The Best Cleaners for Fiberglass Boat in 2021

Nicholas Swartz
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This is an epic post for anyone who owns a fiberglass boat or is thinking about buying a nice boat. Clean and shine that gel coat!

Fiberglass boat owners know that proper boat care is a must if they want to keep their boats looking good and looking new.

Although fiberglass isn’t a material you might think of when it comes to boat cleaning, there are special cleaners that will keep your boat looking its best for years to come. These cleaners are designed to avoid stripping your boat of UV protectants and they are tough on dirt and grime.

The best boat cleaners for fiberglass are the ones you need to protect your boat and keep it looking new for years to come.

NameCategoryProduct
Collinite Fiberglass Boat CleanerBest OverallCollinite Fiberglass Boat Cleaner
TotalBoat White Knight Fiberglass Stain RemoverBudget PickTotalBoat White Knight Fiberglass Stain Remover
MEGUIAR'S M-4965 MG Fiberglass Oxidation Removal KitUpgrade PickMEGUIAR'S M-4965 MG Fiberglass Oxidation Removal Kit

1. Collinite Fiberglass Boat Cleaner

Our rating: 9 / 10

Collinite Fiberglass Boat Cleaner

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Pros:

  • Removes and prevents oxidation
  • Tough on stains
  • Treats hulls and bottoms of all fiberglass boats
  • Safe on gel coats, paint, and fiberglass
  • Available in convenient pack of 3
  • Exceeds US Coast Guard requirements
  • Available at a great price

This fiberglass cleaner is a heavy duty marine cleaner that is tough on oxidation, tough on stains and tough on fiberglass. It is perfect for fiberglass boats, kayaks, PWC, and other equipment that is made of fiberglass.

The cleaner is able to remove oxidation, stains, and build-up while extending the life of your fiberglass and keeps it looking like new.

The fiberglass cleaner is also very easy to use; you simply spray on the surface and rub into the fiberglass. The cleaner has a solvent that effectively dissolves oxidation, removes soils and grime, and protects against future oxidation and UV rays to extend the life of your fiberglass.

2. MEGUIAR'S M-4965 MG Fiberglass Oxidation Removal Kit

Our rating: 9 / 10

MEGUIAR'S M-4965 MG Fiberglass Oxidation Removal Kit

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Pros:

  • Will dissolve rust
  • 100% acid-free biodegradable formula
  • Safe for use with gel coat and plastics

Meguiar's is a great brand when it comes to detailing products. This kit comes with three applications to remove oxidation on your fiberglass. These applications are measured in ounces, so you'll be able to hold them in your hand.

The one thing that we really enjoy about Meguiars products is the quality. This kit was made specifically for removing oxidation, so it'll do the trick in getting rid of that unwanted build-up.

3. Better Boat Hull Cleaner

Our rating: 8 / 10

Better Boat Hull Cleaner

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Pros:

  • Removes oils, rust, and salt stains from fiberglass and pained boats
  • Won’t fade hull
  • Safe for boaters
  • Non-toxic solution
  • Remove stains quickly
  • Easier to clean with the Better Boat hull cleaner
  • Works great
  • Does not contain ammonia, trisodium phosphate, and phosphates
  • It gets rid of tough stains
  • Works very well

4. Star Brite Instant Hull Cleaner

Our rating: 8 / 10

Star Brite Instant Hull Cleaner

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Pros:

  • Trusted name and solid reputation for high quality products
  • Powerful stain remover
  • Works on both fiberglass and wood
  • Removes sea scum easily and quickly
  • Least expensive option on our list

The Star Brite instant hull cleaner is designed to do one job and one job only: remove stains and scum from the surface of your boat. This is the best boat cleaner if you’re looking to tackle stubborn stains and scum on a budget! It works on either fiberglass or wood, which is great for the versatility. When left on overnight, this boat cleaner is said to remove paint scum from the hull. What’s nice about this product is you can use a small amount for smaller jobs. It’s more economical to use a small amount than to use a lot.

5. Davis Instruments FSR Fiberglass Stain Remover

Our rating: 8 / 10

Davis Instruments FSR Fiberglass Stain Remover

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This 16-ounce bottle of fiberglass stain remover from Davis Instruments is formulated with a special blend of oils and surfactants that are extremely effective at eating through the gelcoat surface on fiberglass boats and removing stains from fiberglass boats.

It is also a great and popular choice for removing MTBE fuel spills that can ruin your boats finish. The label itself is plain and simple and the bottle has a small opening so you can even put your finger over it to control application.

Many of those who review this product are quite amazed with the sheer effectiveness of the stain remover and almost all of them say it has worked better than they thought it would.

6. Meguiar's M6732 Marine/RV One Step Compound

Our rating: 8 / 10

Meguiar's M6732 Marine/RV One Step Compound

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The Meguiar's M6732 is a heavy-duty formula, in fact it’s a two-step formula, but you can use it as a single step compound. It’s compatible with fiberglass, gel coat, aluminum, metals, plexiglass, and even painted surfaces.

It’s made to remove oxidized paint, scratches, and marine growth without harming your boat.

As a single step application, it doesn’t need to be rinsed off, but it would help you with your cleaning and with the performance of the product if you would rinse.

