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How To Clean A Fiberglass Boat? 11 Tips To Follow

Owning a boat, especially one made of shiny white fiberglass, is a joy and privilege. But like any prized possession, a boat requires regular care and cleaning to keep it looking its best.

Follow this complete guide to learn the most effective methods for keeping your fiberglass boat clean from bow to stern all season long.

How to Clean a Fiberglass Boat?

To clean a fiberglass boat, follow these simple steps:

1. Start by Gathering Your Supplies

Before tackling any cleaning task, be sure you have all the necessary supplies on hand. To thoroughly clean a fiberglass boat, you’ll need:

  • Mild boat soap or detergent
  • Soft cloths and sponges
  • Bucket
  • Hose with spray nozzle
  • Protective eyewear and gloves
  • Plastic scrapers or putty knives
  • Step stool or ladder

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2. Wash the Hull

how to clean a fiberglass boat - someone with a bucket of water standing next to a boat hull

The hull of your boat takes the most abuse from the elements. For a basic hull cleaning:

  • Mix boat soap with warm water in your bucket. Avoid dish soaps as they can remove protective coatings on the fiberglass finish.
  • Dip your sponge in the sudsy solution and wipe down the hull from top to bottom.
  • Use a hose on a light spray setting to rinse soap residue completely. Check for any remaining dirt and spot clean as needed.
  • Wipe the hull with a dry soft cloth to prevent water spots.

3. Target the Deck

someone cleaning a boat deck floor

The boat deck receives plenty of foot traffic, so needs frequent scrubbing. Grab your soft brush and bucket of sudsy water.

Get up on your hands and knees and scrub the fiberglass deck using broad circular motions. Be sure to get into corners and around the hardware. Rinse thoroughly with your hose.

4. Make Metals Shine

someone cleaning metal parts of a boat

Metal fittings like navigation lights, rails, and ladder rungs will also need attention.

Make a cleaning paste with baking soda and water. Apply the paste to the metal with a damp cloth.

Let it sit for a few minutes before rubbing off and rinsing. For stainless steel, use a metal polish and microfiber cloth to restore a factory shine.

5. Sanitize the Cabin

A clean cabin is essential for an enjoyable day of boating.

Sweep out any loose dirt or sand with a brush and dustpan.

Use a cloth moistened with your sudsy bucket water to wipe down seats, storage compartments, the cabin floor, and any other interior fiberglass surfaces.

6. Restore Glass Surfaces

Glass windshields and mirrors quickly accumulate dirt, salt, and grime.

Clean them inside and out with a specialty boat glass cleaner and lint-free cloths for a crystal clear view. Avoid using paper towels as they can leave behind scratches and streaks.

7. Detail Tiny Spaces

Don’t neglect the nooks and crannies that hide dirt and debris.

Use small nylon detail brushes, cotton swabs, or old toothbrushes to gently clean tight areas like openings for water intake valves, around cleats or bow lights, speaker grills, bait wells, and the undersides of seats.

8. Take Care of Canvas

Vinyl and fabric canvas boat covers and bimini tops need specialized care. Brush off loose dirt before wiping it down with a canvas cleaner and protectant solution.

Use gentle circular motions and allow the fabric to air dry before replacing the covers. Harsh cleaners can degrade waterproof coatings.

9. Take It Slow on Tough Stains

If you come across stubborn stains that resist normal washing, break out the heavy artillery.

Carefully apply a cleaning paste for boats with light scrubbing using a soft cloth or brush. Let the paste sit for 5-10 minutes before rinsing.

For waterline gunk that builds up over time, use a plastic scraper or putty knife at a 45-degree angle to lift debris without damaging the hull.

10. Take Extra Steps After Saltwater Use

The salt in ocean water can quickly corrode parts and eat away at fiberglass if left behind after use.

Make it a habit to do a post-saltwater rinse while the boat is still on the trailer.

Spray the entire boat down with fresh water, focusing on the lower unit areas that are exposed to saltwater while running. Make this the first step before doing any soapy washing.

11. Protect and Shine After Cleaning

Once your boat is squeaky clean, protect that sparkling finish between outings with a coat of boat wax.

Choose a high-quality marine wax designed specifically for fiberglass.

Apply using small circular motions. Buff off once hazy for a brilliant, long-lasting shine.


Caring for your boat doesn’t have to be difficult or time-consuming.

Follow this complete cleaning guide to easily remove dirt and grime so you can enjoy your boat’s beautiful finish for many seasons of smooth sailing ahead.

With some mild soap, elbow grease, and proper tools, that shiny fiberglass will continue sparkling like new.

This article was all about how to clean a fiberglass boat and I hope you have gained value from it.

If you have any questions, leave them in the comment section below.

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