions from your boat and into the water.

Now your boat is a few aluminum ions less, and every time corrosion occurs you end up with a little less boat on your hands. This weakens the hull and will eventually create holes when left unattended.

This process is what’s called corrosion.

Types of Corrosion

It’s a bit complicated but there are a few types of corrosion.

Uniform Corrosion

As the name suggests this type of corrosion is spread evenly across the surface and is quite common.

Pitting Corrosion

Creates pits on the surface of the material and can be quite dangerous if all the corrosion is focused on a single point as this can make holes.

Crevice Corrosion

Occurs in crevices where two materials are connected but not welded together, such as where bolts are attached or under gaskets.

Intergranular Corrosion

This type of corrosion happens mostly on alloys, where it corrodes only a certain metal or part of the material more than others because alloys aren’t 100% perfect.

Stress Corrosion Cracking

Like its namesake, cracks are created when corrosion occurs in places where the material is stressed. Such as where the structure is bent or wherein it carries weight such as an outboard engine mount or a propeller.

Galvanic Corrosion

Occurs when two different metals are in electrical contact with each other either directly, or through a medium like water. This is the result of what electrolysis and oxidation can do to your aluminum boat.

Regarding the amount of corrosion, other factors also come into play such as temperature, surface design of the metal, alloys, and etc.

How to Stop and Prevent Electrolysis + Galvanic Corrosion on Aluminum Boats

galvanic corrosion on aluminum boat

As they say, prevention is better than cure, thus the best way to eliminate galvanic corrosion and electrolysis is to stop them from happening in the first place.

Paint the Boat Below the Waterline

Use some kind of anti-corrosion coating on your boat and paint it below the waterline. Aluminum is highly reactive with air and will form its own naturally occurring anti-corrosion coating above the waterline thus painting it is redundant, but you can still do so for aesthetic purposes.

Ensure That There are No Stray Currents

Electrolysis and galvanic corrosion occur whenever there are stray currents. So make sure that all your electrical equipment is properly grounded and isolated from the hull as much as possible.

Use a Sacrificial Anode

As the name suggests this is a type of material that you attach to the hull of your boat which forces any electrolysis process to target that material which is either magnesium or zinc. This will force the corrosion on the anode thus saving your boat from harm, but you have to change this often though.

Use Similar Materials

If you have an aluminum hull, use aluminum bolts, fasteners, etc. Galvanic corrosion and electrolysis only occur when in the presence of two different types of metal, thus if everything is made out of the same material, then these materials won’t react with each other.


In summary, electrolysis and galvanic corrosion occur under very specific conditions. Prevent as many of those conditions from happening and you can be sure that your aluminum boat will stay pristine for the years to come. This is how to stop electrolysis on aluminum boats.

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