Aluminum Welding Boat | Dos & Don’ts You Need to Know

It’s time for your biggest ad potentially most dangerous project yet: aluminum welding boat! When it comes to aluminum boat repair, you can use TIG or MIG welding aluminum, especially if you know how to weld aluminum with a stick welder.

The trouble is that you know it needs to be perfect. When aluminum welding a boat, any mistake could prove fatal if your boat starts taking on water at sea because your weld wasn’t strong enough. That’s why you need to get some help.

This guide will let you know everything you need to know when it comes to MIG or TIG welding aluminum boats. By the end of the guide, you will know the answers to any questions you might have about the process of aluminum welding a boat, and be able to feel confident that your weld was successful. 

The Dos and Don’ts of Aluminum Boat Welding

black chain with red metal background

When it comes to renovating your boat, there are a lot of important things to remember to make sure your project is successful. 

Always:

Stay clean. Making sure that your aluminum and workspace are clean is critical when it comes to TIG welding. If your filler or your base is not completely devoid of foreign objects, the results of your weld will be weaker and less impactful.

Make sure you cut your pieces right before you start. Clean every piece of your project for better results, and remove any oxidized material from your surfaces. 

Never:

Don’t use a grinder on aluminum. These leave imperfections in the metal that will make it far more difficult to weld. Don’t use shop rags to clean your surfaces, either. These are good for countertops, but the dirt and debris that builds up on them make it a bad idea to pass this over the surface of your aluminum.

Never preheat or cut any part of your metal with oxy-fuel. This has oxygen in the source, which will lead to oxidation in your welds. No one wants oxidized weld projects. You also don’t want to use compressed air for cleaning. This air contains moisture, and that will react negatively with your weld.

Finally, you don’t want to lubricate any aluminum pieces that will get welded. When you mill aluminum for future projects, lubricating them will make them much harder to clean well enough for a weld. 

Cut Pieces Right Before Welding

If you expose untreated aluminum to air for extended periods of time, it begins to oxidize. This makes it very difficult o weld with the material, especially since you can’t grind away imperfections.

This means that welders working with aluminum should simply cut the pieces immediately before welding. Use a circular saw, laser, or plasma arc. 

Clean Every Piece with Solvent to Remove Grease and Oil

Using shop rags to clean your aluminum pieces will drag the grease and grime that has built up on the rag over your aluminum, causing dirt and imperfections to be placed on your surface rather than removing it.

Lubrication will make it hard to clean, and compressed air also contains moisture, which can cause your project aluminum to oxidize. Because of this, you need to clean your pieces with a solvent.

A high quality solvent can remove all of the grease and oil form your aluminum’s surface without leaving imperfections on the surface. Use this o ensure a truly clean piece. 

Remove Aluminum Oxide from Welding Surfaces

Aluminum oxide is bad for your welding surfaces. It will start an oxidation process that can compromise your material and the integrity of your weld will suffer.

For this reason, it is recommended that you use a stainless steel brush to remove the aluminum oxide from the surface of your welding materials.
When you remove oxidation, you will end up with a weld that has a significantly longer life span. 

Aluminum Boat Repair

Repairing aluminum boats can be difficult because of all the distortion likely to occur when it comes to marine vessels. Here are some tricks that can help solve that issue. 

Marine Fabrication, Repair, and Customization

For boats, you need a special grade of aluminum – usually 5086 or 5083. These contain some magnesium, while helps your strength without needing treatment.

There are a few different ways to cut your metal. Lasers are limited by the size of the table, so they may not have space to work your design properly. Water jets are pretty good options, but they make it difficult to prep your metal afterwards because this process leaves a lot of sand particles in your weld surface.

The best option for boat building is a router. This has large tables and won’t require edges to be prepped. It can’t really handle too much detailed cutting, and does require some cleanup, but it’s the best of the 3 options with an experienced operator.

Boats use a weld process called incremental back stepping. This helps prevent distortion by starting from the center of a boat and working outwards. Weld towards the center but sequence outwards. Skip every other weld in the process and try to keep the heat form getting too concentrated in any one area. 

TIG Welding Aluminum Boat Propellers

The problem with aluminum is that it can be very porous. This porosity means that boat propellers soak up a lot of junk on the surface of the water and end up with some corrosion. All these imperfections are waiting to make their escape, and unfortunately welding gives them that chance. 

First, clean your metal thoroughly. Use a burr to dig out thee worn surface and get rid of corrosion with some abrasives. Wipe with acetone when you finish cleaning.

Before you lay down your weld metal, use a low amperage setting on your TIG torch to clean the area with the arc. Run it over the arc without melting it to get rid of some of those last remaining imperfections.

Finally, make sure you practice before you actually try to fix propellers that need to be sea worthy. Boat propellers are pretty expensive, and you could do more harm than good if you don’t know exactly what you’re doing.

Learn on new 1/8-inch aluminum strips, then move to the junkyard for some scrap parts and practice running beads over thin edges. This will give you some experience understanding what happens to aluminum edges when you light it up and start to work with it. 

Metal Boat Final Weld Up Sequence - A Strategy to Prevent Distortion

Welds that will secure the perimeters of the plates need to be made first. These are your perimeter tack welds. After that, work on the welds that will hold the plates evenly. Use stringer chain welds for this. 

Finally, the welds that are most likely to cause greater distortion should be tackled first in a series of butt welds, then complete them in an order that puts the least likely welds to distort as your last sequence. Overall, you should never make a series of welds all in the same place. These should be balanced port and starboard and balanced top to bottom in a very controlled sequence. 

To avoid distortion, here’s the ideal sequence:
Tack weld all your perimeters. This should be a regular sequence, and only tack weld the minimum amount to keep the edges securely held in place, avoiding doing so much that you create weld shrinkage distortions. This sequence should relate to the eventual weld length layout. 

To avoid distortion, here’s the ideal sequence:
Tack weld all your perimeters. This should be a regular sequence, and only tack weld the minimum amount to keep the edges securely held in place, avoiding doing so much that you create weld shrinkage distortions. This sequence should relate to the eventual weld length layout. 

Next, chain weld your stringers to the hull plate. Make sure that you have room to put in butt welds. You should give around 12 inches to make sure you have room for the shrinkage that happens at the butt welds. Next, fixture the butt plates inside and outside your work.

Make sure your transverse butt welds are taken care of incrementally, usually by working towards the perimeter from the middle. Within the butt, take care of the inside first. Then, fix your longitudinal butt welds as needed. Treat any insert plates and being butt welds.

After those, begin welding the lengthwise seams with a regular sequence. Then, make longitudinal welds to the frames. Use minimal heal at the joints to avoid collapse that happens when heated. Finally, weld the attachments to plating and frames. These cause distortion, so proceed carefully and try to work at obtuse angles. 

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About the Author Gregory

Hi, my name is Gregory! I have been welding practically all of my life and love it. As I have gotten older I have started to weld less and less, so in order to continue my love for welding I created this website. I like to write about my experiences and help you all become welders. I hope that you enjoy the site!

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