Aluminum Boat Repairs

Extrusion metal

Aluminum Boat Repairs – Welding Solutions

With their lightweight yet durable construction, aluminum boats are popular for many boaters. However, like any boat material, aluminum requires proper maintenance and the occasional repair to stay seaworthy.

This article will provide a comprehensive guide on inspecting aluminum boats for damage, preparing and applying epoxy to cracked or corroded areas, welding repairs, adding protective coatings, and preventing corrosion through regular cleaning and storage best practices. Whether you are a new aluminum boat owner or a seasoned captain, use this guide to keep your vessel in ship shape.

Inspecting Your Aluminum Boat for Damage

About aluminum boat repairs, the first step is always to thoroughly look over your vessel. I know – inspecting every inch of your boat doesn’t sound like a thrill ride, but trust me, it will save you time, money, and headaches down the road.

Start by giving your boat a good wash. It’s easier to spot issues like cracks or corrosion once you’ve cleared dirt and gunk. Pay special attention to the hull, keel, transom, and rivets. These areas tend to see the most wear and tear.

Next, let’s talk about what you should be looking for:

  •  Cracks – Even hairline fractures in the hull can become big problems if left unaddressed. Inspect fiberglass boats for cracks on the gel coat. For aluminum boats, cracks occur more frequently around welded seams.
  • Dents – Minor dings aren’t a huge concern, but deep dents should be addressed quickly to prevent cracking. Use a dolly and hammer to pop out small dents. Larger ones may require professional repair.
  • Corrosion – Aluminum is prone to electrolysis below the waterline. Look for pitting or white powdery deposits. Catch it early and sand/grind it away before major damage occurs.

I recommend inspecting every square inch of the hull’s interior and exterior. Enlist a friend to poke around tight spaces. Make notes on your phone and take pictures of any issues for reference.

Once you’ve finished the initial inspection, could you repair any cracks, leaks, or dents as soon as you can? For corrosion, immediately start preventing further damage. We’ll cover repair techniques in the next section.

Thorough inspections should be done at least twice yearly – in spring before launching your boat and before winter storage. Consistent inspections allow you to avoid problems and enjoy smooth sailing all season long!

MIG Welding Techniques

Cleaning and Preparing the Damaged Area

Now that you’ve completed your inspection and identified any aluminum boat repairs needed, it’s time to clean and prep the damaged areas. Proper surface prep is crucial for achieving long-lasting repairs.

Start by thoroughly cleaning the repair area with mild detergent and fresh water. This removes any grease, grime, or residue. Use an angle grinder to open the area and create clean edges for cracks or holes.

Next, sand the area with 80-120 grit sandpaper to rough the surface. This gives the repair compound something to grip. Be sure to sand at least 1 inch beyond the damaged area. Acetone can help remove any aluminum oxide and oily residues after sanding.

Mask off surrounding areas you don’t want to repair using painter’s tape and plastic sheeting. This keeps epoxy drips or overspray contained.

For welding repairs, sanding and wire brushing are still required to remove aluminum oxide. Wipe the sanded area with acetone just before welding.

Pro tip: any time you sand or grind aluminum, wear a respirator mask. Inhaling aluminum dust is very hazardous to your lungs.

Follow these steps to clean and abrade the surface properly, and you’ll have a solid foundation for permanent, long-lasting repairs. Next, we’ll discuss specific repair products and techniques for cracks, corrosion, and holes in aluminum boat hulls and components.

Applying Epoxy and Sealants to the Damaged Area

Now that you’ve prepped the damaged area on your aluminum boat, it’s time to mix up some magic in a tube – epoxy! Regarding repairs, two-part epoxy systems are tops for filling cracks and corroded pits in aluminum boat hulls.

For small cracks and holes, I recommend a putty-consistency epoxy. Knead the two parts together until they have a uniform color, then press into cracks and holes. For large areas, opt for a thicker paste epoxy and spread with a plastic spreader.

Apply epoxy slightly thicker than the damage depth, working it into the sanded grooves. Seal the edges well and smooth with a spreader. For hard-to-reach spots, use a caulking tube system.

Tip: Work in small sections so the epoxy doesn’t kick off before you can apply it. Mix only as much as you can apply in 10 minutes.