7. Star brite Ultimate Fiberglass Stain Remover

Our rating: 8 / 10

Star brite Ultimate Fiberglass Stain Remover

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Pros:

  • Removes tough stains
  • Works well on fiberglass, gelcoat and hulls
  • Biodegradable and environmentally safe
  • Non-flammable

A fiberglass boat can be cleaned with this fiberglass cleaner in a number of different ways. Cleaning it with a sponge, cloth or chemical sprayer will all get the job done.

The product is effective on all types of fiberglass surfaces and is even effective underwater.

Best of all it does not appear to create damage to the fiberglass finish.

8. TotalBoat White Knight Fiberglass Stain Remover

Our rating: 7 / 10

TotalBoat White Knight Fiberglass Stain Remover

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9. Bio-Kleen Fiberglass Cleaner M00605

Our rating: 7 / 10

Bio-Kleen Fiberglass Cleaner M00605

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The Bio-Kleen Fiberglass Cleaner is an extremely efficient cleaner for fiberglass boats. If your boat has stains, scum lines, and hard to remove algae and other stubborn spots, then this fiberglass cleaner will do the trick.

This cleaner is specially formulated to remove organic residue and mildew stains from the surface of fiberglass pools and boats. It is also an excellent cleaner for fiberglass and acrylic bathtubs, sinks, showers, and patio furniture.

The Bio-Kleen Fiberglass Cleaner is made from a non-acid formula that is safe and biodegradable. If you have a well-kept fiberglass in the pool, you’ll definitely want to get this cleaner for your fiberglass boat.

10. 3M Marine Cleaner and Wax

Our rating: 7 / 10

3M Marine Cleaner and Wax

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Pros:

  • Very effective in removing stains and dirt
  • Easy on-and-off application
  • Protects your boat against UV rays and other elements
  • Reduces the need for frequent polishing and waxing

This 3M Marine Cleaner Wax is a highly-effective cleaner and polishing product for fiberglass and is usually used on boats.

It instantly removes oxidation, grime, and scratches from your boat. The marine cleaner has a 3:1 ratio of cleaners and wax. This is an extra-cheap yet highly effective boat cleaner.

The product comes in a spray bottle with a 16.9 fl oz capacity. It may take some time before it removes all the dirt and grime and some stubborn dirt may require a bit more effort. To polish your boat and have a great-looking shine, all you need to do after it has been cleaned is to apply the marine wax.

Frequently Asked Questions (FAQ)

What is the best thing to clean a fiberglass boat with?

Whichever cleaning product you choose, be sure it is specifically designed for fiberglass and watercrafts. Most household items should be okay. Just be wary there is some debate out there about what is safe.

If you have a lot of time on your hands, you can also build your own boat cleaning system, using common household duct tape and a couple of cloth hoses.

Basically, you take a length of hose, wrap it around the exterior, covering all of the cracks and marks until the entire boat is covered. Then you take a super-sized roll of duct tape and tape up the hose.

Next, you take the other end of the hose and connect it to a pressure washer. The goal here it to blast the mud and other grime off your boat. With any luck, the duct tape will actually help keep the water from going into the cracks and marks, keeping your boat clean for much longer.

How do you remove heavy oxidation from a fiberglass boat?

Perhaps you just inherited a boat from your grandfather and you want to use it but it has some built-up oxidation on the surface of the boat. The natural inclination might be to just get some elbow grease out there and start scrubbing.

One big mistake when it comes to removing this build-up is that sometimes it won’t come off with just elbow grease and soap. If you want to make sure you don’t end up with swirl marks, you’re going to need to take some steps to be more thorough in your cleaning.

Before you go out and spend money on products that you think will get the job done, though, you’re going to want to see if you want this type of solution.

What is the best boat cleaner?

Keep in mind that there are numerous products on the market that claim to be the best boat cleaner. Most boating detergents are suitable with very similar result. Yet, it is also very easy to get tangled up in the various brands, types, and formulas.

Look at the label and make sure that all natural ingredients are used for a safe and effective boat wash. The last thing you need is to attract pests with harsh chemicals.

In the end, only you know what is the best cleaner for fiberglass boat considering your own needs. The above list can be used to serve as a guideline.

Is it OK to pressure wash a fiberglass boat?

Pressure washing your boat is not the best way to clean the hull of a fiberglass boat. Most pressure washers emit water at a temperature significantly hotter than temperature of the water that the hull is submerged in. This causes the gelcoat to expand and contract as it alternately heats and cools. Over time, this can cause cracks and delamination with the gelcoat and/or the fiberglass below.

The right way to clean a boat is to use a pail, soap, scrub brush and rinse the entire hull with a hose equipped with a single nozzle at the appropriate psi.

Conclusion

You will not be able to have a fiberglass boat that is always free from scratches, but even if you can prevent most, that would be a great achievement in itself. Here’s a guide to caring for your boat and keeping it in tip-top shape.

Our Recommendation

NameCategoryProduct
Collinite Fiberglass Boat CleanerBest OverallCollinite Fiberglass Boat Cleaner
TotalBoat White Knight Fiberglass Stain RemoverBudget PickTotalBoat White Knight Fiberglass Stain Remover
MEGUIAR'S M-4965 MG Fiberglass Oxidation Removal KitUpgrade PickMEGUIAR'S M-4965 MG Fiberglass Oxidation Removal Kit