How to Paint an Aluminum Boat

When you buy a new aluminum boat these days, many have a baked-on enamel paint job that looks almost as slick as gel-coated fiberglass. But many older or less expensive aluminum rigs have a dull gray look that’s not very attractive. That’s because they oxidize on the exterior, as opposed to skipping right to the corrosion stage like many other metals. And while that’s certainly preferable, it’s not exactly appealing to the eye. You want to make that dull gray aluminum look better than it ever has before? Then it’s time to prepare for a paint job.

Painting an aluminum boat in five basic steps:

  1. Sand off any old paint and/or surface contaminants.
  2. Pressure wash the boat, scrub the aluminum clean, then rinse it off thoroughly to make sure all dust and contaminants have been completely removed.
  3. Apply a primer coat.
  4. Pain the aluminum with at least two coats of an appropriate type of paint.
  5. After the paint has cured, apply a clear coat.
  6. Apply an aluminum-safe anti-fouling paint, if the boat will be stored in the water.

Good old-fashioned sanding is an important stage; a rough, course-grit sandpaper is best.

Sanding an Aluminum Boat

Just like painting fiberglass or wood, painting an aluminum boat begins with sanding away old paint and oxidation until you’re left with clean, shiny metal. This usually requires 80 or 100 grit sandpaper, which will leave behind some scuff marks. Don’t worry – this is a good thing. The tiny scratches and scuffs will help the primer and paint adhere to the metal. In fact, an aluminum surface needs to be etched so the paint has something to hold on to.

Good old-fashioned sanding is an important stage; a rough, course-grit sandpaper is best.

Naturally some safety precautions are in order when you sand aluminum, which can release oxide dust into the air. Safety goggles are a must, as well as a dust mask or respirator. You should also wear gloves and clothing which can be washed immediately after you complete the sanding.

Getting Aluminum Clean

What we’re looking for here is a shiny silver uncontaminated surface, to get the best possible paint adhesion. After sanding is complete, it’s helpful to wash down the aluminum boat with a pressure washer. Then, give it an old-fashioned scrub-down with a coarse-bristle brush and soapy water. Finally, rinse the boat down to remove all the soap and everything else left behind. After it’s been thoroughly washed down, allow the boat to dry completely before moving on to the next step.

Applying Primer

Aluminum boat paint jobs come out best when you use a primer that’s formulated specifically for use with aluminum. The primer will not only help the paint adhere to the boat, but will also provide an extra barrier layer that helps prevent corrosion or oxidation. Note: because oxidation begins shortly after bare aluminum is exposed to the air, you’ll want to apply the primer as soon as possible after the aluminum has been cleaned and dried. Many manufacturers recommend you do so just an hour after the boat has dried.

At this point, it becomes impossible to make blanket statements about the application of the primer and paint, because different types of products have different requirements. And you need to know this prior to applying the primer, because some primers should be painted over just an hour or two after application. Others need up to 48 hours to cure. Some should be sanded before the paint goes on, and others should not be sanded. The bottom line: you’ll need to read the instructions and follow them for each individual product.

There’s a wide range of primers to choose from but each has different characteristics and application requirements. Be sure to read the instructions of any specific product carefully, before slapping it on that boat.

All of that said, there’s nothing special about applying primer to an aluminum surface. Prior to application you’ll want to tape off the area(s) of the boat as applicable. The primer itself can be sprayed, brushed, or rolled on. After application a second coat may be recommended, but again, the specifics of multiple coats, dry times, and sanding between coats will vary from product to product.

Painting Aluminum

When the surface is primed and ready, it’s time to paint the aluminum. This is actually the easy part –it’s really no different than painting any other surface. Almost all paints will recommend at least two coats, however, and often (but not always) with a light sanding between them. In most cases you’ll want to use both a roller (for longer, broader surfaces) and brushes (for tougher areas with lots of angles, like chines and transoms).

Applying a Clear Coat

Applying a clear coat after you paint the aluminum will go a long way in protecting the paint and adding a glossy shine. It prevents damage from UV rays, corrosion, staining, and numerous other problems. Many clear coats can be sprayed on, and some should be applied with a brush; in those cases, foam brushes often work better than bristle brushes. Again, multiple coats are usually recommended and we’d always suggest following the manufacturer’s specific instructions.

If you like the silver metallic look of bare aluminum, you can also use a clear coat designed to keep it looking shiny and protected in its natural form. The right clear coat can chemically bond directly to the aluminum, prevent oxidation, and protect against corrosion for a decade or more.

Some clear coats (this boat was treated with four coats of Alumetron) can be applied directly to the aluminum, to maintain the metallic shine while also protecting the aluminum.

What About Anti-Fouling Paint?

If you want to leave your aluminum boat in the water for extended periods of time, anti-fouling paint may be necessary to prevent growth on the bottom. And regular paint and clear coat isn’t intended to do this job – you need a paint specifically formulated to be anti-fouling.

Warning: Never apply a coprous paint (any bottom paint including copper as the anti-fouling agent) to an aluminum boat. Any anti-fouling paint applied to an aluminum boat should be marked aluminum-safe, or it can set up a galvanic bath that will literally eat your boat alive, by causing the metal to corrode away. There are several types of anti-fouling paints that can be used on aluminum hulls without any problems – but check and check a second time, to be sure the paint you apply is safe for use on aluminum boats.

Make sure the anti-fouling paint you choose is formulated specifically for use on aluminum boats.

Okay: now your freshly-painted aluminum boat looks great on the outside. If the interior and other pieces-parts now look shabby in comparison, learn how to give things like vinyl, rubber, and plastic a face-lift, too. You’ll find some great tips on how to do so in Five Things to Do to Prepare Your Boat For Sale, whether you plan to sell that boat or not – and you probably won’t want to part with it, now that your aluminum boat has a completely new look.

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