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9 Different Types of Boat Cleaners for Fiberglass Boats

A man cleaning a black and white boat with light green cloth.

Constant exposure to harsh elements leads to damage and wearing, ultimately decreasing your fiberglass boat’s good shape. Solving this issue requires the best cleaner to help restore your boat’s former glory.

However, with the countless cleaners flooding the market, you can choose the wrong product, waste money, or further damage your boat’s hull. Luckily, I’ve compiled this guide to help you choose the right cleaner for your boat.   

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Quick Glance at the Best Types of Boat Cleaners for Fiberglass Boats:

3M Marine Cleaner and Wax

3M Marine Fiberglass Cleaner and Wax, 9011, 1 gal

When looking for a fiberglass cleaner, its ability to remove stains shouldn’t be the only feature to consider. It should protect the gel coat or fiberglass shine from harmful elements such as UV rays. You can’t go wrong with 3M Marine Cleaner and Wax. The product is affordable and perfectly meets all needs.

Its unique liquid formulation is designed to rid stains like light to medium oxidation, exhaust stains, and rust. You only have to apply it once to reclaim your boat’s original color.

You’ll like this product because it combines a compound that restores shine and keeps your boat protected and polished even under the harmful UV rays. Plus, it’s easy to apply because it leaves no streaks and works perfectly on gel coat, fiberglass, to car and RV surfaces.

I consider this product perfect because it keeps the surface sleek and vibrant and adds a layer of protection. It also has a specially engineered combination of waxes to help ease the constant worry about sunlight and weather. This gives you more time to enjoy your boat’s shine and beauty.


  • Leaves no streaks
  • Works on car and RV surfaces
  • Polishes the fiberglass surfaces
  • Offers protection from harmful UV rays
  • Lesser time is spent as it combines polishing and cleaning 


  • Not fit for aluminum surfaces

Star Brite Ez-On Ez-Off Cleaner

STAR BRITE EZ-ON EZ-OFF Hull & Bottom Cleaner - 1 GAL (092800)

The first step to cleaning your boat’s hull is looking for a cleaner that removes the dirt effectively. That’s what Star Brite Ez-On Ez-Off Cleaner offers!   

I like the specialized formula used in this product. It doesn’t contain harsh or strong acids or typical ingredients like other cleaners. Its formula also makes it safe to use and eco-friendly.

Moreover, it deals with the hard-marine deposits in boat bottoms and stains on your boat’s hull. Using the powerful and specialized formula ensures all these stains and deposits loosen up, making it quick, easier, and convenient to remove and clean.

Using this hull cleaner is easy. You only have to apply it to the targeted part and wipe gently. You’ll be surprised by how fast it removes the stains.

Star Brite Ez-On Ez-Off Cleaner also saves you time cleaning your boat’s bottom and hull. Whether it’s the marine deposits, waterlines, stains, etc., this boat cleaner can take care of everything. Its powerful and specialized formula can clean and make your boat look brand new in the quickest possible time. Unfortunately, I wouldn’t say I like its odor.


  • Saves time
  • Eco-friendly
  • Safe to use
  • Fast-acting formula
  • Effectively loosens marine deposits and stains


  • Produces a strong odor

MaryKate MK2032 On Off Cleaner

Cleaning a fiberglass boat is often daunting, so you need the best cleaner to do the task perfectly. This is where the MaryKate MK2032 On off Cleaner comes in. I’m impressed with this brand’s effectiveness in removing dirt and stains on the bottom of the boat. Besides removing the stains, it can also remove dirt on the boat’s fiberglass hull.

This product is formulated to protect different types of surfaces from the detrimental effects of the marine environment. Moreover, it doesn’t leave greasy residues on the surface. Instead, it makes the surface brighten, shine, and look brand new and rejuvenated.

I also like that this cleaner can be used easily to perfectly clean the boat’s fiberglass gel coating. You only have to use a paintbrush, apply the cleaner to the targeted parts, and watch all dirt and organic matter instantly disappear.

The only issue noted is that it produces a strong odor. It’s so strong that you need goggles and gloves during use to protect yourself from the adverse effects of the chemicals.


  • Leaves no greasy residue
  • Makes the surface look rejuvenated and brand new
  • Versatile in cleaning surfaces


  • Need to wear goggles and gloves during the application

Meguiar’s M6132 Flagship Cleaner

Meguiar’s M6132 Flagship Premium Cleaner/Wax, 32 Fluid Ounces

Another amazing boat cleaner for fiberglass boats that can remove any tough stains and dirt is Meguira’s M6132. Its ability to easily restore, protect, and clean your boat makes it a must-have in your boat cleaning arsenal. It can also protect your boat from the harmful effects of UV rays.