In cool temperatures, epoxy may not cure fully. Use a heat lamp or heating pad to warm the repair to 75-90°F as it sets. Monitor often to prevent overheating.

Once cured, sand epoxy repairs flush with 80-grit paper. Wipe away dust with a tack cloth. You can apply flexible sealants like Flex Seal to build up thickness and create a protective barrier.

For optimal corrosion resistance, apply an aluminum-filled two-part epoxy primer after sanding, then top coat with antifouling paint. This seals the repair and prevents future pitting.

Follow the epoxy manufacturer’s instructions precisely, and you’ll have a solid permanent repair for many sailing seasons!

Welding Schools

Painting and Coating the Repaired Areas

The epoxy has cured – great job! It’s time to add protection and flair with primers and paints. Properly coating repaired areas on your aluminum boat prevents future corrosion and makes the repair blend in.

Start by scuff sanding the cured epoxy with 220 grit sandpaper. This roughs up the slick surface for paint adhesion. Could you wipe away all the dust with a tack cloth?

Apply two coats of aluminum-compatible anti-corrosive primer, following the product directions. Allow proper drying time between coats. I recommend a brush-on application for primer.

Once the primer has cured, lightly scuff sand with 400 grit sandpaper. This “key” helps the topcoat bond to the primer.

When selecting a topcoat paint, consider how you use your boat. For fishing boats, camo colors hide wear marks well. Bold colors look sharp on runabouts and wakeboard boats. Standard topside paint works for cruisers and sailboats.

Use a foam roller, brush, or spray gun to apply the topcoat in 3-5 thin coats, allowing proper drying time between each. Lightly sand and add another coat or two each season for upkeep.

Tip: Use painter’s tape to mask off a “border” around repaired areas for a pro-looking paint job.

Take your time with surface prep and application; your repairs will be protected from the elements while looking factory-fresh!

Welding Types

Ongoing Maintenance and Prevention

So you’ve repaired that damage, and your aluminum boat looks new! But the work isn’t done yet – maintaining your repairs and preventing future issues will keep your vessel sailing smoothly for years.

Here are some tips for ongoing aluminum boat care after repairs:

  • Inspect repaired areas regularly for cracks or swelling. Catching problems early makes re-repairs easier.
  • Every 2-3 months, wash the boat and scrub the hull with a Scotch Brite pad. This removes any residue or marine growth.
  • Check anodes frequently and replace them annually or when 50% depleted. This prevents electrolysis corrosion.
  • For riveted boats, inspect rivets for looseness or leakage. Tighten or replace as needed.
  • Apply a polymer wax 2-3 times per season. Wax protects the paint and topcoat from UV damage.
  • Store the boat out of water in a covered slip or garage during winter. Use supports to elevate and allow airflow.
  • Drain all water systems for winter. Fog the engine and perform annual maintenance.
  • Clean and inspect the boat thoroughly before launching in spring. Address any new issues immediately.

An ounce of prevention pays off where boat maintenance is concerned! Following these tips will save you money and hassle over the long run while extending the life of repairs.

Welding Aluminum Boat Repairs

Welding may be the best permanent repair option for major damage like large cracks or holes. Unlike epoxy, which simply fills the gap, welding fuses the aluminum for full structural restoration.

However, aluminum welding requires specific equipment and techniques. Here’s an overview of how to approach aluminum boat repairs requiring welds:

Equipment Needed

  • A TIG (Tungsten Inert Gas) welder with AC/DC capabilities
  • Pure tungsten electrodes and aluminum filler rods
  • Welding helmet with #10 shade filter
  • Metal brush or grinder for cleaning aluminum
  • Clamps to hold the pieces in position

TIG welders allow precise control and create clean welds on thinner aluminum. MIG welders melt the metal too quickly. Stick welding requires heavy-duty welding rods not suited for aluminum boats.

Prep Work

  • Clean surfaces to bare aluminum with a metal brush or grinder. Remove all aluminum oxide, grease, salt, etc.
  • Clamp pieces tightly in position. Misalignment will weaken the weld.
  • Mask surrounding areas from weld splatter. Aluminum sticks readily to finished surfaces.

