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How to Clean Fiberglass Boat Deck? – Step by Step Guide

Fact checked by William Hart

how to clean fiberglass boat deck

Owning a boat can be fascinating and exciting. But sometimes it is exhausting because of the insurance, fees, and maintenance of decks and engines. Cleaning the deck is already a long process, let alone maintaining and preserving the boat. No worries though. You’re in the right place for the solution.

In this article, we will provide a detailed step-by-step guide on how to clean fiberglass boat deck. We can’t promise a quick and simple process. However, you have our word that the procedure is straightforward to follow. Plus, your deck is about to be shiny, spotless, and ready for your next adventure.

Briefly, you will prepare the deck for cleaning by removing any obstacles and brushing the floor off, then pressure washes it, apply soap and wait. After that, scrub the dirt off the surface and give the deck one final rinse. Lastly, dry it with a soft cloth. If there are stains left, use a fiberglass stain remover. An optional step is to apply a wax layer for further protection. Dive in for more details!

Table of Contents

What You Will Need


A long deck brush

A good long deck brush should feature durable bristles and blocks. The long handle allows you to reach high areas and quicken the cleaning process. Deck brushes come in many sizes, shapes, and bristle types. For cleaning a painted boat deck, avoid stiff bristles.

In case you’re wondering whether a wire brush can get the job done. Sadly, the short answer is no. A wire brush will damage the fiberglass, leaving rough spots on the surfaces.

Clean rug or cloth

Prepare a few large pieces of clean rug or cloth to dry the boat deck after cleaning. Old cotton T-shirts will be fine as long as they are clean.

A pressure washer

A pressure washer is a necessary household tool. Whether for the driveways, your vehicles, or your decks, it is going to take your cleaning game to the next level. However, if you own a painted non-skid deck, we recommend skipping this as the high water pressure can damage the paint.

Water bucket

Of course, how can we forget a water bucket? If you’re far from a clean water supply when cleaning, which is the case for most boat owners, prepare a bucket of water.

Boat soap or deck cleaner

Soaps or cleaners specifically made for boats are crucial when it comes to cleaning a non-skid boat deck. Never use other cleaning detergents as their pH level can damage the fiberglass surface. Both products marked as boat soap or fiberglass boat deck cleaner will work well in this situation.

In case such products are not available, you can actually make a DIY boat deck cleaner by mixing dish detergent with warm water. Make sure the dish soap you use is ammonia-free.

A fiberglass stain remover

Fiberglass is one of the materials that stains tend to cling on tightly, especially those shiny white decks. If your boat has coffee, wine stains, or stains from grime, prepare a fiberglass stain remover. However, never use acid-based stain remover on painted, galvanized, or varnished surfaces, as it will discolor the areas.

Boat wax

Waxing is essential to maintain the color and shine of your boat. Also, it makes regular cleaning easier by preventing grime, stains, and dirt from clinging tightly to the surface. Therefore, don’t skip this step.

Choose waxes that are durable and can stand up to saltwater, the sun, and algae. Some popular boat waxes are Meguiar’s Flagship Premium Marine Wax, Collinite Paste Fleetwax No. 885, and Scotchgard Marine Protective Liquid Wax.

While you’re on this, if you own a boat buffer and polisher, get them ready. Otherwise, you should prepare a soft cloth or polishing pad. Puffing by hand is fine but it might take a lot of time.

Safety gear if needed

Last but not least, protect yourself when working with bleaching, detergents, waxes, ect by wearing goggles, rubber gloves, or safety clothing if necessary.

Steps to Clean Fiberglass Boat Deck

Now that you’ve gathered all you need. Let’s give the boat deck a good wash!


Step 1: Prepare the deck for cleaning

Prepare the deck for cleaning by picking up stuff on the floor, and removing obstacles like chairs and appliances. Then, brush off any dirt on the surface.

Step 2: Pressure wash the deck


Don’t use soap or cleaner yet. In this step, run your pressure washer all over the deck. This will remove mold, dust, and help quicken the cleaning process. Again, if your deck is painted, pressure washing can harm the paint. Instead, use a water bucket to water down your deck.

Step 3: Apply deck cleaner or boat soap


Make sure the whole fiberglass surface is wet before applying deck cleaner or boat soap. Spray, or put a decent amount of soap onto the wet surface. Then, move it around to distribute an equal amount all over. For optimal cleaning, take your time to ensure no spot is left without soap.

Deck cleaners and boat soaps are specifically designed for the marine environment. If it concerns you, know that our swimming friends are totally safe.

Step 4: Let it sit for two to three minutes

Don’t rush in and brush the soap off. Let it sit for about two to three minutes, but no longer than that because dried soap can be difficult to work with. In this step, the cleaner will soften the grime, dirt, and even absorb light stains. Take a break, and drink some water as we will need some strength in the next step.

Step 5: Brush the deck

Go ahead and grab the long deck brush. Use it to clean your deck thoroughly. But don’t scrub so hard that the surface is scratched. Do one small area at a time and rinse it off with water immediately. Don’t forget the hard-to-reach areas.

Step 6: Wash off the deck


Give the deck a final rinse by running water down the whole surface. You can use a pressure washer in its low setting or a water bucket. This step ensures no soap or water spot is left on the fiberglass deck.

Step 7: Dry

Never let your deck dry naturally because water can leave a thin film on fiberglass. Instead, dry the surface with a soft clean cloth or rug right after washing the deck off. This gets rid of any water residue and leaves you with a spotless fiberglass deck.

By now, if your deck comes up clean and you are happy with the result, skip step number eight. Otherwise, grab your fiberglass stain remover.

Step 8: Remove stains

Remember to wear rubber gloves, goggles, or any type of protective gear as needed when working with a stain remover. Put a small amount of the detergent onto the stained areas. Let it sit for about five minutes or even longer if necessary. Then, remove the detergent with a soft cloth.

Before applying the stain remover, know that it can cause discoloration and bleaching to the paint layer on your deck if there is.

Step 9: Apply a thin layer of polymer wax

This step is optional but highly recommended. A thin layer of polymer wax can help protect your non-skid fiberglass deck from oxidizing and preserve its good condition in the long term. However, if your deck is old and worn, avoid wax as it can make your deck slippery.

To apply wax to the surface, use circular motions. You can apply the wax by hand or use a boat buffer and polisher. Remember to follow the specific instructions on your wax.

Step 10: Build a habit

We suggest using water to rinse your boat deck after each outing on saltwater. It is to prevent oxidation, mold, and algae. Don’t use soap or cleaner as these can wash off the wax job that you’ve done.

Cleaning your non-skid boat deck thoroughly with soaps and stain removers should take place once every three to six months. It depends on the frequency of your boat use. Nonetheless, try to build a habit of cleaning your boat periodically to ensure a non-skid deck and maximize its lifespan.


Don’t take it lightly when cleaning a fiberglass boat deck. The wrong steps can cost you dearly by damaging your expensive fiberglass surface. Learn about the cleaning and preserving procedures carefully to maintain your boat’s best condition.

It is our pleasure to have your attention. If you follow this guide on how to clean fiberglass boat deck, please share your result. It will be exciting! Feel free to leave a comment should you have any further questions. We are more than glad to help. See you then!

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