This product can clean water spots, stains, oxidations, etc. It restores the glossiness of the surface and protects it from the harmful effects of sunlight.

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Meguira’s M6132 is versatile as it can be used on different surfaces like gel coats and fiberglass.  

Moreover, this brand is considered a dual-action polisher as it protects and cleans the surfaces at the same time.

It’s made and formulated with biodegradable and safe ingredients that make it eco-friendly. The only problem I’ve with this product is the quality of the container. At times, you’ve to squeeze the container for the solution to pop out.


  • Dual-action effect
  • Removes different types of stains 
  • Versatility – can be applied to different parts
  • Formulated with safe and biodegradable chemicals


·         Poor quality container

Collinite 920 Fiberglass Boat Cleaner

Collinite No. 920 Fiberglass Marine Cleaner, 16 Fl Oz - 1 Pack

Opt for a cleaner specifically designed to protect the fiberglass hulls from the effects of constant exposure to the marine environment. A brand that will clean and make your boat look brand new. That’s what this fiberglass boat cleaner from Collinite does.   

This product is formulated to shine, clean, and protect surfaces, particularly in the fiberglass hulls of the boat. Several boat cleaners claim to have this triple effect outcome after the cleaning process – but it turns out to be a deceptive marketing strategy.

However, this is not the case with Collinite 920 fiberglass boat cleaner. While testing it, I didn’t expect other results apart from dirt removal. But I was amazed at how this fiberglass boat cleaning agent also makes the fiberglass surfaces appear fresh and look brand new!

I also like this product’s ability to protect any surface it cleans. This includes protection from fading, cracking, or drying, which are the harmful impacts of the UV rays.

Moreover, this product prepares the surface for other purposes like wax application. This type of application adds to the cleanliness of the surface because it gives additional protection and glossiness to the surface.

The only problem with this brand is that it might irritate your eyes and skin with accidental contact. You must protect yourself during the cleaning process by following the stated instructions.


  • Protect the surface
  • Prepare the surface for other applications
  • Shine, protect, and clean fiberglass surfaces
  • It leaves the surface with a natural, brand-new look


  • It might irritate the skin and eyes if in contact

Biokleen BIO-KLEEN M0065 Fiberglass Cleaner

Bio-Kleen M00109 Aluma Kleen - 1 Gallon

Looking for a fiberglass boat cleaner that’s both eco-friendly and effective at removing tough stains can be challenging. Thankfully, Biokleen’s BIO-KLEEN M0065 Fiberglass Cleaner is eco-friendly and keeps your boat stain-free.

Its formula is free from chemicals like aerosol and harmful ingredients that might pollute marine life when exposed to it.

I also like how versatile it is — I can use it to clean any surface. The non-abrasive but highly clinging cleaner keeps my boat’s gel coat undamaged.

It’s the perfect choice for removing and cleaning waterline rust and stains leaving behind a shiny, clean hull, which improves your boat’s appearance.


  • Easy to apply and use
  • Eco-friendly formulation
  • Cleans multiple types of surfaces
  • Produces impressive cleaning results


  • It might be challenging to use in removing dark stains

TotalBoat White Knight Fiberglass Stain Remover

TotalBoat White Knight Fiberglass Stain Remover (15 Ounce)

TotalBoat White Knight Fiberglass Stain Remover can remove scum, rust, waterline stains, and dirt from your boat’s gel coat and fiberglass.

This product comes with a non-abrasive gel formula, which makes it safer to use on your boat. You no longer have to worry about damaging your boat’s gel coat.

I like this product because it can be used on multiple surfaces, besides fiberglass, like stainless steel, painted surfaces, and gel coats. In addition to marine use, you can use it at home, too.

The TotalBoat White Knight Fiberglass Stain Remover isn’t as quick-acting as others but has a fairly fast acting time, about 15 minutes.

Plus, it doesn’t require any scrubbing, so you can sit back and wait for it to work on stains and dirt on your boat’s fiberglass.


  • Easy to use and apply
  • Doesn’t require scrubbing
  • It can be used on multiple surfaces
  • Non-abrasive formulation for safe use on fiberglass


  • Can be challenging to use in removing tougher stains

Davis FSR Fiberglass Stain Remover

Davis Instruments - 790 FSR Fiberglass Stain Remover (16-Ounce)

The Davis FSR Fiberglass Stain Remover can perfectly remove exhaust, oils, rust, and waterline stains. It’s also the best choice for removing road dirt from your boat trailer.

What I like about this product is its non-abrasive stain-absorbing formula. So, it’s safe for use on fiberglass, white painted surfaces, and gel coats.

