How to Weld Aluminum Boat

How to Weld Aluminum Boat


Welding your aluminum boat is something you can never take chances with as it greatly affects the safety of the boat users. Unlike welding other materials such as steel or stainless steel, aluminum is often more challenging and requires additional skills and experience. But, as complicated as it can be, it is still possible to weld your aluminum boat quickly and correctly, whether you are repairing it or even fabricating a new one.

Things You Need to Know before Welding Aluminum Boats

Aluminum is one of the most challenging metals to weld, even for the most experienced welders. However, if you keep the following do’s and don’ts in mind, you should have a much easier time with this metal.

The Do’s 

1. Always Keep the Surface Clean

When TIG welding aluminum boats, cleanliness is one of the most crucial things you need to keep in mind. It is vital to make sure you always clean the metal’s surface before welding. Any dirt and other contaminants like oil and grease can affect the quality of the weld significantly.

Here you have to make sure both the base aluminum and filler wire are clean enough before use. If either or both are dirty, you typically end up getting weaker welds that are less impactful or even unsightly spatters.

2. Cut the Aluminum Just Before Welding

If you need to cut small pieces of aluminum when welding your boat, it is crucial to make sure you always do it just before the job and not too early.

Exposing the aluminum to air for long periods means it starts to oxidize. Since you cannot ground the oxidized imperfections, welding with such aluminum pieces can be quite hard.

3. Clean with a Hardened Steel Brush or Solvent

When cleaning the aluminum surface, you should use a hardened steel brush to remove any aluminum oxide from the surface. This brush allows you to remove the oxidation to improve the outcome without causing further imperfections.

However, if you want to remove things like grease or oil from your aluminum pieces before welding, you should use a good quality solvent as it does not leave any imperfections.

The Don’ts

1. Never Grind Aluminum

While it is common to see welders grinding other metals like steel before welding to bevel the edges or improve the surfaces, you should not do it for aluminum. Using a grinder on aluminum often leads to imperfections on the surface, making the material even harder to weld.

2. Avoid Oxy-Fuel Use

Preheating and cutting metal with oxy-fuel is common when welding, but if you are dealing with aluminum, you should never do it. The oxygen in the oxy-fuel can lead to aluminum surface oxidation, making it quite hectic to weld.

3. Do not Lubricate Aluminum

Any aluminum parts or pieces you intend to use when welding should never be lubricated. Lubricating aluminum makes it harder to clean when you want to weld it, and hence it gives you a more challenging time when you get to welding since you can not give it a thorough enough cleanup.

4. Never Use Compresses Air to Clean Aluminum

When cleaning aluminum, it is vital to make sure you never do it using compressed air. The compacted air has a significant amount of dampness that can affect the welding process.

How to Weld Aluminum Boat

Welding Aluminum Boats

The other crucial thing you need to understand when welding your aluminum boat is the actual process to follow. While most of the steps are similar to how you would weld any other metal, there is some twist to some of them. But, here are the most crucial steps to follow.

Step 1: Cut Your Aluminum Pieces

The first step when welding aluminum is always to cut the pieces into the sizes you want. As mentioned earlier, it is vital to make sure that you do not pre-cut too early before the weld as this allows for more time for oxidation to happen as you will expose them to air longer.

Remember, unlike other metals such as steel, you cannot granulate the flaws, given that this can ruin the material. For the best results when cutting the aluminum, always use a circular plasma segment, laser, or a circular saw with a metal cutting blade.

Step 2: Remove Oxidation

Even if you cut the aluminum just before welding, chances are there will still be some oxidation since some sections are exposed to the air even when the metal is in the roll. Therefore, you need to remove the aluminum oxide before you can weld, and here a hardened steel brush is handy.

Step 3: Clean the Metal

Next, you need to clean the metal to remove grease and oil, which are common contaminants that can significantly affect your welds’ quality. A high-quality solvent is the best way to clean aluminum because other things like workshop rugs and compressed air are less effective and come with different issues.

Step 4: Weld the Aluminum Boat

After all the preparation, the next step is welding the aluminum boat. TIG welding is the best way to weld aluminum as mechanical wire feed is not required. Instead, the welder feeds the filler to the puddle. Also, TIG welding is cleaner as the alternating current helps remove the oxidized layer from the aluminum surface when welding.

An easy way to ensure you get the best quality welds is by choosing a good tungsten rod. Also, ensure there is no excess flow of argon gas on your torch, and you can use a heat sink to ensure there is no warping.

Troublesome Distortions and How to Avoid Them

Troublesome Distortions and How to Avoid Them


1. Marine Fabrication, Repair, and Customization

  • Choose a Good Aluminum Grade: When working on boats, you need to use specific aluminum grades, with grades 5086 and 5083 being the most popular ones. They contain a significant amount of magnesium to provide extra strength.
  • Use an Appropriate Cutting Tool: You also need to make sure you cut it correctly, as this is a common source of distortion. Here, lasers are some of the most commonly used tools, but they can be restrictive on the material size you can cut. Therefore, a router is often more ideal, thanks to the larger table.
  • Boats Use Incremental Backstepping: As you weld your boat, you should use incremental backstepping to prevent distortions. Here you start from the boat’s center and work outwards. Also, you should ensure you do not concentrate a lot of the heat on just one area.

2. TIG Welding Aluminum Boat Propellers

Given how porous aluminum can be, if it is the material on your propellers, you can be sure they will end up soaking all kinds of junk from the water. Hence, when welding the propellers, you should allow all that junk to escape.

Therefore, to avoid issues, you should always start by cleaning the propellers thoroughly to remove any corrosion and use a good quality solvent like acetone afterward to remove contaminants further. Also, before you start repairing your aluminum propellers, make sure you practice enough so that you will not ruin them.


Aluminum boats can be hectic to weld, even for professional welders highly experience at welding other metal types. However, with enough practice, the right tools, and a good understanding of how to do it correctly, you should be okay. If you keep the do’s and don’ts highlighted above and use our step-by-step direction as a guide, you should master aluminum welding in no time.


  1. How to Weld Alumnum: The Beginner’s Guide – Universal Technical Institute
  2. What Kind of Welder Do I Need to Weld Aluminum? – Sciencing
  3. Understanding aluminum welding compared to steel welding – The Fabricator