Welding Technique

  • Set the welder to AC with a high-frequency start. AC promotes adequate penetration.
  • Use a foot pedal to control heat input. Keep the puddle small and move slowly.
  • Add 1/16-inch welding rods continuously to fill the joint as you go. Focus heat at the leading edge.
  • Allow proper cooling between weld passes. Quench hot areas with a wet rag.


  • Wire brush welds thoroughly when cool. This removes oxidation and improves appearance.
  •  Smooth any remaining rough areas with a flap wheel or sanding disc.
  • Wipe with acetone before applying protective coatings.

Welding aluminum boats takes practice and experience. If you’re uncomfortable with the process, hire an experienced aluminum welder for the best results. Either way, care for welded boats, which will last forever!

Major Hull Repairs and When to Replace

If your beloved aluminum boat has sustained major damage like large holes, long cracks, or deformation, you may face a tough decision – attempt to repair or replace the hull.

Assessing the severity of damage is the first step. Consider:

  • Size of affected area
  • Does location affect structure or aesthetics only?
  • Feasibility of accessing the damage for repair
  • Estimated costs and labor hours for repair

Minor hull damage under 2 feet, not affecting structural integrity, can be repaired cost-effectively. But at what point does replacement make more sense?

Factors favoring replacement:

  • Damage spanning over 3 feet
  • Multiple fracture lines or Swiss-cheese holes
  • Deformation of hull shape
  • Damage to keel or transom – critical structural points
  • Estimated repair costs exceeding 50% of hull replacement cost

The upside is that often, just the bare hull itself needs replacing. Your rigging, motor, trailer, etc. can all be reused on a new hull.

When opting for replacement:

  • Remove and dispose of the original damaged hull properly
  • Select a hull with optimal specs for your boating needs
  • Hire a professional to install the motor, controls, electronics, etc. on the new hull

While repairing a severely damaged aluminum hull is possible, replacement is sometimes the smarter choice for cost, performance, and safety. Assess each situation carefully before deciding.


Whether dealing with minor cracks and dents or major structural damage, this guide covers the full range of aluminum boat repair techniques. You can get your vessel back in ship shape with the right supplies and methods. While DIY repairs are suitable for many projects, don’t hesitate to enlist a professional for welding, hull replacement, or complex repairs. Their experience can ensure repairs are structurally sound.

The most important takeaway is preventive maintenance. Regularly cleaning, inspecting, and protecting your boat’s aluminum surfaces pays off exponentially in the long run by avoiding major issues. Your boat’s longevity also depends on proper winter storage, anode replacement, and addressing problems promptly. Equipped with this end-to-end knowledge of aluminum boat repairs and care, you can add years of enjoyment to the water.

Our aluminum craft has brought us many cherished memories on the waves. With proper care and maintenance, they’ll continue floating through countless adventures. Smooth sailing!


What are some advantages of aluminum boats compared to other materials?

Aluminum boats are super durable yet lighter than fiberglass. They resist corrosion better than steel or wood. Also, aluminum is easy to repair compared to composites. These are just a few reasons aluminum rules the waters!

What areas of my aluminum boat should I focus on when inspecting for repairs?

Check the hull, transom, keel, and joints closely since those areas are most stressed and worn. Pay attention to rivets or welds for cracking. Also, inspect below the waterline for electrolysis corrosion.

What’s the easiest temporary fix for a small leak in an aluminum boat?

For a quick fix, you can tape over small cracks or holes with waterproof aluminum tape. Just make sure to properly repair leaking rivets or holes later with epoxy or welding so water doesn’t keep seeping in.

Is JB Weld strong enough to repair cracks in aluminum boat hulls?

JB Weld is excellent for quick, small aluminum repairs. But I’d recommend a two-part marine epoxy for hull cracks longer than a couple of inches. The epoxy forms a stronger structural bond on aluminum than JB Weld over time.

After epoxy repairs, how long should I wait before taking my boat out on the water?

It’s best to allow a full 72 hours for epoxy to harden and cure completely – especially thicker applications. The wait is worth ensuring solid repairs before exposing them to water pressure. Bon voyage!

What’s the most common rookie mistake when maintaining aluminum boats?

Waiting too long to address corrosion! It may start small, but untreated corrosion expands quickly. Get on top of it fast with sanding and protective coatings before major pitting occurs.