Its quick-acting nature makes it convenient and easier to remove stains chemically. You only need to spread over on the target surface, then wait for the stain to disappear.


  • Easy to use 
  • Quick-acting nature 
  • Doesn’t leave streaks


  •  It doesn’t remove stubborn stains effectively 

Meguiar’s M6732 Marine RV One Step Compound

Meguiar's M6732 Marine/RV One Step Compound, 32 oz

The Meguiar’s M6732 is the best product for cleaning tough water spots, irremovable heavy oxidation, and scratches. It quickly erases moderate to heavy oxidation, restoring the color and leaving a rich luster on the treated surfaces. Meguiar’s M6732 is specifically designed to clean gel coat and fiberglass.

I prefer this brand because I can apply it by hand or machine. Either way, it offers favorable results and gives a fiberglass boat’s hull a brand-new look.


  • Restores the vibrant color and shine of the surface
  • Removes water spots, scratches, and irremovable oxidation
  • Gentle on the boat and marine life since it’s a biodegradable detergent


  • It doesn’t remove stubborn stains effectively 

Factors To Consider When Buying a Cleaner for Fiberglass Boat

Woman in red shirt cleaing the red boat with sponge.

Countless cleaners are flooding the market, so selecting the best might be challenging. It would help to have a checklist of factors to consider before buying one. After all, you want an effective cleaner that doesn’t damage your boat’s exterior.

Here are factors to check to make an easy purchasing decision.


The pricing of a product doesn’t guarantee its effectiveness. There are expensive boat cleaners that might not achieve your desired expectation. Plus, there are also cheap ones that can meet your cleaning needs. Depending on your budget, you can go for what you consider affordable.


You’d want a product that removes all the unsightly and pesky stains without damaging your boat’s fiberglass surface.

Choose a non-abrasive cleaner that removes stains left behind while still gentle enough not to damage your boat gel coat and fiberglass. Additionally, choose an eco-friendly, biodegradable fiberglass cleaner to avoid polluting the marine environment.

Cleaning Power

This is essential, especially if you want to remove stubborn stains from your boat’s fiberglass.

You’d want to choose a product that’s effective at cleaning your boat without stripping the delicate gel coat.

However, you don’t need strong formulas to remove stubborn stains. Sometimes, you just need another application. So, knowing the cleaning you’re going for will help you decide which cleaner to get. Checking the customers’ reviews can help you make an informed choice in this case.

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Choose a cleaner that cleans your boat’s fiberglass and other surfaces. Invest in a cleaner that can be used for boat and home cleaning.   


As a boater, it’s your responsibility to protect the marine environment. Please, keep the water unpolluted by using products that have eco-friendly ingredients. Avoid using cleaning agents that harm the marine environment.

I’m your basic tree-hugger, but the neighbors took me and my brother out on their boats for a treat when we were children. I’ve never been on a cruise or toured a Navy museum ship, but I did learn to paddle a canoe when I was a Girl Scout. That’s the closest I ever came to boats, and although I can’t tell you funny stories about me and boats, I can explain what gets on boats that makes owners scrub them into oblivion.

What Could Possibly Get On A Boat That Would Make Owners Put It Up On Blocks To Annihilate It?

Water isn’t just water. In lakes, rivers, and oceans, organisms from the tiniest of bacteria to worms to barnacles need a surface to which to attach. From there, the organisms begin a family and cruise the world (or at least the river.)  Worms eat boat material, although this was more common in the days of wooden ships back in the early days of the American colonies. 

The snag to this is that all the organisms attached to the bottom of a boat (your fiberglass beauty or a Navy ship) create a drag that slows down the boat. Add to this the fact that shipworm chows down on the wood of piers, warehouses too close to water, as well as wooden markers of shipwrecks in the oceans.

These aquatic power drills bore holes in any marine wood, which further slows down the boat.

Barnacles are actual living critters in the lobster, crab, and shrimp family. They use legs they don’t need for movement to capture marine food and guide it to the mouth inside the protective shell. Barnacles stick not only to boats and ships but to aquatic animals as well, such as manatees, whales, and sea turtles.

All of this is called biofouling. Organisms emit a blood-like substance they use to adhere to a surface. They endlessly reproduce, making a boat’s hull a slippery, slimy thing. It’s this slime that boat owners put their boats up on blocks to remove. 

Do These Destructive Organisms Befoul Fiberglass Boats?

Yes. While shipworms or Teredos don’t care for fiberglass, other marine organisms can and do befoul fiberglass boats left in salt water. Merchant and Navy ships have used everything from lead to copper plating to anti-fouling paints. Even fiberglass boat owners use the same anti-fouling paints. What do boat owners use to clean their craft?

