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How to Clean Fiberglass Boat Deck? The Most Detailed Guide

Written by Anthony Roberts / Fact checked by Jonathan Larson

Upkeeping a boat can be laborious and tiring. But, as a boat owner, you have no choice but to practice regular cleaning, particularly because a neat interior promises comfort when you’re onboard.

It’s also essential to take care of the hull as it’s uncovered for everyone to see. Aside from aesthetic appeal, you do it to maintain your boat’s excellent performance.

How to Clean Fiberglass Boat Deck

You can’t deny that keeping your boat clean is crucial. If you’re not know how to clean fiberglass boat deck, this is the right place for you to learn.

Read on to find elaborated details for each of the steps!

Steps to Follow When Cleaning Fiberglass Boat Deck


Things that you need: Boat cleaner, pressure washer, long-handled cleaning device, clean cloth, and a bucket of water

Prepping Up the Deck

Before you do anything else, you need to adequately prep the deck. You can begin with getting rid of debris, and use the following techniques to make the procedure easier!

  • Wiping the Deck

Debris should be removed first before applying the cleaning product so there will be no streaks on the surface after rinsing.

A pair of gloves that are designed for wiping tiny particles or dusting can help you with this job. You may also buy a push broom as it is easy to handle and capable of dealing with a wider scope.

  • Pressure Wash

Another way to carry off debris is doing it by pressure washing. It’s a fast technique that can also make grime and mold disappear. You don’t have to worry as fiberglass can defy the pressure.

The pressure washer that you need to use is not just the regular garden hose. You have to use something like a portable wash-down pump designed for a marine wash.

Applying Safe and Effective Boat Cleaner

The actual cleaning follows the preparation. Your approach should involve safe and effective cleaners that can make the process easy. Here are the ideal choices:

  • Boat Cleaner

Some boat owners go for bleach, a substance that can get rid of mold and mildew. However, it is a hazard to the environment. You can be cautious by finding a safe alternative.

It won’t be difficult to find the right boat cleaner as many options are available in the market. Check if the formula is safe for the environment and the fiberglass as well.

If you’re patient and skilled enough, you can make a DIY cleaning solution for fiberglass. The usual ingredients are baking soda, vinegar, Castille soap, and essential oils.

The cleaner should be capable of loosening mold and grime. It shouldn’t be harsh and damage the deck coating. Some boat cleaners need to be diluted with water.

Diluted solutions are gentle but effective enough to eliminate unwanted spots. It’s also good if you read the label of the cleaning product for instructions to achieve the desired result.

To save the surface from being tarnished, test the chosen cleaner on an inconspicuous area of the deck. It’s effective if it results in a non-slip, shiny surface. A protective coating also comes along with it.

  • Adhesive and Sealant Remover

There can be annoying adhesives that stick on some parts of your hull or deck. A spray remover is a solution for this. It’s way safer than scraping it and you don’t have to worry about leaving your deck with streaks.

A strategy can be formulated after you secure the necessary products. Some would use a long-handled cleaning device to quicken their moves. Think about your safety by starting on the edges and going backward.

Clean your deck with dry footing and watch your every step.

Brushing the Suds

After applying the boat cleaner, the scrubbing is next. It’s a step that ensures the removal of stains and spots. Mildew is sometimes stubborn so brushing needs to be done twice or more as needed.

It can also help if you let the suds stay longer on the deck. Moreover, it’s a must if it has been a while since you last cleaned your boat.

Also, be thorough in cleaning the deck. Don’t neglect small gaps or corners and areas that are hard to reach. Make sure that every inch is cleaned.


You can rinse the deck when you’re already satisfied with the cleaning that you’ve done. Every bit of the cleaning solution must be removed. Otherwise, you will see white spots on the fiberglass surface.

Rinsing can be done by a garden hose or pressure washer. If the deck is very dirty, use a pressure washer then do the previous step and rinse again.

Spot Cleaning

In some instances, there are relentless spots that demand more attention. When you still see them after initial washing, get a damp rag with a small amount of the boat cleaner and focus on eliminating them.

Of course, don’t forget to rinse.

Buffing and Polishing

The most important step in cleaning the fiberglass boat deck is the last one. This part is your chance to protect the surface. You have to buy a protective coating like boat wax to block any stains and spots.

Buff and polish to bolster the deck’s finish and block damaging outdoor elements as well as wear and tear of everyday use. You can look for a kit that has both buffing and polishing solutions for this need.

You can skip this process but go through with it will help you maintain the good condition of your boat. It also makes future cleaning sessions easier.

Other Cleaning Process


Removing Wax from a Fiberglass Boat Deck

The wax that you apply on the fiberglass boat deck is for protection and great appearance. Unfortunately, it discolors after some time. So, removing it is a part of cleaning the deck. Here are some ways on how to do it:

  1. Get a clean cloth to soak in the floor wax stripper or oil compound.
  2. Mix a cup of dishwashing liquid to a gallon of water in a large bucket. Use this ratio to wipe away the wax.
  3. Wipe the oil compound on the cloth over the wax in a circular motion.
  4. Wash the compound using the bucket mixture that you’ve made with a clean cloth.
  5. Wash it away with clean water.

Making Oxidation Disappear

Boat owners find oxidation a nasty presence as it’s difficult to remove. To save you from deep scratches and bad cases of oxidation, wet sand can be used.

A marine-grade polishing compound like riptide or crushing liquid component is helpful most of the time. After the oxidation disappears, the fiberglass and gel coating reveals their brand new look.

Removing Leaf Stains

A waterline stain remover can safely remove stubborn leaf stains. Hence, you don’t have to worry about damages.

You can also check out some other tips and tricks to cleaning your boat from this video.

Frequency of Cleaning Fiberglass Boat Deck

When your boat is on the waters 24/7, it’s recommended to clean it after every use. But, it’s not necessary to use a boat cleaner each time the cleaning is needed.

You can just spray it after use and thorough cleaning can be done once a week. The same frequency is also applicable when you occasionally use your boat. Spraying after use will prevent grime from accumulating on the surface.

Thorough cleaning is needed as your boat is exposed to water and salt most of the time.

Sum Up on How to Clean Fiberglass Boat Deck

Collect the necessary things before you go through the steps on how to clean fiberglass. In this way, you save time and can continue work without disturbance.

Aside from thoroughly cleaning it, you have to be careful not to damage the surface. There are many boat cleaners for fiberglass that are effective but gentle. Again, look closely so you won’t miss any spots.

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