How To Remove Oxidation From Fiberglass Boat

Keeping a well-maintained gel-coat is essential to protecting a boat’s fiberglass. It also looks good; what looks more attractive than a stain-free, shiny gel-coat? Keeping a boat well-maintained isn’t quite as difficult as it was in years gone by, but there’s still work that needs to be done.

Oxidation is a natural side effect of weather, environment, or possibly chemical influence. Most, if not all, boats will need a good clean and buff regularly. Ideally, you’ll do this before winter sets in.

There are a lot of products available to remove oxidation from a fiberglass boat, but it’s important to choose the right products and use them correctly; otherwise, you might damage your boat.

Signs of Oxidation

Unless your boat is brand new and religiously maintained, chances are it will show signs of oxidation. You should be able to tell easily if your boat’s hull needs some attention. Signs of oxidation include a chalky, dull surface, yellowing, and possibly a rough and pitted feel.

Light oxidation can be dealt with yourself, but with heavy oxidation, it might be wise to call in a pro. The gel-coat on your boat is what protects the boat itself from damage; every time you scrape against something, or strong sunlight shines on your boat for a long period of time, the gel-coat provides a buffer.

However, if you don’t maintain it, that buffer will gradually wear away. If you don’t properly remove oxidation and clean your gel-coat, it will eventually need a lot of attention. That will mean a lot of time, money, and work.

So, it’s best to keep your gel-coat in good condition, starting with removing oxidation.

Surface Prep and Removing Oxidation from a Fiberglass Boat

The first thing you’ll need is a good oxidation remover. There are plenty of suitable products available online, but make sure to do some research before using the product to make sure it’s suitable for your boat. It’s best to use the least abrasive oxidation remover you can; otherwise, you might end up removing too much of your gel-coat.

Meguiar's M4901 Marine/RV Heavy Duty Oxidation Remover 1 Fluid Gallon

If in doubt, test your product on a small, unseen area of the hull first.

Since you need to go over your deck thoroughly several times during this process, you will need to invest in a good orbital buffer. Be careful when using the buffer, since if you use it incorrectly, you might end up damaging your boat.

DEWALT Buffer/Polisher, Variable Speed, Soft Start, 7-Inch/9-Inch (DWP849X)

It’s important to get the right balance when using your orbital buffer to remove oxidation from a fiberglass boat. If you hold the buffer in place for too long, it might cause a divot in the fiberglass or wear away the gel-coat. However, you do need to cover the boat’s hull thoroughly. Work in small sections, and run the buffer over the section 2-3 times.

Once you’ve done this, change the “bonnet” or buffer pad on the orbital buffer, and use the new pad to remove the oxidation remover.

Now, it was mentioned earlier that it’s wise to choose the least abrasive oxidation remover. This is true, but if the oxidation on your boat is severe, the product you’ve chosen might not have had the right effect. You may need to repeat the process with a stronger product.

Be sure to check the hull carefully once you’ve finished. No matter how thorough you think you were, you may have missed some hard-to-reach spots.

Cleaning Stains and Polishing

Over time, most boats end up with a few stains. They don’t have to be something you just live with, as there’s plenty of things you can do to remove stains.

First, you’ll need a good stain remover. A light stain might come off with a rubbing compound for boat hulls and a cloth, but you might also see tougher stains. A fiberglass stain remover is probably your best bet.

Star Brite 098932 Star Brite Fiberglass Stain Re-, 32 oz.


Be careful when using products like these. They often contain acids and harmful chemicals, which can be dangerous for humans. You should never rinse off the product into the water, and be sure not to let the stain remover sit on the fiberglass for too long.

Read the usage instructions carefully, and stick to them.

Once you’ve followed all of these steps, it’s time for a polish. Now, polish is more than a quick touch-up; it needs to be sturdy enough to withstand the coming winter season. Use the orbital buffer (with a fresh buffer pad, of course) to apply the polish, the same way you did the oxidation remover.

For the shiniest hull imaginable, give the boat two coats of polish.


At this point, you’ll have already spent plenty of time working on the boat, and it no doubt looks amazing; shiny and pristine.

However, it’s important not to leave it here. If you don’t give the boat a good waxing, the hull will go back to being dull in just a few days. You need to seal in all your hard work with a fiberglass boat wax.

Collinite 925 Fiberglass Boat Wax, 16 fl. oz.

You’ll need two coats of wax for the best results, and it needs to be applied by hand. This is time-consuming, but the results will be worth it. You might also want to add a gentle layer of carnauba wax before running the orbital buffer (again, with a fresh buffer pad!) over the hull for the last time.

Related: Best Cleaner for a Fiberglass Boat


Hopefully, this process should have left your fiberglass hull and its gel-coat looking shiny and stain-free. It’s a long and arduous job, but if you keep on top of maintaining your Gel-coat, the end result will be worth it.

You might only need to complete the full process once a year since the hull might only need a clean and wax during the warmer months. There are plenty of suggestions and instructions online, and you can easily find the perfect cleaning routine for you and your boat.

Remember, the more work you put into it, the better your fiberglass hull will look.

Proper Equipment and Safety Tips

It’s been mentioned earlier, but it bears repeating again: these are harmful chemicals. Always use proper safety gear when using any of the products or tools listed here. Follow the instructions to the letter.

Be careful when using the orbital buffer. If you’re using the buffer to remove oxidation from a fiberglass boat, you should put the product on the cloth or buffer pad in an X pattern. Make sure you put the buffer pad flat against the side of the hull before you turn it on. Otherwise, oxidation remover is going to fly everywhere.

Using the right tools on your boat will make the difference between a beautifully shiny hull and a hull that looks even worse than before. Orbital buffers are a popular choice since it’s quicker and more effective than buffing by hand.

However, if you aren’t experienced with using orbital buffers, tread carefully. Improperly used buffers can dent or scratch a fiberglass hull, and end up getting more product on you than on the hull. You can easily hurt yourself since the buffers can be very heavy [1].

An orbital buffer is not the same as a rotating buffer. These are heavy and can be very dangerous for someone who doesn’t know what they’re doing. For an amateur or first-timer, an orbital buffer is a much safer choice.

When it comes to buffer pads, you can choose between microfiber pads and terry cloth pads. Your orbital buffer will probably come with some pads, in which case those are likely the best suited for use.

If you put too much product on the buffer pad, it will skid over the surface of the hull and won’t work as effectively. However, if you do accidentally use too much product, pat the (powered off) buffer along the hull, which will leave little blobs of product. Keep doing this until you have the right amount of product left on the pad.

Then, when you start buffing in earnest, you can work along the blobs of the product, working them into the hull.

Waste not want not.


For many people, a boat is more than just a possession. It’s something that carries happy memories or hopeful plans for the future. It could be their pride and joy, lovingly cleaned and waxed every other week.

It might be an investment, in which case it’s even more important to keep it maintained and looking good.

All the cleaning, polishing, and waxing that goes into maintaining a boat isn’t just about vanity. It’s essential to keeping the boat in good condition. The process might seem intimidating, with lots of steps that mustn’t be skipped.

You might take a look at the oxidation on your fiberglass boat, and your heart sinks.

However, as you work, you’ll soon the boat hull starting to shine. In fact, it can be quite a satisfying kind of work.

If you do your research, buy the proper products, and work hard, your boat will shine as if it’s brand new.

Oh, and don’t forget the elbow grease. You’ll need it.

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