What Are The Types Of Fiberglass Boat Cleaners?

There are only two types of fiberglass boat cleaners: liquid and gel. Which you use depends on your personal preference. Boat owners prefer gel cleaners due to its ease of application.

Other boat owners wouldn’t think of using anything but liquid cleaners, even if they tend to be a bit messier and require buckets and soft-bristled long-handled brooms. Both do an excellent job of cleaning fiberglass boats.

Wait, Boats Get Rusty? In A Manner Of Speaking, Yes, So You’ll Need Oxidation Remover And Cleaner

Oxidation is when the elements take the shiny surface off an object. You see iron oxide on rusty cars and sliced apples gone brown. It has to be scrubbed off the fiberglass boat. If you don’t, the grit and gunk will still be on the boat, harming it, underneath the wax layer.

So, first, the oxidation has to be scrubbed off with an oxidation cleaner and remover. Then the boat must be sealed. When the sealant is dry, buff the boat, then wax it.

No, Your Boat Isn’t The Kitchen Counter, But You’ll Still Want To Use Fiberglass Stain Remover

Boats aren’t all that’s made of fiberglass, so cleaning stains off fiberglass bathtubs, some cars and RVs, swimming pools, and roofs require the right cleaner. Two types of stains trouble fiberglass items: organic and mineral. Hard water stains, lime spots, salt, and a host of other things leave their signatures on fiberglass boats, so you need a stain remover.

While some stains can be removed by power washing them with water and soap or white vinegar, other stains are more stubborn and require calling in the big guns like this.

But We Were Just Boating On The Lake. How Are There Grease And Oil On My Boat?

Things spring leaks. If it’s a machine, it’s an oily, greasy, slimy mess. Get that boat up on blocks, because you’re going to need to remove the oily, greasy slime before it eats its way beneath the gel coat. Even the best soap, like Dawn that’s supposed to delete grease, won’t cut through some oil and grease.

Only the pros can handle it. Use it to clean the engine as well. 

Did You Know You Can Remove The Red Or Yellow Crud On The Boat’s Bottom, Even After Years Of Growth?

Many boat owners leave their craft in the water for storage, and some almost never take them out of the water. Have you ever been in the water and stepped on slippery stones? The matter that makes the stones slippery is algae. Over time, it calcifies, which turns the matter red.

On boats, it comes out looking either reddish or yellow. The calcified algae just keeps layering itself onto boats until owners take the boats out of the water to clean them.

Only acid will cut through the crud on the bottom of a fiberglass boat. In this particular product, it’s oxalic acid that leaves your boat as if it were new (so sayeth the reviews.) The product is said to be mild enough to clean the crud without harming the fiberglass and is good preparation for polishing the boat.

I Thought You Cleaned The Scales Off Fish You’ve Caught. What The Heck Is Descaling My Boat And Where Did The Scales Come From?

Water travels around the Earth, through stones, along flat and mountainous terrain, and along or around every conceivable type of ground. The water picks up minerals, usually calcium and magnesium, as it flows.

When the water is heated, such as in sunlight or in a home’s water heater, it leaves behind the mineral deposits it picked up along its path to your boat or your water heater. What’s left behind is called scale.

This attaches to a fiberglass hull, unsightly and discoloring. Anything you can use to remove the scale harms the fish and any wildlife drinking the water. Not only that but cleaning it is time-consuming. Not to worry: this cleaner is federally approved as “Biopreferred” and will clean without harming a thing. 

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It Seems You Can’t Get Away From Mold And Mildew. How Do They Get Into Or Onto Fiberglass Boats?

If it’s humid, mold and mildew will grow. If it’s wet and humid, mold and mildew love it. Little to no airflow helps, too. So does dirt and grime. So, if your fiberglass boat is stored in or around water in humid conditions with little to no airflow, guess what?

To prevent mold and mildew, keep your boat exquisitely clean. Store it in a cool, dry place with plenty of ventilation. On the other hand, if your fiberglass boat has already succumbed to mold and mildew, you’ll have to clean it before they damage the boat.

You can use this product on both the carpets and fabrics inside the boat as well as on the hull. It’s safe to use on household fiberglass items as well. Just spray it on, let it sit for a bit, and wipe off. The reviews of this product make it sound miraculous, so give it a go.

There’s A Pink Stain On The Bottom Of My Fiberglass Boat. What Is It And What Will Remove It?

At the beginning of this piece, we discussed the bacteria that attach to boats. Bacteria interact with whatever it’s attached to, so it turns different colors. That explains the pink hue; some are brown, red, orange, and so on. Bacteria is as old as the Earth and is found everywhere.

It’s just a little difficult to clean off boats. However, this product cuts through the slimy mess without throwing out your back scrubbing it off. It does, however, contain acids, so don’t use it near water. Clean your boat in a well-ventilated place or you could become a bit ill. 

I’m Guessing The Interesting-Looking Growths On My Fiberglass Boat Are Barnacles. How Do I Get Rid Of Them?

Barnacles are actually living organisms belonging to the lobster-crab-shrimp family, or crustaceans. They attach to marine life, including marine animals, and do their growing and feeding there. Some boat owners scrape them off their boats while others use spray cleaners for an easier-on-the-back experience. This product, for instance, is one of the latter.

Don’t be fooled by the name of the product. BioKleen contains acids, so wear gloves and don’t inhale it. I, personally, wouldn’t use it around water. To give you an idea of how well it works, one of the reviewers said she cleaned her boat on her concrete driveway.

When she was finished, the spot on the concrete was nice and white. It goes without saying her boat was exquisitely clean.

What Are The Benefits Of Using Fiberglass Boat Cleaners? What Are The Disadvantages?

Fiberglass is used in many applications, one of which is boat hulls. It’s finished with a gel coat that gives the craft its shine. The elements and marine encrustations, though, can eat through the gel coat, leaving the boat dull and damaged. Boat owners use special fiberglass boat cleaners to cut through the crud so they can restore their boats to their former glory:

    • Boat owners need to read the products carefully to see what kind of crud the product eliminates. The products cut through their particular crud like a hot knife through butter.

    • Boat cleaners save the owner time. He won’t have to use elbow grease.

    • Many boat cleaning products combine the crud cleaner, a polish, or wax for a complete job in one bottle.

    • Boat cleaning products are great protection for fiberglass boats.

    • Boat owners can spend more time enjoying their craft.

There are some disadvantages to using boat cleaners:

    • Some of the chemicals and acids used in these products are harmful to marine life and sometimes humans (inhaling them or getting it on the skin.)

    • The harsh chemicals and acids could leave scratches on the boat or otherwise damage it.

There’s A Long And Distinguished History Of Boat And Ship Cleaning

Ancient mariners sailed in boats made of hides or bundles of reeds tied into planks. It wasn’t long before the Egyptians turned to oak for the planks of their merchant and warships. They soon found the problems associated with wooden ships, developing treatments of tar, oils, tallow, and wax mixed with the hair of animals as coatings for the wood.

Sometimes, boat builders would build onto the vessel a layer of wood the worms could eat which protected the actual wood of the ship.

It wasn’t until relatively modern times that shipbuilders nailed sheets of copper to the bottom of ships. Copper is deadly to marine crud. Lead sheeting didn’t work, as it interfered with the iron fittings holding the planks together. Copper was expensive, but it worked, so merchants and the navy went with it.

Today’s method of applying anti-fouling paint to ship and boat bottoms is cheaper and just as effective as copper plating. For one thing, the anti-fouling paint contains elements deadly to marine crud such as copper, mercury, and arsenic.

The turpentine and alcohol used in the paint evaporate upon application, and a binder is used to ensure the durability and flexibility of the application. Even fiberglass boats are painted with this anti-fouling paint.

Want To Hear A Few Tips For Cleaning Your Fiberglass Boat?

1. Protect yourself. You’re dealing with harsh chemicals and acids, and you don’t want to inhale those or get them on your skin. Wear goggles along with a face mask like the masks they use in asbestos removal. Wear thick protective gloves, long sleeves, and shoes with toes instead of flip-flops.

2. Brushes. You don’t want to use a stiff-bristled brush to wash your boat, because the stiff bristles could scratch the gel coat. Use a soft-bristled brush, or even better, a microfiber or wool paint roller on an extended handle.

3. It takes time. Establish a day and time when you have nothing else to do in order to make your fiberglass boat shine. Cutting corners and/or skipping steps means (a) your fiberglass boat isn’t properly protected, and (b) you’ll have to go through it all again. The better you protect your boat’s gel coat, the longer you can enjoy your boat before you have to rinse and repeat.

4. Ventilation. Make very sure you clean and protect your boat in a well-ventilated area to avoid inhaling the chemicals and acids.

5. Cloths. Use microfiber cloths to dry your boat after each step in the cleaning process.   Each step requires a perfectly dry boat. Cotton or wool cloths don’t absorb as much moisture as microfiber, thus leaving moisture behind. Make very sure the boat is completely dry before beginning the next step in the cleaning process.